bridge deck catamaran

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Catamaran Structure – Bridge Decks and Cross Beams

• Post author By BJ Porter
• Post date April 30, 2021
• 7 Comments on Catamaran Structure – Bridge Decks and Cross Beams

Editor’s Note: Many thanks to Ted Clements of Antares Catamarans and Shane Grover of Seawind Catamarans for patiently answering our questions.

There are a lot of reasons why catamarans are more expensive than monohulls. It’s not just the two hulls. There are many more complicated calculations and structures needed to build the complex shapes.

Building a bridge deck and the structures around a pair of hulls is a lot more difficult to design and build than a single hull, and we’ll explore a little about why.

Part 1: Forces on the Hulls

Load and force calculations on a boat hull isn’t a simple calculation, and even monohulls take a lot of designing to build a shape which performs well and has the strength to hold together at sea. Land vehicles have fairly predictable forces and motion on them, but boats can take forces and stresses in any direction.

Waves slam from all directions, boats plunge off waves and get smacked around in chop. Wind forces stress masts and rigging, which applies bending moments and forces to chain plates and the hull. Hulls flex and bend with this motion, and even from tensions applied to the rig.

Elements of drag, hull shape, keel shape and rig design all factor in, whether it’s a heavy, stiff cruising boat or a light, high performance racing machine. Those forces have to be figured, and materials and constructions are made to suit the conditions and situations where the boat will sail.

And that’s just a single hull. When you add a second hull to mix, you add in a whole new set of loads.

Bananas and Pencils

To illustrate these additional loads, we’ll do a thought experiment with a couple of household items. You can try it for real if you want to – but you’ll need two bananas and a few pencils.

Start with the bananas laying parallel to each other, then run a single pencil through the midpoint of each banana (the hulls) to connect them. They’re connected, but when you pick it up, what happens? They don’t stay parallel, of course. We need a second pencil or even a third one, to keep them in place.

The pencils are the crossbeams you’ll hear about in catamaran construction. If you put two of them through the bananas to connect them about 1/3 of the way from the end of each banana, you’ll get a fairly stable platform (for something made from soft fruit and pencils).

Imagine picking up this banamaran with two crossbeams with one hull in each hand. How can we still move the hulls?

First, we can twist one half back and one hand forward, putting lots of force on the crossbeams. To stop this, we could use much stronger beams, and we could put more beams at the ends of the bananas.

If you rotate your hands and the bananas, you demonstrate another type of force on the crossbeams. Pushing the bows or stern together also can move the hulls.

Building the Boat

Now imagine putting weight on the pencils – you’re adding the bridge deck. The mast sits on the bridge deck and creates additional loads and stresses on the crossbeams and hulls.

Finally, we add a sailing rig on top of the weight on the pencils. The rig needs support to stay up. On a monohull, stays run to the bow and stern to support the rig. But a catamaran the mast is centered between the hulls. The tension on the rig will provide upward pull on the hull shapes and usually attach to bow crossbeams. So we’re now pushing down on the middle of the bananas while pulling up on the tips.

The challenge to the catamaran builders and designers is to account for all these forces and build a pair of hulls capable of absorbing these loads without breaking or separating the hulls.

Part 2: Crossbeam Design

Catamarans are not new concepts; double hulled sailing canoes were used in Polynesia and Melanesia long before European explorers arrived. One of the first recreational catamarans was designed and built in 1876 by Nathanael Herreshoff and sailed well enough that the New York Yacht Club banned multihulls from racing.

Most beams are hollow to save weight in increase strength for the amount of material used. A hollow cylinder or rectangular tube gives more resistance to bending per pound of material than a solid rod of the same weight. There are mathematical explanations beyond both the scope of this article (and my ability to explain), but it’s important to know where the loads on beams are supported to understand this.

Greatly simplified – bending a beam creates compressive loads. The further from the center of the beam, the higher the resistance to compression. A rod will have a narrow diameter and resistance is lower. But if you make a cylinder or square tube from the same amount of metal (or fiberglass) you will have the same cross-sectional area, but the compressive force is applied further from the center of the cylinder.

Think of an I-beam from building construction. The compression is on the sides of the I-Beam, but the part in the middle is mostly to keep the sides in place, not bear the load on the beam in high stress applications.

Original Beams

A close look at these boats shows clear and obvious crossbeams connecting the hulls. Duplex , the early Herreshoff boat, had three clear crossbeams and a cockpit on the aft two between the hulls.

Smaller beach and racing cats will have obvious crossbeams, since the decking is usually a stretched piece of canvas or webbing. Other open bridgedeck catamarans, including many home builds, may have actual beams across them holding the hulls in place. And most cats will have some sort of beam across the bows as well.

But when you look at modern bridgedeck catamarans, you notice something strange about the beams. There aren’t any actual “beams” built into the boats.

Modern Cruising Cats – There Are No Beams

It’s more you notice something missing about the beams. Modern bridgedeck catamarans don’t generally have actual crossbeams built into them, as if you were glassing a beam or post into the boat. Instead, the construction of the boat is built around a design the provides the mathematical equivalent of a “beam.”

Bear with me. It took a while for me to get my head around this, too.

Picture a box – even a simple shoebox has rigidity to its sides. Yes, you can crush it, but the hollow sided box offers a lot more stiffness than a piece of cardboard on its own. The structure of the beams is in essence a box built between the hulls, with super strong modern laminate materials providing stiffness to take the loads and stresses.

When modern cats are designed, the “crossbeam” is a combination of internal structures built and connected to the bulkheads that create the load bearing capabilities of a hollow beam section. So the “beam” exists mathematically in the designer’s wireframe drawing of the boat, but when it is built, it is not an external beam added to the structure, but rather a set of structures that act like a beam because of their physical design.

Developments in materials technology over the last few decades allows for shapes and strengths that couldn’t be built with traditional materials like wood or metal.

Part 3: Building a Bridgedeck

Building the bridgedeck is the key piece of fiberglass catamaran strength. To be able to build a boat which can handle all these twisting and torsion forces, creating that “box” to add the strength, catamaran builders take one of several approaches. All can be effective and meet the design requirements, but there may be other reasons a builder chooses a particular approach.

“Tooling” refers to all the molds needed to shape a fiberglass hull. Tooling can be made from a number of different materials and represents a significant investment for any new production catamaran. Costs can run to many millions for tooling durable enough to build a hundred or more boats without changing design and build tolerances.

Molding and tooling to build hulls is a major expense, no matter which approach a builder takes. Building tools and molds can run into millions of dollars in expenses for materials and labor, and molds built for production runs of boats are considerably more expensive than tooling for a one-off or unique design. All of these factors into the decision making behind a build process.

Building a multihull also presents unique challenges compared to building monohulls. Building a single hull can be a fairly linear process – the hull is laid on the mold and built, the inside is fitted out, and decks are attached. While that’s a simplification of the process, it is relatively straight-forward because there is only one hull.

For catamarans, the integral bridgedeck structure doesn’t lend itself to a step-wise assembly. The crossbeams and bridgedeck need to be built integrally before the interior and decks are completely finished. For the builder, this means some parts of the boat have to be finished with reduced access to interior sections of the boat. For the designer, the challenge to is to make the boat so the builder can build it efficiently. For production vessels with build runs in the hundreds, cost effectiveness and production efficiency is crucial.

Not only does the bridgedeck hold two hulls together against all the twisting and torsion forces we’ve discussed, it also has to carry cargo. It holds the living space in the main saloon, as well as passengers and equipment.

Think back on the shoebox – it has compressive strength from the ends, but any individual side is fairly weak. You can deflect the sides easily. While this is fine on a shoebox, it would be disconcerting if the deck flexed and bounced when you walked across it. The bridgedeck also needs strength from the top and bottom to take this load in the central parts of the boat, away from the “box.” You can’t just make the decks and floors massive, that sacrifices headroom and internal volume. Instead, internal structures and stiff construction materials have to take up the load.

Two Piece Molding

Some builders build two hulls individually. One mold can be used if the hulls are identical, and the hulls joined later in the build process. Like any design and build decision, there are pros and cons for the builder which can affect the cost of the final product. If built correctly, there are no compromises in strength from a one piece mold.

For the builder, a one piece mold is much easier to handle. Any hull built on a mold will have to be removed from the mold once the hull is laid, and a single mold is smaller, lighter, and narrower. Breaking a hull out of a mold is a complex process, and may involve cranes and heavy equipment to support the hull as it comes of the mold and to protect the tooling from damage. To remove a hull, you need space to lift the mold and to get heavy equipment around the tooling. And you’ve got to put the molds some place when it’s done.

Connecting two hulls precisely once they’re molded is a more complex task. Unidirectional fibers bond key structures to bulkheads to build the support “box” making up the crossbeams. Although a one piece mold will give an inherently stronger single-material connection between the hulls, more than sufficient strength can be built in with advanced fiber and resin choices (such as carbon fiber and epoxy) when then build the deck connection.

One Piece Molding

Most production catamaran builders have moved to one piece molding. A single tool is built to lay up both hulls and the bottom of the bridgedeck connection in a single large piece. The fundamental strength of the build is higher, allowing for less expensive materials to get the same strength.

“One piece” is a slight misnomer, as the top of the hulls and decking is built in a second mold which is laid over the hulls and bonded along the joint near the top of the hull molds. The loads on a join between the bottom hull and top deck are considerably lower than those on the bridgedeck. There’s no real twisting and torsion on that part of the boat relative to the join between the hulls, so it can be laminated without the same concerns as building between the hulls. ( Editor’s Note: Some builders mold the bridgedeck and inboard half of the hulls together and then mold on the outboard halves of the hulls and deck on top. There is a seam running stem to stern centerline along the bottom of each hull with this technique. )

There are a number of production and build advantages to this approach. Though the tooling is larger, more expensive and awkward, the lay up process incorporates the core hull joins in the initial build. You don’t have to line anything up and glass it in place when your hulls and deck are built connected. There isn’t need for as much material buildup to shore up the “box” since it’s part of the integral build.

Fitting the interior joinery and finish is more challenging, since the crossbeams and related components must be built early in the process. Extra care and planning in the design process can make this more efficient, but access to internal areas of the hull can be difficult during the build.

Alternative Materials – Wood and Metal

Composite construction – fibers and resin – lets builders make nearly any shape. Fiberglass has allowed for the wide range of affordable to high end production catamarans available today. Stronger fibers and better resins have only expanded the possibilities for light, fast, and strong boats.

Wood is rarely used for structural elements in modern production catamarans. It can be heavy, and it doesn’t lend itself to the complex molded shapes designers demand for optimal strength and seaworthiness. Plywood may be used for stiffening in places, and balsa cored decks may still be found. But mostly in older boats, home builds, and kit boats.

Metal construction has its own problems, and very few catamarans are built from metals. Curved shapes are difficult with metals; bending a smooth radius into a flat sheet without bending it, then welding it into place requires time and skill. And weight will be a problem. On the whole, fiberglass is a better solution for a light, strong catamaran.

Conclusion: Tying it Together

This overview only touches on some of the challenges multihull builders face, which monohull builders do not. But what does it mean for you when you’re looking at catamarans to buy? All the fiberglass build techniques will result in a strong boat if built properly. There may be differences in the amount of materials used, and choices for resins and fibers, but the boat should be evaluated as a whole.

It’s good to understand how your boat is built, and to be aware of some of the strengths and limitations of each build technique. But no build technique is inherently better or worse than the other – no matter how your next boat is built, the designer and builder will ensure the build is up to the task.

• Tags Buying Advice

By BJ Porter

Owner of Hallberg Rassy 53; world explorer.

7 replies on “Catamaran Structure – Bridge Decks and Cross Beams”

Proof read much? But the no build technique is inherently better or worse than the other… Good article spoilt by miss spellings and errors.

I corrected the extra “the” you mention in that sentence. I do not see other errors. We do our best and thank you for reading and commenting.

Great article. Very informative for us non-technical types. Great use of graphics and photos to explain the various torsion forces and different build methods. What is the purpose of the wing-like, rear spoiler-looking feature that you sometimes see spanning across the back of the deck/bridge and sometimes connecting the two hulls?

It doesn’t actually connect the hulls, it rests on them. In the good old days this was named a “RADAR Arch” and was used to mount the RADAR antenna and dinghy davits.

Over the last 20 years this stern “ARCH” became a very convenient spot to mount RADAR, solar panels and it is in this role it serves very well while also handling various antennas and of course, the dinghy.

Thanks for the article, great stuff, very informative and useful info. Kudos

I’m actually researching and trying to figure out how to build my own catamaran. But information is very hard to find.

Within the past few weeks I saw an illustration (photo?), of a pair of new catamaran hulls, with almost a full-length, flat bridgedeck connecting the length of the upper-inner edge of each hull. (I’m assuming it’s relevant only for a party-or-barge-type, power cat, to be completed by the buyer. I believe they were saying they can offer this bare-bones, hulls-and-bridgedeck package for about 40′ to 70′ lengths.

Any idea who may be offering this? I only skimmed the advt, but I think (??) it was a U.S., east-coast company. Now I’m seriously interested.

Much Thanks R.S.G.

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MIKE WALLER 

Yacht design.

WALLER 880  CATAMARAN

Designed by Mike Waller

The WALLER 880 Cat is a full length bridge deck catamaran designed for family coastal cruising, with the occasional foray further afield. Full length bridge decks have several advantages in smaller cats, in that they provide a stronger hull structure, more deck space, are easier to construct and eliminate the need for expensive bow beam structures. They also eliminate bow netting which needs to be maintained and replaced on a regular basis. Pounding in heavy weather is minimized by keeping the bridge deck clearance as high as practical in a vessel this size. It should be noted that vessels of this configuration have safely completed the longest ocean voyages, including circumnavigations. An ideal boat for the amateur boat builder.

L.O.A.                                    8.88 Mtrs

L.W.L                                    .8.45 Mtrs

Beam                                     4.96 Mtrs

Draft0.                                      80 Mtrs

Displacement                          3105 Kg

Hull Length / Beam                 9.18 to 1

Sail Area                      50.84 Squ Mtrs

Payload (Ave)                         1000 Kg

Payload (Max)                        2000 Kg

Note# All displacement and payload weights above are as per designed plan, and cannot be guaranteed.

The Waller 880 is designed for safe, comfortable family cruising, with bunks for 4 in seperate cabins, and room for 2 more on the dinette in an emergency. It also features a large, functional toilet / shower area, a full size chart table, a large galley, and a huge cockpit for socializing. There is excellent headroom throughout, with over 2 metres in the working hull areas and 1.5 metres over the bridge deck sitting / sleeping area. simplicity and ease of construction the hulls are strip planked in cedar and glass composite. The bulkheads, deck and cabin utilize plywood for cost efficiency, but can be constructed from composite panels if desired. The entire vessel uses timber / epoxy construction, with virtually no additional internal framing. The rig is a simple but efficient 3/4 sloop, with a large sail area for light weather cruising, easily reefed in heavier weather. Auxiliary power is from an outboard engine in a seperate pod beneath the bridge deck. This works remarkably well, and the 880 is very manouvreable under power. vessel features small stubb keels for cruising simplicity, and efficient spade rudders for positive helm control. Steering as designed is by tiller, although wheel steering could be fitted as an alternative.

BUY YOUR PLANS HERE

Please read this before ordering plans

Study Plans  $25.00

Full plans  $850.00,  click on any photo for larger image and information .

Did you know? #1 Bridgedeck Clearance

Among the factors contributing to the comfort at sea, you will find the bridgedeck clearance. Why? Because this height above the water, depending on its importance, will increase the seaworthiness. Just like the hull thinness, this height will prevent the boat from slamming on waves. When waves are slamming under, not only it’s unpleasant to hear, but it also slows the boat down!

Next time you will be walking on a pontoon, watch carefully the cats you will see, and get a chance to check this height. It will tell you a lot on their comfort…and efficiency!

Bridge deck clearance ratio (BCR) starts to be good from 6% of LOA.

On our models, the bridge deack clearance is as follows:

• ORC50 : 37,4 inches
• ORC57 : 42,1 inches

Should you have any questions about other measures, or want to know more about our boat specs, please let us know !

Speak to you soon.

Fair winds,

The ORC Team

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What Is a Cruising Catamaran? Everything You Need To Know

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There’s nothing quite as exciting as sailing the open sea. One of the most popular boats today is the cruising catamaran. If you are interested in cruising, whether you’re a passenger or a sailor, it’s worthwhile to learn more about the cruising catamaran. 

A cruising catamaran is a double-hulled vessel that is used for ocean crossing. They are designed for long-distance journeys and can carry a significant load while maintaining high speed and stability. Cruising catamarans have a range of passenger facilities and amenities. 

This article explores everything you need to know about cruising catamarans, from their physical features to their sea performance. It explores their different types and examines why they are such popular cruising vessels. It will also give you an insight into some of the most popular cruising catamaran brands and models on the market. 

Table of Contents

Design and Features of a Cruising Catamaran

In their present form, Catamarans can trace their history to more than 200 years ago when used in Taiwan and other Asian countries. Their chief defining feature is that they have two hulls. There are currently two types of cruising catamarans on the market: sailing catamarans and power catamarans. 

• Sailing catamarans: Sailing catamarans rely on the wind to move. They are ideal for sailors who want to try their hand at harnessing the wind to power and navigate their catamaran. However, if there is little to no wind, sailing catamarans will not be able to go very fast.
• Power catamarans: Many passengers and crew prefer a power catamaran, which does not rely solely on the wind for power. Instead, power catamarans are powered by fuel, but can still cruise when there is no wind. They also tend to be larger than sailing catamarans and have more spaces for passengers to lounge in.  

The two hulls are the defining feature of a cruising catamaran. However, there are several other design elements and technical features that both a sail and power cruising catamaran may have. These features and design aspects are explored below. 

Basic Layout

Several areas and spaces are in the same location in all cruising catamarans . For instance, the main deck is typically the home to the cockpit and the saloon. Meanwhile, the space below the main deck houses the stateroom and the headroom. 

However, other features and spaces, such as the galley and the helm may be located in different places, depending on the cruising catamaran model. 

The size of cruising catamarans also varies depending on the model. Catamarans between 32-36 feet (9.75-10.97 m) usually have two cabins, while catamarans that are between 36-50 feet (10.97-15.24 m) have three or four cabins. Models that are more than 50 feet (15.24 m) long may have five or more cabins. 

Steering Stations

The steering stations or helm positions can be in one of several places aboard the cruising catamarans. Each position has unique advantages and disadvantages. Some common helm positions include the aft position, the flybridge position, the off-set helm, and the forward helm.  

Aft Position

When in the aft position, the helm is located in the cockpit and allows for excellent visibility on either side of the sail. It will enable the helmsman to engage with passengers in the cockpit and saloons. However, helms in the aft position are not weather protected and may be vulnerable to rain and storms. They only have room for two people, which may be inconvenient for a larger crew.

Flybridge Position

On some cruising catamarans, the helm is located on a second-story flybridge. A second-story flybridge allows for a higher vantage point of the surroundings, which is especially useful when docking in small spaces. However, the view can be obstructed when the headsail is raised and when the captain wants to check the sail trim. Also, an added flybridge for the helm may add windage and weight to the catamaran, resulting in reduced performance. 

In rough weather, steering on the flybridge may be uncomfortable for the helmsman due to the additional height making it pivot and swing much more. They may also be too far from the crew and passengers on the catamaran, which may be dangerous in an emergency. 

Off-Set Helm

The off-set mid-level helm or the mezzanine helm addresses many of the flybridge’s and the aft helms disadvantages. Placed halfway between the cockpit and the coach roof, this helm position is close to the saloon and cockpit. 

This position allows the helmsman close contact with the passenger and crew. This helm location also has good visibility on one side of the sail and can seat up to 3 people. However, the off-set mid-level helm doesn’t have any visibility on the other side of the mainsail once it is raised. 

Forward Helm

A helm that is sometimes found on cruising catamarans is the forward helm. This helm is located at the front of the catamaran, between the mast and the cabin. There is excellent visibility forward from this location, and it is close to the saloon. However, this helm can be challenging to protect in bad weather, and it may be difficult to dock the catamaran as the helmsman won’t have far-reaching visibility. 

No matter the helm’s location, all modern cruising catamarans have autopilot built-in.  

Bridge Deck Clearance

Bridge deck clearance refers to the height of the bridge deck (underside of the cabin, in between the hulls) above the water. Cruising catamarans should have a high bridge deck clearance.

If the bridge deck clearance is too low, the waves may pound against the bottom of the bridge deck. This pounding can cause discomfort and fatigue for the passengers and crew and potentially reduce the catamaran’s speed. 

The height of the bridge deck clearance needs to be proportionate to the hulls of the catamaran. It should be a minimum of 20% of the space between the hulls. 

Shallow Draft

A boat draft refers to the minimum amount of water needed to float a vessel without the bottom of it touching the ocean bed. Cruising catamarans have a shallow draft—they can stay afloat in water less than 4 feet (1.21 m) in depth.

This makes it possible to go really close to shore( how to beach a cat ) and sail places where no monohull can go.

Galley Locations

Cruising catamarans have their galleys (cooking areas) in one of two areas. The ‘galley up’ is when the galley is situated next to the saloon. Those working in this galley can see the crew as they cook and can also see the sea and horizon beyond. 

Meanwhile, the ‘galley down’ is when the galley is located in the catamaran’s hull. This galley location separates it from the saloon area, allowing for more space and maneuverability in both the galley and the saloon. However, this may be isolating for the people who are working in the galley. 

Why Choose a Cruising Catamaran?

Cruising catamarans are not the only vessels that are used for cruising. Cruise ships are the vessel of choice for lengthy ocean cruises that carry hundreds or thousands of passengers. 

However, cruising catamarans are the vessel of choice for smaller, more intimate cruise experiences with a maximum of 15 passengers. They are superior to boats with only one hull, and offer a range of other benefits for passengers and crews alike. 

Speed and Safety

Cruising catamarans can be 25-30% faster than their monohulled counterparts of the same length.   

These vessels also tend to heel (tip to one side) less than a watercraft with one hull. Because of this, the crew finds the cruising catamaran more comfortable to sail in rough weather. Thanks to the cruising catamaran’s speed advantages, the crew can also move quickly out of an area about to be hit by bad weather. 

Closed-cell foam fills many spaces in a cruising catamaran. This gives most parts of the vessel extra buoyancy. Even if the catamaran tips over or breaks apart, most of the vessel will float, allowing crew and passengers to remain floating on the surface of the water as they wait for rescue service. 

Read this article on “when and why catamarans capsize” .

Very Spacious

Many cruising catamarans models have a significant amount of space, much of which is placed above the deck. This space can be used for various passenger amenities, including a salon, cabins, and a galley.

Thanks to the amount of space available, there are plenty of passenger and crew facilities and amenities available. Larger cruising catamarans can have 4-5 cabins, 8-10 berths, and up to 4 toilets or shower facilities. 

The galleys in these catamarans have room for a range of amenities, including a dishwasher, coffee machines, and other cooking equipment. 

The crew also benefits from the space in cruising catamarans as there is more room in the cockpit and a large amount of deck space. 

Stable and Easy To Maneuver

As they have two hulls and therefore a broader base, cruising catamarans are much more stable as compared to mono-hulled vessels. 

Cruising catamarans can hold their own against rough waves—even in the face of a stormy sea, the upper deck of a cruising catamaran will not rock too much. Therefore, passengers can walk on the upper decks comfortably—this is especially beneficial for young children or elderly passengers. Thanks to the cruising catamaran’s stability, it is easier to do activities like cooking and cleaning. All in all, cruising catamarans make for a more comfortable living! 

Compared to monohulls, cruising catamarans are also more maneuverable. They can be turned 360 degrees within their length and are easy to dock because they have two motors and two rudders making them easier to steer. 

The cruising catamaran’s shallow draft allows the crew to take it into significantly shallow regions. This is great because it increases the areas that the crew can access and explore. 

Drawbacks of Cruising Catamarans

Cruising catamarans are appealing to both passengers and crew for a range of reasons. However, it is also essential to consider and prepare for some of the drawbacks of cruising catamarans . 

Cruising catamarans require a significant amount of space to dock because of their length and hull size. It may be hard for the crew to navigate a large cruising catamaran into a marina with limited docking space. Due to the additional space they need, it will cost more to dock cruising catamarans. 

It will also be more expensive to charter, rent, or buy a cruising catamaran as compared to a monohull. It may cost 200%-300% more to charter a cruising catamaran as compared to a yacht of the same size. 

Because of their appeal, cruising catamarans are significantly in demand in some areas. It’s essential to book a cruising catamaran well in advance if you’re looking to enjoy a sea cruise.

What Are Some Popular Cruising Catamaran Models?

If you are looking to charter, rent, or buy a cruising catamaran, it is worth examining some of the most popular models and brands currently on the market. Some of the best companies that manufacture or have manufactured cruising catamarans include:

Each of these companies sells one or more high-quality cruising catamarans. Some specific cruising catamaran model suggestions can be found below. However, if you are looking to charter or buy a cruising catamaran, take some time to explore a range of specific models in addition to the following ones. 

Looking to buy a catamaran? check out my list of Best catamarans under 200k USD .

Nautitech 47 Power

The Nautitech 47 is a powerful, modern vessel with a range of attractive features for owners, crew, and passengers. 

Depending on your preference, the Nautitech 47 can have 3-4 cabins and 6-8 berths. The number of cabins in this catamaran can easily be adapted by closing (or opening) a few doors. This versatility makes the Nautitech 47 excellent for entertaining. 

The flybridge can be wholly enclosed, which is great in bad weather conditions. 

A used Nautitech 47 power catamaran can cost between $800,000-$100,0000. Nautitech 47s that are currently on sale can be found here .  

60 Sunreef Power

The 60 Sunreef Power is a luxury catamaran that can easily be customized and is easy to maneuver and program for navigation. 

One of the most enticing features of the 60 Sunreef Power is that it can be operated with and without a crew. It has an advanced navigation system, where the helmsman can program in the desired destination, speed, and other information. The in-built system will then use autopilot to navigate. 

The 60 Sunreef Power is also extremely spacious. It is 60 feet (18.3 m) in length and can host up to 12 guests. There’s a variety of spaces for guests to lounge on, including the semi-open saloon, the main deck, and the aft cockpit. 

A 60 Sunreef Power can be bought either new or used for around $1,700,000 USD . 

Manta is a well-known brand for designing and building high-performance catamarans. A popular cruising catamaran that Manta produced in the 1990s and in 2000 is the Manta 42. There are several Manta 42s that are still being used or sold. 

The Manta 42 is popular as it has a large amount of space and an excellent sail-area-to-displacement ratio . However, it is also vulnerable to stress cracks in the bow area. It’s also important to note that the berth area in Manta 42 is small compared to more modern catamarans. Taller passengers may also have to stoop slightly to enter its saloon. 

There is a dedicated owner’s association for Manta models, including the Manta 42. The owner’s association is evidence of the Manta 42’s popularity and is also an excellent place for cruising catamaran owners to connect. 

A used Manta 42 can cost between $200,000-$300,000.

Looking for catamarans under 200k?

Other Types of Catamarans

While cruising catamarans are the watercraft of choice for leisure cruises, there are several other catamaran types. Some popular catamaran types are:

• Racing catamarans: These catamarans are designed for racing and long-distance and endurance sailing. They often have full-length battens on the mainsail and a rotating mast. There are also very small catamarans called beach cats, these can typically be launched from and landed on a beach.
• Whitewater catamarans: Used in whitewater rivers, the whitewater catamaran has an aluminum or a tree trunk base and two inflatable hulls with inflation holes. These features allow these catamarans to move quickly through the water. 
• Military catamarans: Some countries’ navies use catamarans for transport. For instance, the US Navy owns and operates Expeditionary Fast Transport catamarans to transport cargo quickly. 

However, while there are several different types of catamarans, sailing catamarans are arguably the most popular for long-distance cruising. 

Cruising catamarans are very common vessels used for long-distance sailing, sometimes around the world . They have a variety of benefits as compared to other cruising vessels. While cruising catamarans’ design and size may differ, most are relatively spacious, stable, and easy to maneuver. They also have a range of facilities and amenities for passengers. 

Several companies design and make high-end cruising catamarans, including Manta, Nautitech, and Sunreef. However, there is a vast range of cruising catamaran models on the market ranging from 20 000 USD up to 1 000 000+. 

With this foundational knowledge, you are now better equipped to delve deeper into the world of cruising catamarans. 

Owner of CatamaranFreedom.com. A minimalist that has lived in a caravan in Sweden, 35ft Monohull in the Bahamas, and right now in his self-built Van. He just started the next adventure, to circumnavigate the world on a Catamaran!

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open bridgedeck catamaran design

Discussion in ' Multihulls ' started by BobH , Apr 17, 2015 .

BobH Junior Member

Looking for commentary/critique (aside from, "don't design it yourself"). I have put together a design for a catamaran to meet my list of requirements: 1. catamaran, max 34 ft. LOA, 21 ft. beam 2. good bridgedeck clearance…32 inch minimum 3. minimum open bridgedeck, well back from bow and stern 4. center of gravity at or below bridgedeck, with all tankage, engines, food storage near waterline 5. epoxy-cedar strip hull bottom/ply on frame above (as in Woods Sagita/Eclipse) 6. inboard diesels, kick-up drive legs, good fuel capacity (motorsailer…modified Sillette Sonic-sideways mounted engine in each hull-no universal joint) 7. easy-to-handle, easy to balance sailplan...Ketch - main: vertical roller reefing (as in the wishbone gaff rig by Bernd Kohler), freestanding mizzen: sleeved sail with wishbone boom and gaff, jib: roller reefing 8. balanced rudders 9. daggerboards 10. accommodations for four: small galley, drop-down table, enclosed head, two large double berths 11. capable of offshore runs from Alaska to Chile and Hawaii, but mostly summertime sailing in NW Pacific coastal waters I am looking for some helpful observations/advice. I would like to do as much of the legwork of layout and design myself, including the basics of sail CE vs. CLR, distribution of weight, etc., but I do plan to engage a qualified naval architect to finalize the structure. For what it's worth: I enjoy designing what I build.  

Attached Files:

Petros Senior Member

That looks like a very nice design, well thought out. I love the way you integrated the central salon with the hull berths. My personal preference would be on a 34 footer to use a sloop rig, less rigging and stuff to mess with and maintain. And I would also go with a plumb or vertical bow, it will have slightly less tendancy to dive and might give you a dryer ride than the racked back bow. To my eye the rudder sees a bit smallish, though that is without knowing any of the areas or ratios. Good luck.  

snowbirder Previous Member

I'd prefer a sloop on a boat of this type/size as well. Also... if your boards are up, those rudders hit the ground first. They need to be able to deal with hitting the ground and not breaking. Kickup or something.  

waikikin Senior Member

snowbirder said: ↑ I'd prefer a sloop on a boat of this type/size as well. Also... if your boards are up, those rudders hit the ground first. They need to be able to deal with hitting the ground and not breaking. Kickup or something. Click to expand...

John Perry Senior Member

I find this interesting, particularly since about 3 years ago I got some way into drawing a cruising catamaran which shares many features with your design - roughly similar overall dimensions (mine is a little smaller) - very similar proposed construction method (strip plank hull bases, plywood elsewhere) - open bridgedeck but with provision for storage and a wheel with seated helm position - similar continuation of the in-hull accomodation into the bridgedeck - very similar arrangement of the main entrance hatches into the hulls. Differences are that I drew a sloop rig, although I did not get as far as finalising the details of this, also mine was intended to be primarily a sailing boat rather than a motor sailer and as such it would have outboard engines, not diesels. I think your design looks to be well thought out, here are a few comments: Are the lines that run from the windward hull to the outer ends of the wishbone gaffs intended to control sail twist? This is the way 'vangs' were used to control sail twist on the spritsail barges that operated on the Thames estuary in the UK in the early decades of the 20 century. If this is so, it is an interesting idea and one I have wondered about at times. Although most mainsails probably do twist more than the optimum amount, some twist is desirable to lower the center of effort in wind gusts and it can probably also help to reduce induced drag. I suspect that over-restricting twist at the head of the sail would not be good. I also see a potential problem with combining the mizen gaff vangs with an unstayed mizen mast. The unstayed mast can be expected to bend away to leeward in gusts so if the outer end of the gaff is restrained by vangs a wind gust may well cause the angle of attack to be increased towards the top of the sail which I would have thought highly undesirable. With regard to the vangs on the main gaff, I wonder if a simpler way to control that gaff would be a line taken from a sheave at the top of the mizen to the outer end of the gaf, although I realise that would mean that the two masts would be tied together so that if one were to fail both probably would. I dont understand why you have a wishbone boom on the mizen but not on the main. Wishbone booms have been found to work well, so if you are going to have one on one sail why not on the other? Also, if you do want a boom on the mainsail, why does it need both a rigid kicking strap and a near semi-circular mainsheet track - I would have thought one or the other and if you go for just the mainsheet track you could still have a topping lift and possibly also lazy jacks to hold up the boom. I would have thought that you might want a roller foresail, maybe this is just not shown at this stage (my drawings also show very little detail of the rig). The deck area around the base of the main mast is sloped so may not be a good working area, but its no worse than on many other catamarans. Since you dont have accomodation in the area of the mast step I would have thought it would be possible to have at least a small flat working platform to handle halyards etc. at the base of the mast. Your proposed engine arrangement sounds very good for a motor sailer - if the outdrives are steerable you could even make the boat crab sideways into a parking space without the need for any bow or stern thrusters. However, it does sound like an expensive solution requiring quite a lot of custom engineering. I imagine that you will need to have bevel gears between the engine and the input to the outdrive leg, perhaps these would be fitted into streamlined 'blisters' on the inner topsides. The picture attached shows a possible alternative way to drive a retractable propeller from a transverse mounted engine - obviously an old idea! If the bevel gears are fairly near the waterline on the outside of the hull would not need nearly such a long shaft and the perhaps the shaft could swing down on a pivoting bracket. Just a thought. This being a motor-sailer I am surprised that you do not want the helm position fully sheltered, at least from ahead. A fold down windscreen/spray dodger could achieve this if it were not for the curved mainsheet track that would be in the way of it. It looks like you are intending to place the topside stringers on the outside of the boat. Certainly an interesting idea - should avoid the stringers taking up space in the accommodation and they should provide some protection for the topsides, sounds good. The drum mounted rudders should be feasible. At one stage in my rather varied career I worked for a small company that made specialist hardware for racing yachts and sailing super yachts. One of our projects, albeit not one that I was closely involved with, was a rudder in a rotating drum as you have drawn. This was for a monohull race yacht, I think the designer was Julian Everett, he might even have some information about it. As far as I know it worked fine, but it was quite a job to make - I think we had big custom made ball races at the top and bottom of the drum, Torlon balls and I think the races were non-metallic, maybe turned from something like Tuffnell, I cant quite remember the details. I dont want to divert this thread, but for comparison I attach a drawing of my one - not even a finished design at this stage. I got this far with it then started to get ideas for a novel lifting hydrofoil arrangement which would probably be best tested first on a smaller boat, or perhaps I should do like Doug Lord and start with a remote controlled model.  

Dutch barge.jpg

Mr Perry, Apparently we do have some similar ideas regarding design features. Excellent drawings...what software are you using? Yes, those are vangs. I am experimenting with the idea of using a stiff freestanding mast with a vang with a controlled stretch device (like the rubber band links used in exercise machines for resistance in place of weights). The vang would have a slack loop in it held slack by the bands...at full stretch the rope takes over and the vang is full on. I plan on trying a scaled down version of this rig this summer, if I can get the rig and boat done (15' double-ended sail/row boat). Sort of an adjustable, self-resetting circuit breaker for dealing with gusts rather than a quick hand on the vang. The force applied can be adjusted during trials by adding/reducing resistance. I want to avoid having to rebuild a carbon mast because the first try was too bendy. Using a freestanding mast on a multihull is not suggested just because of the huge righting moment...so I thought I should have some safety feature as part of the design in place of the customary engineering safety factor arrived at by tripling the forces designed for. This boat will have a righting moment of approximately 64,000 lb ft. A mast strong enough to handle three times that would be too fat and too heavy. So I want sail controls that will dump wind in a controlled way...adjustable as experience with the boat dictates. Because the mizzen is freestanding I do not want them linked...I agree, it would be a good angle for main twist control to take a line from the mizzen top...but too much stress for the mizzen to bear at the partner. As it is the mast has to be able to lift the leeward hull with a force centered at the CE for that sail. As far as I can calculate, adding the possible force due to the main at the very top would require too much of the mizzen (if it is of reasonable diameter and weight of construction). The rig is an amalgam of a freestanding version of a Wharram cat rig with Bernd Kohler's vertical furling main...hopefully done well. First reef: douse mainsail...40% reduction, CE shifts very slightly aft and down, 2nd reef: roll in some foresail and first reef mizzen...and so on. Hopefully the rig has the reported good manners of cat-ketch rigs like on a Core Sound 20 or Presto 30. Right, spiral bevel gearbox...good friend machinist/mechanic is willing and able to put the drive together. We'll also be able to put together the box cooler and dry stack exhaust system. Regarding the dodger...the freestanding mizzen is able to rotate 360 degrees. I don't want to limit that. The topsides are to be sandwich construction with inner layer 4mm ply, 3/4 in. stringers with core between, finished in 4mm ply, with fir stringer doublers outside then glassed. Sounds complicated, but not really. I hope to build the panels into one piece and attach the inner stringers on the floor, then hang the whole side in one go (with lots of careful measurements and plenty of help). Fill the spaces between stringers, fair, then the outside panel with its stringers already attached providing stiffness to the floppy 4mm panel. We'll see. Rudders...you are right...in drums with plastic bearings. I want to distribute rudder forces over a much larger bearing surface and still have them retractable. Rudders built to break before the drums do...carry spares.  

brian eiland Senior Member

Single-Masted Ketch consideration BobH said: ↑ Looking for commentary/critique (aside from, "don't design it yourself"). I have put together a design for a catamaran to meet my list of requirements: 7. easy-to-handle, easy to balance sailplan...Ketch - main: vertical roller reefing (as in the wishbone gaff rig by Bernd Kohler), freestanding mizzen: sleeved sail with wishbone boom and gaff, jib: roller reefing Click to expand...

BobH said: ↑ Mr Perry, Apparently we do have some similar ideas regarding design features. Excellent drawings...what software are you using? Click to expand...

Roller main Here's a link to an article on the roller main: http://www.duckworksmagazine.com/13/columns/guest/bernd/#.VTkhENJVhHw  

Rudder drum "You dont have the rudder drum axis perpendicular to the hull skin, so when the rudder turns you will have a step in the underside of the hull, presumably you know that and dont mind it." Yes, that is a problem...my solution is to not make the bottom of the drum flat. Rather make it curved in cross-section close to the longitudinal cross-section of the hull bottom in that area...like a bowl bottom. So it presents a fill for the cut out for rudder motion +- 35 degrees  

rudder1.jpg

Rudder2.jpg.

The core will be structural. I am working on the same principles shown in Gougeon's West System book...they often used both stringers and core, apparently (like on Rogue Wave's deck). For the outer layer I may even try laying down a flat fiberglass sheet on a melamine table on the floor in one piece, glue on the outer stringers, and then secure that sheet to the structure so I can visually inspect the bond through the glass (would have to be as thin as workable...probably would need to set up a low vacuum clamp on the whole side). Then, when it is set, overlay an appropriate layer of outer glass (right now I am thinking 40 oz total of uni and biax). So there would be only the inner layer of wood...the outer layer of FRP. I'll have to experiment with that first to see if it has a chance of working. The outer stringer is dual purpose...both protection from damage to the skin and to provide some stiffness in the FRP outer layer...like a hat section stiffener. So it is to be used on both sides of the hulls.  

Anchor lead The bow fittings are for an anchor bridle. The chain and anchor are stowed on a capstan at the rear of the bridgedeck. The idea is to deploy the anchor then bring the last bit of chain up to the bow to secure the bridle. A rope from the capstan to the bow does that last bit.  

Mr Perry, What tool do you have for an FEA analysis? I am new to this forum...I will try to link this thread to the multihull section....not sure how right now.  

Fat-Headed, Squaretop Sails I know they are all the rage, but there are some questions about their use. I think there are some subject threads on this forum about that subject. Here is one: http://www.boatdesign.net/forums/sailboats/squaretop-mains-46803.html Most recently I added a question about which sail resulted in the capsize of the latest foiling Gunboat: brian eiland said: ↑ I would make note of the 'culprit sail' that most contributes to the final capsize.:?: https://vimeo.com/125378004 (I don't think its that big reacher that's almost acting like a genoa at these relative wind speeds,....I think its that mainsail,...that's suppose to twist off to relieve that pressure at its head ) Click to expand...

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tspeer Senior Member

John Perry said: ↑ ...The idea of using elastic elements to relieve sail forces in high winds is one of those ideas that is pretty obvious but doesn't seem to have been looked into much, perhaps there is a reason for that. ... Click to expand...

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Waller 880 by Mike Waller Yacht Design

29 ft cedar strip / glass bridgedeck catamaran.

URL: http://wallerdesign.com.au/wal880.html

Description:

The WALLER 880 Cat is a full length bridge deck catamaran designed for family coastal cruising, with the occasional foray further afield. Full length bridge decks have several advantages in smaller cats, in that they provide a stronger hull structure, more deck space, are easier to construct and eliminate the need for expensive bow beam structures. They also eliminate bow netting which needs to be maintained and replaced on a regular basis. Pounding in heavy weather is minimized by keeping the bridge deck clearance as high as practical in a vessel this size. It should be noted that vessels of this configuration have safely completed the longest ocean voyages, including circumnavigations.

The Waller 880 is designed for safe, comfortable family cruising, with bunks for 4 in seperate cabins, and room for 2 more on the dinette in an emergency. It also features a large, functional toilet / shower area, a full size chart table, a large galley, and a huge cockpit for socializing. There is excellent headroom throughout, with over 2 metres in the working hull areas and 1.5 metres over the bridge deck sitting / sleeping area. simplicity and ease of construction the hulls are strip planked in cedar and glass composite. The bulkheads, deck and cabin utilize plywood for cost efficiency, but can be constructed from composite panels if desired. The entire vessel uses timber / epoxy construction, with virtually no additional internal framing.

The rig is a simple but efficient 3/4 sloop, with a large sail area for light weather cruising, easily reefed in heavier weather. Auxiliary power is from an outboard engine in a seperate pod beneath the bridge deck. This works remarkably well, and the 880 is very manouvreable under power. vessel features small stubb keels for cruising simplicity, and efficient spade rudders for positive helm control. Steering as designed is by tiller, although wheel steering could be fitted as an alternative.

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Bridgedeck Slamming

People are right to be concerned about bridgedeck slamming on catamarans. Having said that, it is usually a comfort problem rather than a structural one. Fortunately it is, or should be, a thing of the past.

Early catamarans had low freeboard, partly because of the heavy materials which were all that were available at the time, and also because low freeboard boats always look better. The latter is still true today of course, but people have now got used to seeing high boxy catamarans.

In an attempt to cushion the slamming, many builders, and Prout Catamarans in particular, developed the central nacelle. Prouts took this nacelle to it's extreme and their last designs were more like three hulled catamarans with the nacelle in the water at rest. I took this photo (below) when cruising in Venezuela. A Prout is in the foreground while a conventional high bridgedeck catamaran is in the background.

I have never believed this approach to be a good one. I always say that for offshore sailing one should be able take a conventional inflatable dinghy under the bridgedeck. I sailed the S Atlantic from Capetown to Rio in a Norseman 43. Its bridgedeck was very low (but it looked a very nice boat due to its low freeboard) and it was very uncomfortable living on board. A few years earlier I had sailed from the UK to the Canaries in another low bridgedeck catamaran (again not one of my designs). The slamming was so bad that we were unable to use the saloon table as plates would jump off as we hit every wave.

The Gemini 105 has a notoriously low bridgedeck, in part to keep freeboard hence weight hence costs down. We have been kept awake by the slapping from one that was anchored next to us, while this from one of my customers "I was aboard a 105 last week in Waderick Wells, Bahamas, and was unsure if it was polite to break conversation whilst she slammed while on a protected mooring, or pretend it wasn't happening as I guess their dealers must?"

I took the photo, below, while sailing in the Greek islands. This is a large (over 45ft) catamaran but I do not know what design. Clearly there is not enough bridgedeck clearance!! Yet if you look at the transoms they are still out of the water, so the boat cannot be considered overloaded. A boat like this should have at least 600mm clearance - implying at least 500mm (18in) more freeboard is needed to make it safe and more comfortable. This is not a boat to take to sea, no doubt it was bought because the owners liked the space below and they never took it for a test sail before buying.

Much of this slamming is self inflicted. Imagine two hulls close together pitching into a wave. The water they displace has to go somewhere, and it piles up just as the bridgedeck sails over it. Clearly a wider hull spacing will turn a narrow high peaked mountain of displaced water into a low flat molehill. A wide knuckle and flared hull will also help reduce the size of the induced wave.

The best solution is to start the bridgedeck well back and have it low only where needed. That's why most offshore catamarans have nets or trampolines forward. The boats to avoid if you plan any offshore sailing are those with bridgedecks taken right to the bows.

Furthermore, the water that goes in at the bow also has to come out at the stern, for as the bows pitch out of a wave the sterns will pitch in. So bridgedecks should also be high near the stern. Have a look at the stern of a Prout catamaran, you'll see there is very little space for the bows waves to get out. No wonder they are so noisy to sail - and the waves trying to force their way out must slow the boat down.

I do fit a nacelle on some of my designs, notably on the Gypsy and Romany. I accept the compromises as I wanted standing headroom in a small boat. But I designed these nacelles as footwells so they are as small as possible, (they are only 600mm/2ft wide). I sailed my own Gypsy and Romany thousands of miles and didn't find slamming to be a problem. Mind you, I also had a Veed bottom to the nacelle. Had it been flat then I am sure the slamming would have been noticeable.

So my newer designs (like Transit, Vardo and the powercats) don't have a flat bridgedeck bottom, it's slightly Veed

Of course the smaller the boat the bigger the problem. That's why I don't have any bridgedeck cabin designs with full headroom under 30ft. If you have 6ft headroom on  a 30ft boat then scaling it up to 40ft would give you 8ft headroom - more than enough! So a 40ft boat can easily have over 2ft bridgedeck clearance yet still look in proportion

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Evaluating modern catamarans

Catamarans have been around, especially in the Pacific, for several thousand years. Early islanders sailed large twin-hulled canoes many thousands of miles, generally from Southeast Asia eastward to discover new island homes.

Modern multihull production started with the catamarans of Hawaiian Rudy Choy in 1947. The first cruising catamaran to circumnavigate was his World Cat in 1965. During the 1960s, Prout and Catalac of Great Britain were also starting to produce catamarans. Catamaran production took off in the late 1970s and early 1980s with French builders Fountaine Pajot, Catana, Lagoon and several others producing catamarans for the charter industry. Gemini also started building boats in the U.S. Soon afterward, South African builder St. Francis got started with a 43-foot cat in about 1990, and now a dozen others in South Africa produce about 30 percent of the world’s cruising cats.

After considerable research looking at a number of boats and more than four years aboard, full-time cruising in Southeast Asia, here are our thoughts on some important features to look for in a bluewater cruising catamaran.

Size vs. cost: As with all boats, as size increases, so does cost. We think a 42- to 48-foot cat makes a great cruising home. Any shorter, and sufficient load-carrying capacity for full-time cruising suffers; longer, and the hull and equipment costs skyrocket.

Bridge deck clearance (BDC): BDC affects the amount of noise in the boat from wave slap, especially while going upwind. We think a catamaran with about 30 inches of clearance is ideal. Increasing the BDC means more windage, which is a negative. Much less than 30 inches, and wave slap becomes a problem in rowdy sea conditions. Longitudinal under-bridge deck fins reduce wave impacts and strengthen the bridge deck. Reducing speed and falling off can also help minimize the problem. Consider how often you actually go close upwind in heavy conditions when cruising versus how much time you spend on other points of sail and in port. The St. Francis 44 has about 24 inches of BDC and it has completed many circumnavigations. However, that does not mean its BDC is ideal.

Load carrying capacity (LCC): Larger boats have more LCC for fuel, water, stores and equipment. Boats with finer hulls are faster than boats with fat hulls, but they will have less LCC. Most full-time cruisers will need at least 5,000 pounds of LCC. When asking this question, make sure you know the hull weight facts and what is included or not. Overloading a cat adversely affects speed, stability and BDC.   Beam-to-length (B/L) ratio and stability: For boats in the 42- to 48-foot range, the B/L ratio should be around 50 percent. Less than that will adversely affect stability in heavy beam winds, but larger boats can be okay with slightly less. A higher ratio adversely affects sailing characteristics. Most modern cats are in that range; older cats are somewhat narrower but also have shorter rigs. For more on this important characteristic, search the Internet for “catamaran stability.”

Integrity and quality of build: There is a big difference in build quality across manufacturers of catamarans. Things to look for include builder reputation, hardware quality and strength, use of lightweight construction materials, anodizing vs. painting of aluminum extrusions, interior woodwork finish, exterior design, and equipment quality and installation technique. If water enters older cats made of cored balsa or plywood, there are often maintenance problems. A good construction practice is to make the underwater hulls of solid fiberglass, and the topsides and decks of foam-cored fiberglass. Solid underwater sections are more impact resistant and easier to repair; they also make adding thru-hulls less of a problem. But they do add weight. If enough of the boat is made with lightweight cored fiberglass, the hull will not sink in case of a major collision or capsizing. This is a major catamaran safety feature, as it is always better to be upside-down on the surface than right-side up on the bottom.

Engine and power train: Having two engines is a major catamaran benefit. Engine and sail drive location on a lightweight catamaran affects pitching in a seaway, so a central location is better for weight distribution. However, a watertight bulkhead between an aft engine room and main cabins can prevent major flooding in case of shaft or sail drive damage. Engines under bunks or accessible only from aft deck hatches are a problem for routine maintenance and underway repairs, especially in rough weather. Sail drives simplify installations but aren’t as robust as a traditional transmission and shaft installation. From a maintenance standpoint, ensure you can perform routine maintenance easily and remove the engine from the boat if necessary. I consider our amidships engines ideal, but my wife does not agree that the galley is a good place for an engine.

Stub keels vs. daggerboards: Most cruisers prefer stub keels over daggerboards because they allow for drying out on the keel bottoms, can give extra tankage and a double bottom, include a deep bilge, and protect props and rudders from grounding damage. Daggerboards allow slightly higher pointing ability and speed in a narrow, upwind steering angle. However, the trunk and board are hard to clean and paint, the board is vulnerable to grounding and floating debris, and it can get stuck. Most modern catamarans built for cruising feature well-designed stub keels using NACA foil specifications.

Rigging and sails: In order to help prevent losing the mast if a standing rigging component fails, doubled shrouds and headstays are better than singles. We prefer mechanical wire end fittings because in case of a wire failure overseas we would be able to replace it ourselves. There should be sufficient winches to handle all sheets, halyards and reefing lines in an efficient manner. Pay particular attention to how easily reefing is accomplished. Can a light-air sail, a boom vang and preventers be accommodated? Will the mast height allow passage under the 65-foot height restriction for the U.S. inland waterways?

Helm placement: The primary helm station should be well out of the weather, have unobstructed visibility to all four corners of the boat, be quickly accessible from the cockpit, and have all controls and instruments available. Double helm stations, especially those aft on the hull decks and flying bridges, as well as those requiring looking through the saloon windows to see forward, can all be problematic. We think the best option is a single helm station on the forward cockpit bulkhead, well protected from wind and water, and with a good view in all directions — especially forward. Some modern catamaran designs feature a single-level main cabin overhead and cockpit top, which may conflict with the above desirable features.

Galley location: For those subject to seasickness, galley location can be a personal issue. But for cats less than about 48 feet, locating a large galley with adequate storage in the saloon is a problem. A galley, navigation/office station, dinette table and seating, and three entry/exits are all competing for space there. Further, an adequately sized and located navigation station, galley clutter and light contamination underway are potential problems in “galley up” boats. However, ventilation, crew interaction and seasickness issues are sometimes improved. Ideally, a large refrigerator, pantry and significant galley storage would all be co-located and on the same level with the galley. “Galley up” may be attractive, especially on weeklong charters with guests, but for the other reasons, we prefer the “galley down” arrangement for full-time cruising.

Navigation station: When full-time cruising, the navigation station becomes important for navigating, communicating and office use. Additionally, the circuit breaker panel, most electronics and battery/charging controls should be located there. Ideally, it would be positioned forward in the saloon with a comfortable seat and a good view forward.

Ground tackle: As one of the more heavily loaded systems on a cruising boat, high strength and no weak links are important for all ground tackle equipment. Look for double anchor rollers, strong bridle attachment fittings and good ground tackle storage arrangements. One of the better bridle attachment points is at the bow crossbeam to hull fittings. These should be exceptionally strong, and many boats have specially designed attachment fittings here. Ensure bridle-to-chain attachment fittings are full strength, removal can be done quickly, muddy chain can be washed effectively and that the chain locker is deep enough to minimize chain castles. The windlass should be robust enough to handle the boat’s ground tackle in at least gale conditions. Choose your anchors carefully; large scoops, like the Spade or Rocna, perform much better than older designs.

Decks: Uncluttered and relatively flat decks are preferred for safety at sea. Nonskid needs to be aggressive enough to ensure no crew slippage when wet. Fittings should be very robust and of quality construction. At least six large cleats should be very strongly mounted with large backing plates to spread out heavy loads. Many modern cats have little or no exposed teak — a feature I appreciate.

Bows and rudders: Bows and rudders should be strongly reinforced on their leading edges and designed so as not to catch lines and logs underway. Modern vertical and reverse stems, as well as spade rudders, have more of a problem with this than traditional skeg-hung rudders and bow shapes. Both keels and rudders should be designed to NACA specifications in order to perform efficiently.

Liquid capacities: For full-time cruising overseas, we think an onboard fuel capacity for a 1,200-nm range on one engine and about three weeks of water are ideal. At our average use of about seven gallons per day, about 150 gallons gives us more than 20 days of water. That is enough for many long ocean passages if there is no rain and the watermaker quits. Many modern charter cats have a large water capacity but a small one for fuel.

Watermaker: A large-capacity (approximately 40 gallons per hour) watermaker makes good sense in order to reduce the unit’s run time and the weight of stored fresh water aboard. Simple mechanically driven units are far less expensive, are less of a maintenance problem and can have higher capacity than 12-volt electrical units. We almost always are able to run ours when otherwise underway, so there is little need to run it at anchor — and most of the time we can collect sufficient rainwater anyway.

Refrigeration: As full-time cruisers overseas, we prefer a separate front-loading refrigerator for its convenient and quick interior access. However, the freezer needs to be top loading to provide good thermal efficiency. Capacities of up to 10 cubic feet for the refrigerator and 4 cubic feet for the freezer will provide good long-term storage. These are manageable for electrical energy usage, provided good system design and proper insulation values are used. However, many refrigeration boxes are deficient in insulation. The closer the refrigerator is to the galley the better from the cook’s point of view.

Cockpit covers: A well-designed solid cockpit cover should be able to prevent rain from entering the cockpit through the use of removable front and side curtains, facilitate access to the mainsail and the back of the boom, allow for mounting multiple solar panels, and be able to collect a significant amount of fresh rain water. Careful design will prevent water from entering the cockpit during rains while still allowing some ventilation. Ensure the edges won’t drip on the cockpit seats or instruments. Lightweight construction is a plus.

Dinghy davits: Some dinghy davits are incorporated into an arch or tubular support for the cockpit top. These need to be very strongly constructed because the dinghy usually lives there at sea. It should allow hoisting of the dinghy well above the water to help prevent theft and wave slap.

Saloon windows and doors: Extra strength and careful design are required to prevent large breaking waves from flooding the boat and easy entry by an intruder. Thick polycarbonate/Lexan or safety glass is best; acrylic/Plexiglas should not be used. Inspect the window mountings and door hardware carefully for adequate strength and watertightness. Consider main cabin window designs that limit heat entry from the midday sun.

Ventilation: Multiple opening hatches and ports should ventilate every space, especially the saloon, galley, sleeping quarters and heads. We have 14 hatches, six ports and two escape hatches — all opening. Escape hatches provide excellent ventilation, should be large enough for you to pass through, and should be located at least 18 inches above the waterline to prevent flooding while open at anchor. All should be of quality manufacture with tight replaceable seals. Provisions to prevent intruder entry are a plus. Consider how well ventilated the cockpit is in light wind conditions.

Crash bulkheads: Modern catamarans have crash bulkheads located forward and aft in each hull to prevent collision flooding. They should be well sealed from adjacent spaces and have door lips well above the waterline. Obviously, these are not places for heavy gear. Installation of large holding tanks, which are usually empty at sea, can provide a double bottom in the bow.

There is plenty here to consider before purchasing a cruising catamaran. Many modern cats are built for the lucrative charter trade and have features that may not work well — like minimal fuel storage capacity — for full-time ocean cruising. Some of these can be corrected or improved, some cannot. There is much good information on the Internet, but be suspicious of dealer hype. Ask specific questions and request proof of anything that doesn’t seem right. Make a list of what to look for before going aboard a potential purchase.   Although most cruisers spend 90 percent of their time in port, due consideration should also be given to features that enhance safety and comfort at sea. Most catamarans are optimized for tropics cruising and are probably not the best choices for high-latitude voyaging.

There is no perfect catamaran with all the features you will want, so be prepared to compromise somewhat. Photos and more detail are available on our website below, under a slide presentation titled “ Evaluating Modern Catamarans .”

Dave McCampbell is a retired U.S. Navy diving and salvage officer with over 40 years’ cruising and eight sailboats’ worth of maintenance experience. He and his wife, Sherry, have recently cruised the eastern portion of Southeast Asia, including the Philippines, Raja Ampat, Papua New Guinea and the Solomons. Earlier, they spent eight years slowly crossing the Pacific. After 19 years aboard their CSY 44 monohull, they bought a St. Francis 44 Mk II catamaran in 2015.

By Ocean Navigator

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CATAMARAN DESIGN and BRIDEDECK CLEARANCE

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Open for discussions and opinions (1) Interested in comments from Catamaran owners re Bridge deck clearance. I have heard reports about low bridge deck clearance causes Slamming and pounding of significant proportions when sailing to windward. Comments please. (2) Some designs have .500m clearance others .700m and I notice the latest designs on some are rising to .950m and 1.2m bridge deck clearance. Comments please. (3) I have noticed quite a few catamarans stay in port while Monohulls make passage to their next port. When asked why they are staying in port I,m told waiting for for less wind and a better wind angle. Supposedly this has something to do with Slamming and pounding? Comments please. ( 4) Galley preference. Main bridge deck or hull. As a interested cook and have cooked on numerous vessels I ponder the merits in having the galley within the bridge deck. Re heat transfer- Condensation- Moisture- the heat generated from the galley causing condensation on the ceiling, moisture gathering in drapes, upholstery plus smells and vapours, books in library pages being affected and absorbing the moisture. As usually with most modern designs the chart table and electricall main board and electronics are also positioned in main saloon - bridge deck, I wonder the wisdom re this. I would have thought the galley in the hull would be preferable with higher head room - hatches and extractions fans and more ventilation - thus removal and moisture control would be more efficient, plus providing a larger lounge area in the main saloon. After all the kitchen in most homes is not in the lounge. Plus normally in the tropics if one does not have air conditioning one gathers with chilled drinks in the cockpit area with sea breezes and a view and possibly to be a nosey parker while the cook cooks. Comments please. Below are some hyperlinks to a new design with increased bridge deck clearance. How ever I,m would have thought for offshore passage and in moderate to heavy seas a clearance around about 1.6m to 1.8m would be needed to avoid constant bridge deck slamming when going to windward or even slightly cracked sheets. Comments please. http://www.schionningdesigns.com.au/1700c http://www.schionningdesigns.com.au/gforce-1800 http://www.schionningdesigns.com.au/1200 Thanks in anticipation. http://homepages.ihug.co.nz/~philclarke/flag%20ETIQUETTE.htm -------------------------------------------------------------------------------- __________________ "Let the sun shine, let the rain cease, let the lakes and rivers run dry so 2012AD, 2013AD & 2014AD are good vintage years and gold, elite gold medal winning years for N.Z.wines" Now!! :chaser :chaser  

Why wouldn't bridgedeck clearance be a function of size?  

It's not a function of size, just look at some of the condomarans with 40' loa and 10 inches of clearance. I seem to recall reading somewhere that the absolute minimum bridgedeck clearance you want is 19", from the lowest point of the bridgedeck to the water. This includes any Nacelle (spelling?) hanging down from the bridgedeck. If you really want to understand this issue go to boatdesign.net and do a forum search, there is lots and lots of data, much of it from NA's and designers (richard woods posts there frequently) and you will get a fuller understanding of the issue.  

peterchech said: ...If you really want to understand this issue go to boatdesign.net and do a forum search, there is lots and lots of data, much of it from NA's and designers (richard woods posts there frequently) and you will get a fuller understanding of the issue. Click to expand...

I don't know enough about the bridge deck issue to comment on specific heights but insufficient height is a major problem from what I do know. Regarding the interior, I'd favour a downstairs galley. My biggest complaint about catamaran layouts is the restricted seating space in the saloon where much space is taken up by the galley and/or nav station. Must say I do like the layout of the Schoening 1320 though I know nothing about the boat itself. The 1700 is for my money absurdly large, but then I only think about space for a couple plus very occasional guests. The way I figure the galley is this. Down below gets it out of the way with one major drawback being heat in warmer climes. For me that is negated by the fact that in summer we always cook outside and with a cats cockpit even preparation outside is simple. Others might say that the galley in the saloon allows more interaction twixt the cook and the crew. Fair enough I guess but I still don't think that outweighs the other issues.  

tdw said: I don't know enough about the bridge deck issue to comment on specific heights but insufficient height is a major problem from what I do know. {Thanks} Regarding the interior, I'd favour a downstairs galley. My biggest complaint about catamaran layouts is the restricted seating space in the saloon where much space is taken up by the galley and/or nav station. [Agree my thoughts exactly] Must say I do like the layout of the Schoening 1320 though I know nothing about the boat itself. The 1700 is for my money absurdly large ,[ I think you need it if your doing offshore passages and have extra crew to help with watches so one does not get tired and irritable, and depending on your age.] but then I only think about space for a couple plus very occasional guests. The way I figure the galley is this. Down below gets it out of the way with one major drawback being heat in warmer climes. For me that is negated by the fact that in summer we always cook outside and with a cats cockpit even preparation outside is simple. [ Most boats these days have a BBQ,s hanging from the stantions or pushpit.] Others might say that the galley in the saloon allows more interaction twixt the cook and the crew. Fair enough I guess but I still don't think that outweighs the other issues.[/QUOTE ][ Good point agree.] Oceancruiser. Click to expand...

Most any catamaran will pound in certain sea states. If you're looking to eliminate pounding, buy a monomoran. I dont have rules of measurement that I can help you with but common sense should prevail. If the bridge deck clearance looks low, its going to pound more that one that does not look low. Galley down works for us. Its open and inclusive of folks working in the galley with those living in the saloon. When I was chartering catamarans for vacation sailing, I prefered galley up. Living aboard, galley up is a deal breaker. I dont want to cook in my living room. We comfortably seat 6. 8 is a push, but doable for dinner.  

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My comments about Bridge-deck clearance comes from the lips of designer comments I have read. They also come from a Cat sailor who owns a Catana 381 that has 2' 6" clearance and it does not slam, I know because I sail it like the Tornado Olimpis Cat I used to race. I am just about to Launch my Website which tell you what Cat NOT TO BUY, depending on your requirements of course, if you want a Condo, have one, if you want to sail sideways have Skegs, if you like Hobby Horsing or slow Cats there are thousands out there, mostly from the Production boat department. Watch out over the next few months when I launch my Web site, type in Catamaran and you will find me. As for the topic in question: there are 6 main things you need in a good Cat design and one of them is NOT low bridge-deck clearance. Most Cats have none of the 6 requirements, they either have Fat hulls, Skegs, reduced Sail area, bad Bridge-deck clearance, too heavy and wide open slot and they all sail like floating Homes. I have 200 Cat listed on my database all with designer calculations saying which one is capable of sailing well, assuming 'well' is whats wanted. I'm looking at 6 Cats I might buy in the 45-48' range, they must have at least 4 to 5 of the 6 design requirements listed above, if they don't I move on. I have been told my requirement is very high and most Cats don't have what I want, that is true. I can find only 10 Cats that come into my top ten for sailing ability and the all have High Bridge-deck clearance. I sail at 35deg to wind beating of Monohulls who try to get near me, to windward of course, I sail higher than them. I don't want to give too much away in Loo of my Web site Launch. There is a small fee but it's worth it. Regards Barry Parkinson Ex Tornado helm and Catana 381 owner.  

Quote: I can find only 10 Cats that come into my top ten for sailing ability and the all have High Bridge-deck clearance Interested to see your top 10 sailling ability Cats and the hights of there respective bridge deck clearance. I also notice from the Catana Web site there new design has reversed bows and they have increased there bridge deck clearance. Not to dis-similar from the design above hyperlinked. Interesting !! Be interesting to see how yourwebsite goes-- Fee/ pay by credit card. I don't think so  

I am interested to see those 6 requirements as well. The problem with catamarans is that in order to retain the excellent performance that multis are capable of, the catamaran has to have certain features such as narrow hulls, low windage (ie minimal bridgedeck), daggerboards, etc. These very features mean that to have comfortable accomodations the cat has to be very big. Otherwise something has to give. And once you get big, most boat owners get priced out. You need bucku bucks to buy a 50' catamaran, and even more to find a place to keep it. So, as with everything in life, compromise is required. Some compromise better than others, but since the charter market seems to drive catamaran sales, the accomodations are favored over the performance/safety in most commercial designs. I personally am a sailor, not a on the hook cruiser or live aboard, so even when cruising I can't tolerate a poorly sailing vessel and would never get a condo maran. But others, particularly those who charter, may have different priorities. For this reason I think a trimaran is the way to go if sailing performance is what you want. Most trimarans are not built for anything but true sailing ability. Those who buy a tri generally want to go fast and have fun. The arms fold up so you can find a spot in a marina. The accomodations are more like a smaller loa monohull, and way less comfortable than a cat, but that is the kind of compromise I am willing to make personally. If you want that standing headroom bridgedeck, the compromise is high windage and poor bridgedeck clearance, at least until you get to a really big cat IMHO. BTW, "The Cruising Multihull", by Chris White, is an excellent book on this subject, and is available as a pdf download or else used on amazon for $10 when I bought it. It's a wonderful book and you should def read it before buying any multihull, it addresses all these issues and compromises from the standpoint of a designer and full time cruiser. Great read too, not overly technical and very enjoyable.  

peterchech said: ... For this reason I think a trimaran is the way to go if sailing performance is what you want. Most trimarans are not built for anything but true sailing ability. Those who buy a tri generally want to go fast and have fun. The arms fold up so you can find a spot in a marina. The accomodations are more like a smaller loa monohull, and way less comfortable than a cat, but that is the kind of compromise I am willing to make personally. If you want that standing headroom bridgedeck, the compromise is high windage and poor bridgedeck clearance, at least until you get to a really big cat IMHO. .... Click to expand...

Hi petercheck, I have read your thread and I bet you are interested in my top ten Cats and the 6 requirements for quick Cat sailing, thats why I am launching My 'What Cat not to buy and why' Lots of Cat buyers are sold up the river by Brokers who say 'have a nice day' but don't mean it. I got fed up listening to the garbage Brokers talk over the past 5 years, and that is the main reason for Launching my Website. The other one is because a Great Cat in the West Palm Beach in the Cracker Boy Yard, has been butchered by the Loving owners, I wanted to but it until I put it through my Spreadsheet to get a 'Bruce number' (Power to weight ratio) and it sucked. I asked the Architect what was in the original design and found they had cut the Dagger-boards in half and poss the rudders as well, loaded the weight up from 10 Ton to 12 Ton, reduced the sail area and generally messed up a very good Cat that cannot sail well anymore. I wanted to expose people and Brokers like this to the budding Cat sailor who has a lot to learn about Cats and end up buying things that float, thats why it is called a boat, but it does not sail well because the production Cats do not have any of the 6 requirements I talk of. I could talk for a week on Cat design but this is not the place to do it. All I want to do is give potential Cat buyers somewhere they can go to ask questions about potential Cat purchases they might make, before they make a mistake, like so many Cat owners who are disappointed with what they bought, for one reason or another. I know the answers, with 200 Cats on my database I should do, and soon I will be able to let the Cat buying public know what Catamaran/Multihull not to buy. Give me 2 weeks and I should be Online with my Website but, there is a small fee, but you said you did not thinks so, I take it you don't thing buyers will pay $50 to find out what I know, we will see. It's been great talking, no doubt we will do more. I am looking forward to helping cat buyers choose the correct boat before they buy. Best regards Barry Parkinson  

Bazcatana said: Hi petercheck, I have read your thread and I bet you are interested in my top ten Cats and the 6 requirements for quick Cat sailing, thats why I am launching My 'What Cat not to buy and why I asked the Architect what was in the original design and found they had cut the Dagger-boards in half and poss the rudders as well, loaded the weight up from 10 Ton to 12 Ton, reduced the sail area and generally messed up a very good Cat that cannot sail well anymore. I wanted to expose people and Brokers like this to the budding Cat sailor who has a lot to learn about Cats and end up buying things that float, thats why it is called a boat, but it does not sail well because the production Cats do not have any of the 6 requirements I talk of. . All I want to do is give potential Cat buyers somewhere they can go to ask questions about potential Cat purchases they might make, before they make a mistake, like so many Cat owners who are disappointed with what they bought, for one reason or another. Give me 2 weeks and I should be Online with my Website but, there is a small fee, but you said you did not thinks so , [ No that was me] I take it you don't thing buyers will pay $50 to find out what I know, we will see. I am looking forward to helping cat buyers choose the correct boat before they buy. Best regards Barry Parkinson Click to expand...

giving someone $50 for the same 2 cents you can find elsewhere on the internet seems a tad unrealistic to me, but I wish you good luck none the less!  

Hi again petercheck, CREDIBILITY was my first requirement 5 years ago when this all got going. I extracted the design mathematics for my 'Power to Weight Ratio' spreadsheet (Bruce number) from the design pages of a top quality Catamaran designer in Australia, there on the web for all to see. I built my Spreadsheet using this information that they use when designing Cats/Multihulls to establish what works and what does not. I am not preaching MY thoughts and feelings, I am preaching THEIR design knowledge, not mine. I am not presumptuous enough to think anybody is interested in my views, that is just like another Blogger saying what he thinks, and whats the value in that, it's not credible. Your right, nobody knows who I am, I could be any old Blogger voicing his opinion, it will take time for my reputation to filter through but, I can tell you it stops the Brokers dead in their tracks, when you ask the questions I ask and request the data I require for my 'Bruce number' calculation. The method of payment I will use is via PayPal which I am told is secure, I don't see the Credit Card details, only the payment. Then I send my report to the potential Catamaran/Multihull buyer, telling them what NOT TO BUY if there is something that shows up in my calculations, and you can't get that for 2 cents on the Web anywhere. I have met hundreds of new Cat owners who are disappointed with their purchase. They think all Cats are fast, it's a misconception that many fall into, blinded by Broker and Press garbage they talk and publish. Try me out for FREE, send me some details of a Catamaran you would like to buy, send it to my [email protected] Email and I will send you a Form to fill in. Return that to me and I will tell you what I think. Don't play around, try and be serious, I am trying to HELP buyers choose a Cat that they will be happy with, I'm not selling anything, just helping buyers find the ideal Multihull. Regards Barry Parkinson  

Bazcatana said: I have met hundreds of new Cat owners who are disappointed with their purchase. They think all Cats are fast, it's a misconception that many fall into, blinded by Broker and Press garbage they talk and publish. Try me out for FREE, send me some details of a Catamaran you would like to buy. Regards Barry Parkinson Click to expand...

Try me out for FREE, send me some details of a Catamaran you would like to buy, send it to my [email protected] Email and I will send you a Form to fill in. Return that to me and I will tell you what I think. Don't play around, try and be serious, I am trying to HELP buyers choose a Cat that they will be happy with, I'm not selling anything, just helping buyers find the ideal Multihull. Regards Barry Parkinson[/QUOTE] You will have 11 after viewing this Cat Young Yacht Design Be interested to know if it passes you scrutiny.  

Where is a site to get complete specs on various cat designs ?  

Where is a site to get complete specs on various cat designs ? Click to expand...

Thanks.  

I have paid a great deal of attention to the cats cruising the Antilles over the last 3 years. 90% of them are just floating condos, without the ability to go to windward or down wind well, unless the have down wind sails specifically built. Few have 1/2 enough clearance under the "bridge deck" to be comfortable in a 3' chop, let alone an average tradewind day down here. Most are rigged so you can't let the main out far enough to comfortably sail on a broad reach, and almost every single one we see sailing interisland has at least one engine on, even on a breezy tradewind day. Most have a very sharp, jerky motion which must be horribly uncomfortable under way or in a rolly anchorage. There are a few designs which have dagger boards and enough freeboard to quite possibly sail decently, but they still don't seem to have the speed to make up for the difference in the pointing ability of a good monohull. As for trimarans, there are good ones and bad ones, like any other type of boat. If we exclude racing tris and concentrate on cruising tris, none have the speed or agility to sail safely through pirate filled waters (pirates usually operate on calmer days, certainly not in the gale force winds it would take to get away). Unless you have several very, very experienced crew on board a tri at sea, most cruisers would not be able to maintain the 16 to 25 knots it would take to out run a storm. It certainly would not be prudent to put her on autopilot or a windvane at those speeds, IMO. I do think a well designed cruising tri is a far superior sailing vessel to any cat out there, and a much more stable platform from which to set sails. I sailed a Brown Searunner 37' from Pago Pago to the VI, crossing 1/2 the Pacific, the Indian Ocean, the Red Sea, the Med and Atlantic. I sailed her out of a hurricane in the Indian Ocean, 1200 miles hard to weather up the Red Sea and through many a gale without any problems. Inside the reefs of New Caledonia, I had her up to nearly 25 knots, but that was flat water in perfect conditions. At sea, I would never let the mindless machine (the windvane) sail the boat above 10 knots, period. Best of all, I could sail in light air, when every monohull and cat was motoring, usually making around 5 knots. It was the most wonderful cruising boat I've ever sailed, but they must be kept very, very light. Pretty much bare bones sailing with few mod cons, which is why I've gone back to a monohull in my old age. If you want to SAIL, then you are better off choosing a monohull or trimaran. If you are just looking to move to a mobile house on the water, then the majority of the cats out there are the perfect choice. Every boat is a compromise.  

Strange. I sailed on a Chris White 56 ft tri ocean going . No problems reaching 12 knts boat speed 12 knts slight cracked sheets, wind speed. 18 knts, boat speed at 19 knts wind speed. At 12 knots forward cabin berths uncomfortable to sleep and at 16 knts had to be strapped on. Although no lee clothes or straps where standard equipment. I rightly or wrongly put this due to the chine design main hull near waterline bow to mid ships. We either slowed the boat or move aft. Had a turbo charge engine and at cruising revs 66 2/3 12 knts at full revs 16 knts. At 6 knts wind speed achieved 6 knts boat speed. Most watches where single person watches and usually on auto pilot. So I guess if people are going to sail through pirate territory a chris whit tri should give some self confidence and added safety as a worth while consideration. Thanks for your comments.  

Well, there's the 'rub', so to speak. Unless you've bought yourself a new America's Cup class catamaran, a catamaran sailor isn't going to be arguing his boat goes to weather better than a monohull. But the question is ... is that how you define the boat you want own? How high she points? That doesn't even make my top ten list. Finding a boat that my lady can't wait to sail on rates a lot higher, as without her, I'm not going anywhere. Comfort while cruising is high on he list as I just can't picture her standing on a bulkhead for days at a time. And whether you sail one hull or two, sailing (relatively)small FRP boats is all about picking a weather window. I'm at that stage of life where I know how to pick my battles... and boats ...like life ... are all about compromises, right?  

With a cat it's not so much how high you can point but VMG. The cat may sail 5 or so degrees more of the wind but will reach their destination quicker. True, the trend nowadays is for the condo cat, but there are still some performance oriented cats still around. It's been my experience that we usually sail past the monos that are motor sailing. The cats must have some appeal as a lot of the experienced mono hullers are transitioning toward cats. Not everybody's cup of tea though.  

Thanks, but I'm really looking for owners with Cats to confirm slamming re their owned vessels and the designs bridge deck numbers and owners that have sailed to windward with 36 knts on the nose wind with no slamming and the bridge deck clearance numbers. On a long passages there is always on the wind part sailing even to enter port on most occasions. VMG is important unless you want to change your port on entry. I have known mono hull sailors vessels to do so to the protests of the crew. His argument he did not like to sail on the wind. The crew argued "you guaranteed the place as a stop over and we accepted your vessel as crew and are paying $30 per day other wise we would have chosen another vessel". As for sailing not so high I would respectfully disagree. Some years ago a racing cat design By David barker and the fastest cat around at the time, Auckland to Suva just under three days 1300 nms did the numbers. Had a girl friend at AMP computer room feed all the points on sail from hard on the wind to reaching to determine the increased speed he would have to achieve to be ahead. The computer print he stated stretched the entire width of Sydney harbour. He spent days trying and never achieved any of the speeds that where required according to the computer results. Thanks for you expanding comments. Kind Wishes. http://homepages.ihug.co.nz/~philclarke/SAILING%20MECCA.htm  

Yes, someone is going to beat into that. Well, it was 30kt, not 36. It was a Gulf crossing/delivery, and we didn't have the luxury of heading off. Boat is a 1992 Catana 40S. In this vid, we are motorsailing. By this time the wind had cocked slightly east of exactly, directly, in front of us, so we did hang some laundry, but for probably 8 or more hours before the wind had been directly on the nose (frontal passage) and we just doused and engined into it. Despite the high bridgedeck, and believe me I don't load my boats down, she did some banging, although I believe had the wavelengths been longer, banging might have been less. The Gulf of Mexico has a surprisingly short wave pattern, short and steep. Apparently TropicCat is quite lucky to be able to make the choices he apparently does. As for the rest of us, sometimes you just gotta get there.  

Multihullgirl said: Yes, someone is going to beat into that. Well, it was 30kt, not 36. It was a Gulf crossing/delivery, and we didn't have the luxury of heading off. Boat is a 1992 Catana 40S. In this vid, we are motorsailing. By this time the wind had cocked slightly east of exactly, directly, in front of us, so we did hang some laundry, but for probably 8 or more hours before the wind had been directly on the nose (frontal passage) and we just doused and engined into it. Despite the high bridgedeck, and believe me I don't load my boats down, she did some banging, although I believe had the wavelengths been longer, banging might have been less. The Gulf of Mexico has a surprisingly short wave pattern, short and steep. Apparently TropicCat is quite lucky to be able to make the choices he apparently does. As for the rest of us, sometimes you just gotta get there. Click to expand...

If you don't have speed you have nothing let alone safety. Firmly believe boats should have enough speed to sail around a cyclone or a storm or get to port before the storm arrives at your sailing course / path. NOT ONE FOR WAITING FOR 42 DAYS OR MORE FOR A WINDOW TO SUIT A SLOW CROSSING. berth age fees for multihull vessels are far to expensive for long port stays and one seems to spend the time when waiting for a weather window partying, which is also expensive during long stays at ports. WITH RESPECT AGAIN, WHEN I'm IN A HURRY I catch a commercial airline jet.  

Sailed a 44' aluminium cat to India from Thailand. Sometimes you couldn't put your coffee cup on the table for the slamming. Got real tiring. Condensation was bad and ventilation at sea minimal or wet. Great on the hook for entertaining and lots of storage space on board as long as you don't put anything in it. Saw another cat (sleek Italian job) with a bloody big gen set in one hull and a washer/dryer/freezer in the other. Neither of these vessels sailed worth a damm. And didn't even have the classic good looks and comfort of my homebuilt gaffer.  

piclarke said: After all the kitchen in most homes is not in the lounge. Click to expand...

Thanks for your comments. I do not like cleaning and the kitchen is my domain also for hygiene reasons, so parting at the kitchen is a no no. Use the Cockpit BBQ when parting. I have and always try to party at the cockpit area as the guests quite correctly are not asked to clean the mess they leave when parting. Accordingly the bucket and lanyard or pressure hose does the trick especially when some can't hold their drink and vomit. Best regards.  

I've said before: I'd just as soon not have the burny bits in the floaty bits. Bridgedeck galley for me.  

I don't know how high my bridge is, and to be honest, it really doesn't matter. I may stand corrected here, but I'd bet that there is no such thing as a cat which doesn't suffer some slamming, if the conditions are right for her to slam. Of course, the lower the bridge, the more often that slamming will occur. It's fairly obvious which cats are low and which aren't, just by looking. A few cm one way or the other ain't going to tell any tales. BTW, the answers you seek are already discussed ad nauseum online, and there are plenty of books on the subject. If you find it painful to Google, I find it painful to repeat freely available information.  

quote=Multihullgirl;2300938]I don't know how high my bridge is, and to be honest, it really doesn't matter. I may stand corrected here, but I'd bet that there is no such thing as a cat which doesn't suffer some slamming, if the conditions are right for her to slam. Of course, the lower the bridge, the more often that slamming will occur. It's fairly obvious which cats are low and which aren't, just by looking. A few cm one way or the other ain't going to tell any tales. BTW, the answers you seek are already discussed ad nauseum online, and there are plenty of books on the subject. If you find it painful to Google, I find it painful to repeat freely available information.[/quote] Thanks for your comments. A proven and now accepted as the best and fastest cruising catamaran designer states his Catamarans do not slam. His designs have bridge decks clearance between .950 and 1.2 meters and he states bridge deck clearance does matter and I attend to agree. The numbers have not been discussed ad nausea online as can been seen from the posts so far. Even your posts do not quote the numbers. Been to the manufacturer Catana website which does not quote a 40s model and the length vessels that are their models, custom built vessels specifications bridge deck clearance are not mentioned on all the designs. With respect I'm actually trying to find a Catamaran owner with bridge deck clearance .950 or more that can state / verify his vessel does not slam going to windward sailing or motoring with heavy seas or confused seas / or heavy confused harbour waters. Is this not what forums are for. Trying to establish what the manufactures claim to be correct or incorrect. http://homepages.ihug.co.nz/~philclarke/americascupstats.html  

piclarke said: With respect I'm actually trying to find a Catamaran owner with bridge deck clearance .950 or more that can state / verify his vessel does not slam going to windward sailing or motoring with heavy seas or confused seas / or heavy confused harbour waters. Is this not what forums are for. Trying to establish what the manufactures claim to be correct or incorrect.... Click to expand...

Gavin le Sueur, MULTIHULL SEAMANSHIP Rudy Choy, CATAMARANS OFFSHORE Chris White, THE CRUISING MULTIHULL Derek Harvey, MULTIHULLS FOR CRUISING AND RACING Rob James, MULTIHULLS OFFSHORE that should get you started. BTW, manufacturers don't really lie outright, but they stretch the hell out of the truth... I reread my post. I'll clarify my point: when I said 'it doesn't matter,' I mean, the numbers don't matter. I can see the difference between a high and a low bridge cat. That isn't the only consideration for a seagoing cat. I believe there is no such thing as a cat with a high enough bridge that will never, ever slam. I believe it is best to get a high-bridgedeck cat to avoid slamming, but I find it hard to believe that there is a cat that will not find itself doing some slamming at some point. I went to the Miami show and looked at the new cat designs, and with one exception, I'd be damned if I'd go to sea in them, frankly. And the bridgedecks weren't the worst problem these boats had IMO.  

QUOTE and with one exception, I'd be damned if I'd go to sea in them, Care to name the design and provide a hyperlink to the designer. Interested as to what you would choose to sail across oceans. Plus other members would also be interested I presume. I look forward to your reply. Worldwide Best Yachting surf beach harbour entrances and ocean sea conditions with Web Cams reports and weather swell reports marine data resource links site business accommdation directory guide lists base including new zealand australia south pacif  

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Top 6 Characteristics of a Good Catamaran

What Makes a Good Catamaran?

As we (Stephen and Estelle) self-isolate during this pandemic aboard Zuri, our Bali 5.4, we thought we would share some insights about important features you should think about when buying a catamaran. We started out with 5 then at the end, Stephen threw in another 3. What are your thoughts? What are important features on a catamaran. Let us know below in the comment section.

Like all marine vessels, certain characteristics make some catamarans better than others. You will not find a perfect catamaran because no boat is perfect. Compromise is always required. But with forethought about how you will utilize your multihull, and matching your requirements to high quality design, you can get pretty close to your “dream” catamaran.

Crucial attributes to consider for a cruising catamaran are:

• Weight-carrying ability
• Bridge deck clearance
• Structural integrity and seaworthiness
• Windward ability
• Deck surface design
• Ease of handling

We will explore each of these catamaran characteristics, and how they affect performance, comfort, and, ultimately, safety.

Early catamaran designs were heavy by today’s standards. The multihulls were designed with a narrow beam, high freeboard, and inefficient underwater design. They were prone to hobby horsing and pitching. Today, with the technological advancements of lighter, stronger composite materials, catamarans performance has greatly improved.

In the last 20 years or so, boat builders have painstakingly studied and resolved the issues affecting catamarans, effectively increasing their seaworthiness by leaps and bounds. Constant reform and transformation of even the basic tenets of catamaran design continue today as is evident in the radical catamaran designs in the 2013 America’s Cup Challenge. (The foiling Gunboat G4 designs spring to mind). In fact, many of the problems of the older multihull designs have been eliminated altogether.

The new generation of cruising catamarans offers exciting, fun sailing vessels with great livability, space, comfort, and safety. This was made possible, in no small part, by the early multihull pioneers.

Catamaran Stability & Weight-Carrying Ability

WEIGHT: Unlike the monohull design that can carry weight without much loss of performance, an overloaded catamaran rapidly loses performance and, eventually, safety. In order to counter this, multihull manufacturers are continually looking for ways to reduce construction weight to increase the potential payload capacity while retaining optimal performance.To select a light catamaran, look for hulls with cored construction and interiors built with lightweight materials.  Lighter construction enables catamarans to carry more weight and perform faster, so this characteristic is very important when selecting a cruising catamaran.

Monohulls can heel and spill wind when the sails are overpowered. But a catamaran’s only available response to pressure of a wind gust is to accelerate. So the boat has to be very strong to hold together. Cored construction makes the catamaran strong and very stiff. Stiffness gives a catamaran good performance.

Consider that the catamaran’s hulls are actually two boats joined together by a bridge deck. These “boats” are constantly fighting each other and trying to go in their own direction. The boat structure must be strong enough to counter this and, at the same time, deal with the downforce of the mast in the center of the bridge deck. The catamaran performs an amazing feat contending with all the opposing forces inherent in the multihull design. For that reason, it is critical to ensure the design and manufacturer are reputable with a track record to demonstrate structural integrity.

STABILITY: Unlike monohulls that rely on a heavy lead keel to keep it upright, a catamaran relies on the beam of the boat and the buoyancy of the hulls for stability. Typically cruising catamarans will have a beam to length ratio of roughly 50%. So a 45-ft long catamaran will be about 22-ft wide, providing a very stable platform. Good stability in a catamaran is when the righting forces and healing forces are in balance. So if the righting moment is greater than the capsizing moment, the boat stays upright. When the capsizing moment becomes bigger than the righting moment due to an increase in wind, the boat starts to capsize. <

This diagram and article by James Wharram, king of “self-build” catamarans, offer valuable insight into catamaran stability. Also, read this article by Shuttleworth “ Design Considerations for Seaworthiness “.

Catamaran Bridge Deck Clearance

Bridge deck clearance is a key factor in predicting the slamming level of a catamaran design. A higher clearance produces less slamming. My rule of thumb is; 4% of the overall length is low, 5% is acceptable, and 6% is good.

When it comes to slamming, another important factor is weight. If the boat is heavy due to construction or payload, it will tend to go into a wave. This slams the chest of the boat into the wave. A lighter boat with more buoyancy will rise on the wave reducing slamming substantially. “ The Space Between ” by Sackville Currie, explains in detail the different options, problems, and compromises.

Windward Ability: Catamaran Keels vs. Dagger Boards

Catamarans with dagger boards are able to point much better than catamarans with keels. The claim is that a catamaran with dagger boards is safer because if the boards are up and the boat gets sideways on a wave, it will skid down the wave sideways. Dagger board proponents believe a keel trips the boat as it tries to navigate down the side of a wave causing capsize.

I can only speak from personal experience. I was caught sideways on a 20-foot wave a few days out of Cape Town on a 40ft catamaran with keels. The boat was hit by successive three waves before we could get it back on track. The boat skidded down the waves and there was no capsize, but it took some nifty maneuvering at the helm. My personal belief is that both types are safe and acceptable provided they are operated correctly.

Catamaran Deck Surfaces

Cockpit to Mast

Older designs often have decks with two levels from the coach roof windows to the gunnels which form a side deck with a trip hazard. Most modern catamaran deck designs are now one flat surface being wide enough to walk unhindered from the cockpit to the mast.

The cockpit and the saloon should be on one level with no step down into the saloon, if possible. Modern designs have achieved this and it really makes a big difference for ease of movement and safety while at sea.

The steps on the stern should be wide and easy to climb with a reasonable angle. If the steps are too steep or narrow, they become a hazard and lose space for recreation. The stern should be easily accessible from the dinghy.

Ease of Handling: Catamaran Deck Layout

• Both jib sheets
• The sheet from the opposite side of the boat should be run through a turn block and across the coach roof through a clutch to the helm
• Jib furling line
• Single line reefing lines
• Main halyard
• Traveler control lines.

Visibility from the helm is also very important. All round visibility while underway, maneuvering, or docking is key to safety of your boat and others’ property and life. When standing at the helm, you should be able to see both bows or, at the very least, the pulpits. The center of the crossbeam where the anchor is handled from should be visible as well as both sterns for when you dock “stern to”. If all these stations are not visible while standing at the helm where the engine controls are, you may encounter problems because of blind spots.

Catamaran Characteristics Conclusion

Modern catamaran designs are much more advanced than the early models that were slower, heavier, and underpowered. Problems like hobby horsing, burying the bows, and underpowered rigs have been largely eliminated.

Even though composite construction technology gives a huge advantage in lighter materials and sleeker designs, no one design element or piece of high tech gear should dominate the vessel to the detriment of others. With some compromise, a good naval architect can design a vessel pleasing to most people and the result can be very exciting, safe, and seaworthy.

Top Tip: Use a Broker at No Cost

Which compromises should you make when selecting your catamaran? It all depends on how you will use her. Catamaran Guru helps new and veteran multihull owners select the right boat for their dreams at no cost! The yacht seller pays broker commissions so our advice from gleaned from thousands of boat-buying transactions is free to you. We will help you find right boat, the right program, or the right situation. If you want to explore more on your own, visit our buying a catamaran section.

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Bridge Deck Slap- Gemini Catamaran

Gemini sailing catamarans of Yacht A Fun’s 1997 vintage were designed such that small wave ripples are caught in the square shoulders of the inner hull transition.  When at sea, the small sounds are masked somewhat by the boom sound of the bridge deck being pounded by full sized waves and swell.

On a mooring, or at anchor, small waves reach the hull shoulder’s combination of bow to stern slope having 90 degree horizontal profile- and creates loud popping sounds as the wavelet ripples catch air pockets which explode with “plop, plop, plop” voices.  Some Gemini catamaran owners refer to it as “wave slap”.

Blue Marker helped outline the area before taping up the guide line

One CAN get used to the sound- kinda like living next to an airport!  Diann and I swore we’d do an up fit modification similar to the one effected by Jim Faughn on his Gemini named Freedom.  Thanks to Jim’s emailed coaching, our up fit is under way.

New epoxy doesn’t bond onto gelcoat with lasting results.  Therefore one has to grind / sand the gelcoat down to the underlying fiberglass.  Sounds simple doesn’t it.

Our up fit affects only six lineal feet of added 45 degree filler foam and new epoxy / fiberglass.  How long did it take me to sand out  1 ½ inch  ribbons (which totaled about 26 lineal feet) ? Try 12 hours while wearing a Tyvek suit, head sock, goggles, and respirator mask.

The Rockwell vibrating mult-tool’s triangular “hook and loop” head didn’t hold up to the task.  So, off to Lowes we went to acquire a cheap pointy ended Black & Decker sander.  The B&D sander held up- though I used over two dozen sanding pads!

Some surfboards are custom made with polystyrene.  We chose the denser version called  blue board.  Each board, from that 4 by 8 panel, had to be successively custom fitted to the hull shape.  To work through the process we re-purposed fifty drywall twist-function anchors as screws.

Once boards one and two were temporarily laminated via the “screws” we could hold them in place to mark board #3- and so forth thru six ½ inch foam board/strips.

Once comfortable with the laminated fit, the screws were removed, Gorilla glue added to areas of foam which had been sand paper scuffed, and the screws re-placed as guides and pressure points for the glue.

When both sets of slap stopper foam had been glued, we put small sections of plywood on top to press the glue joints as firmly as we could- and let it sit all night.

One inch by 2 inch furring strips were used to support the sections while being attached using 100% silicon adhesive.  The adhesive’s purpose was to keep the foam in place:

while being dressed down to the final shape;

while being “faired” with West System epoxy 105 resin, 206 hardener, and 410 filler; and

while having three layers of fiberglass cloth laminated (over the faired foam) onto the hull’s

fiberglass ribbons.

Once the fiberglass / epoxy has cured, gelcoat will be applied; and bottom painting can be completed.

Conceiving a boat improvement project, “priceless”.  Executing the project- very time consuming!

The story / blog of Yacht A Fun, a Gemini catamaran sailboat, traveling the ICW and east coast with insights to the extended cruising life. Bridge deck slap

I’m a recent new owner of Gemini hull #828 and I’m very interested in how effective your bridgedeck slapping fix turned out. The slapping & pounding are very frustrating so I’m trying to find a fix to reduce these wave effects.

Mike Krattli Maple Valley, Wa.

Slap fix seems to be effective. More use in July should help confirm the results.

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Posted 2024-08-26 16:59

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Brix Marine Hammer Catamaran 3814 - $1,200,000 (Price Reduced!)

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Brix Marine 3814-CTC-Offshore-SWA 2023 Brix Marine Hammer Catamaran now available!

• Twin Mercury V12 600 HP
• Length 38' Beam 14'
• Self bailing aluminum decks
• BEACHCOMBER landing gear for foot traffic only
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• SS door retainer clip
• WARN DC800 industrial hoist, black 12V
• Hull beaching plates DECK ACCESSORIES
• Extended T-transom c/w hinged aluminum gate
• Hand rails fore & aft deck
• Roof access ladder c/w flat rungs
• (2) Side boarding doors (port & stbd)
• Folding SS gunnel step (port side)
• Gunnel trays aft deck (port & stbd)
• (1) Hull access hatch c/w gas strut & flush hinges & ladder
• (1) Generator access hatch c/w gas strut, flush hinges & ladder
• (2) Fish storage lockers insulated c/w gas struts, flush hinges & macerator for discharge
• (2) Battery lockers c/w hinged doors, vents & drainage ports
• Compression latch, 316 SS, locking
• (2) Fish cleaning stations c/w two drawers (black) & overboard gut chute (1 port & 1 stbd) Approx. 52" x 30"
• Top cambered toward overboard gut chute
• 360 degree fiddle w/ stepped down fiddle height at working edge
• Removable starboard cutting surface (black)
• Hidden magnetic knife keep on aft, inboard corner
• (5) Welded aluminum rod holders on aft edge
• Second station c/w hinged door & latch
• (2) Watertight 12" round liftout hatches in outboard well
• (8) 11" tie up cleats
• (1) 8" tie up cleat
• Anodes for cathodic protection
• Swim ladder - deploys from under T-transom & includes vertical hand rails
• Alaskan overhang roof extension
• (9) Aluminum rod holders (locations TBD)
• (4) Aluminum coat hooks under exterior overhang
• Sink c/w mixer faucet on the aft deck (port side)
• (2) Downrigger pads (locations per drawing wired for Scotty)
• Removable aluminum tow post c/w stowage bracket in the outboard well
• Install OFE 80 gallon X-tream bait tank includes; Through deck soft patches for water & electrical connections.
• Bolt on "Tank Stays" from manufacturer c/w helicoil deck fittings.
• Separate raw water supply pump w/ thru hull & strainer. Overflow raw water to side thru hull c/w ball valve. DC control panel for pumps & tank lights located at aft station.
• UMT ECO 600 roof mounted dingy davit c/w roof mounted
• AB Inflatable c/w Yamaha 15hp motor, tiller, prop - includes fuel tank, lifting sling, chock pads
• Lammina 10AL inflatable dinghy
• Yamaha 15hp outboard w/ prop
• Fuel tank - 6 gallon bow tank
• Universal Dinghy chocks
• SS ratchet straps x 10'
• Crab pot puller w/ 12v plug
• Electra-Dyne 12V pot puller (250lb max load)
• ED7500-10 XHD w/ SS disc (20:1) 290 FPM max
• SS Davit (removable) c/w gunnel grommet
• Open block, fairlead roller, rope deflector & hand control included CUSTOM EXTERIOR COVERS
• Custom aft station cover Stamoid Black c/w SS fasteners & PTFE thread.
• Custom Fly bridge helm station cover Stamoid Black c/w SS fasteners & PTFE thread.
• Custom Fly bridge helm chair cover, Stamoid Black c/w SS fasteners & PTFE thread
• Custom Fly bridge bench covers 1-port, 1-stbd, Stamoid Black c/w SS fasteners & PTFE thread. STARBOARD-WALK-AROUND CABIN
• BRIX Headliner: fully insulated with easy to clean white fiberglass & Black wood trim w/ black screws
• Overhead grab rails along centerline
• BRIX Walls: fully insulated with Black carbon fiber finish & Black wood trim w/ black screws For additional information contact Michael Guess at Stevens Marine -- 971-442-2678 Keywords: 2-stroke, 4-Stroke, Allied, Alumaweld, aluminum boat, Arima, bennington, Boulton, C-Dory, Columbia, Commander, crestliner, Customweld, deck boat, deckboat, Defiance, DriftBoat, Duckworth, E-Teh, Evinrude, extended transom, Fishing Boat, Fishing Boats, Flat Bottom, Four Stroke, Fourstroke, G3, Gregor, Harber Craft, Harbercraft, Hewes Craft, Hewescraft, Honda engine, Honda kicker, Honda outboard, Intruder, Jetcraft, Kicker motor, King Fisher, Kingfisher, Klamath, Lowe, Lund, Mercury, Mercruiser, Motion Marine, North River, Northriver, Northwest Boats, Northwest Jet, NorthwestJet, Ocean Pro, Offshore fishing, Offshore Bracket, OS, Osprey, Outboard, pontoon, Pro kicker, prokicker, Pro XS, Pro Steel, Pro-Steelheader, Raider, River Hawk, Riverhawk, River Wild, Riverwild, Rogue, Rogue Marine, RogueJet, Scout, Sea Runner, Sea Sport, Seahawk, Searunner, Sea Sport, SHO, Sled, Smoker Craft, Smokercraft, Sportsman, Striper, Striker, Stryker, sunchaser, SuperVee, Suzuki engine, Suzuki kicker, Suzuki outboard, Sylvan, T9.9, Talon, Thunder Jet, Thunderjet, tracker, Trophy, Used Boat, Used Boats. Verado, Weldcraft, Willie, Willie Boats, Wooldridge, Yamaha engine, Yamaha kicker, Yamaha outboard, DLR#4222, Stevens Marine, Milwaukie, OR

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> > View Poll Results: What should I do? Worth paying for a proper survey 0% Walk away 100.00% Just buy the damn boat and fix it up! 0% Voters: . You may not vote on this poll Please support our sponsors and let them know you heard about their products on Cruisers Forums. 16-05-2024, 02:25   a 1990s - first so please help! It has balsa cores above the waterline. Solid below. The outside decks all feel strong no sponges bits.BUT the bridge is spongey and lifting the carpet shows the below. See pictures. The has a crack at one point The guy selling the said it was solid no problems he insisted.::, but surely if it’s spongey and someone has drilled observation holes he knew he also insisted the bilges were dry but there’s an inch or so of in each. Obviously not unusual but is it worrying he said they were dry? It also seems very down in the aft section on the waterline. I know with these there’s a lot of foam below the aft bunks that can become waterlogged - so I’m thinking this could be the reason? How fatal is all of this? Is it worth a ? It’s a cheapish boat, so a will cost about 10% of selling . Please help!         16-05-2024, 02:31   Boat: BUILT!!! Roberts Mauritius 43ft . 16-05-2024, 04:44   Boat: Shuttleworth Advantage intrusion or at the very least . Little bit of confusion about foam under bunks, structural foam does not become waterlogged, are you referring to some sort of buoyancy foam? If it is a know design there should be an owners group who would be better placed to know where the faults might occur. Balsa is always bad news. 16-05-2024, 04:48   Boat: Cruising Catamaran 16-05-2024, 05:27   16-05-2024, 05:30   Boat: Shuttleworth Advantage We warmly welcome all members of the Iroquois Owners’Association to the Heavenly Twins & Cruising Association now that we have merged. We would like you to feel welcome and we hope you will participate in as many things as you can. 16-05-2024, 05:35   Boat: Shuttleworth Advantage 16-05-2024, 05:44   16-05-2024, 05:51   16-05-2024, 05:57   is delaminated does anyone know how much that would cost to fix? Not DIY-ing it. But getting it done professionally? Obviously very ballpark 16-05-2024, 05:58   intrusion or at the very least . Little bit of confusion about foam under bunks, structural foam does not become waterlogged, are you referring to some sort of buoyancy foam? If it is a know design there should be an owners group who would be better placed to know where the faults might occur. Balsa is always bad news. 16-05-2024, 06:07   Boat: Shuttleworth Advantage 16-05-2024, 06:10   16-05-2024, 06:13   Boat: Shuttleworth Advantage 16-05-2024, 07:22   Boat: Gulfstar 50 ketch you spend on a survey back using it's findings as justification for price adjustment. Unless the survey turns up so much that you decide to walk away, in which case it's well spent to avoid getting into more of a "project" than you want to. Professional are going to be shockingly expensive especially compared to a "cheap" boat. If you're going to own a boat, especially an older boat on a , plan on how to do things yourself. Most aren't technically difficult, just messy and time consuming. You can/should hire a professional to give you guidance and for anything structural, then do the grunt yourself. My guestimate for cutting out bridgedeck floor, digging out wet floor, re-foaming and building new floor with improved structure, up and painting the area would be in the $10k ballpark. Probably similar to dig out and replace wet foam in the stern areas. , , Thread Tools Rate This Thread : Posting Rules post new threads post replies post attachments edit your posts is are code is are are are Similar Threads Thread Thread Starter Forum Replies Last Post gansett Construction, Maintenance & Refit 37 02-07-2020 23:56 tallboy Multihull Sailboats 18 05-10-2014 17:12 Philip R. McGovern Deck hardware: Rigging, Sails & Hoisting 18 14-10-2010 06:16 shibbershabber Construction, Maintenance & Refit 12 14-03-2010 21:56 No Threads to Display. - - - - - - - Privacy Guaranteed - your email is never shared with anyone, opt out any time. 325 COMMENTS What "good" bridgedeck clearance is and why is it important? The bridge deck is essentially the part of the catamaran that you stand on. It is the space between the hulls. It's not just the saloon but also the cockpit and the forward anchor lockers. ... So those are the priorities. A high bridge deck underneath, a sloping front that starts as far back as possible, and a higher cockpit then is a good thing. Bridgedeck Clearance The potential of the catamaran hull form, which is so impressive when sailing at 8 to 10 knots in 20 knots of breeze in protected waters, can be quickly reduced to 5 knots by pounding. Yes, a very low bridgedeck cat can lose 3 to 4 knots of boat speed with a major pound. Read more about bridge deck clearance. Why Bridgedeck Clearance is Crucial in Catamarans: Explained Avoiding slamming or pounding of waves against the underside of the bridgedeck, can make all the difference for the comfort of the crew and safety of the vessel. The slamming phenomenon can both be nerve wracking for the crew and damaging to the boat. As a rule of thumb, we believe that clearance of between 5 and 6% of the LOA of the catamaran ... Catamaran Structure Part 3: Building a Bridgedeck. Building the bridgedeck is the key piece of fiberglass catamaran strength. To be able to build a boat which can handle all these twisting and torsion forces, creating that "box" to add the strength, catamaran builders take one of several approaches. Choosing a Cat I would love to have a higher bridge deck clearance, but taking stuff off the catamaran involves people giving up some of their stuff. Not easy. I would love to have a higher bridge deck clearance by getting a bigger cat, but then there are all sorts of new challenges sailing and taking care of a larger yacht, not to mention the much bigger ... Catamaran Parts Explained: Interactive Guide (For Beginners) The cockpit contains navigation and steering equipment and is from where the sails, rudder, and engine are controlled. Deck; is the top part (roof) of a catamaran covering the hulls and bridge deck. The deck is made hard enough to walk on. To the deck, attaches lifelines and other equipment. PDF The Space Between The Space Between. An In-Depth Look at Bridgedeck Clearance for Catamarans. CurrieBridgedeckclearance (the height of the bridgedeck above the water) is crucial for cat-amaran seaworthiness and cr. w comfort at sea. Because bridge-deck clearance can be seen at a glance, and is easily measured, even an inexperienced sailo. Mike Waller Yacht Design The WALLER 880 Cat is a full length bridge deck catamaran designed for family coastal cruising, with the occasional foray further afield. Full length bridge decks have several advantages in smaller cats, in that they provide a stronger hull structure, more deck space, are easier to construct and eliminate the need for expensive bow beam structures. Did you know? #1 Bridgedeck Clearance Bridge deck clearance ratio (BCR) starts to be good from 6% of LOA. On our models, the bridge deack clearance is as follows: ORC50: 37,4 inches. ORC57: 42,1 inches. Should you have any questions about other measures, or want to know more about our boat specs, please let us know! Speak to you soon. Fair winds, What Is a Cruising Catamaran? Everything You Need To Know Cruising catamarans should have a high bridge deck clearance. If the bridge deck clearance is too low, the waves may pound against the bottom of the bridge deck. This pounding can cause discomfort and fatigue for the passengers and crew and potentially reduce the catamaran's speed. The height of the bridge deck clearance needs to be ... open bridgedeck catamaran design I have put together a design for a catamaran to meet my list of requirements: 1. catamaran, max 34 ft. LOA, 21 ft. beam. 2. good bridgedeck clearance…32 inch minimum. 3. minimum open bridgedeck, well back from bow and stern. 4. center of gravity at or below bridgedeck, with all tankage, engines, food storage near waterline. Waller 880. 29 ft cedar strip / glass bridgedeck catamaran The WALLER 880 Cat is a full length bridge deck catamaran designed for family coastal cruising, with the occasional foray further afield. Full length bridge decks have several advantages in smaller cats, in that they provide a stronger hull structure, more deck space, are easier to construct and eliminate the need for expensive bow beam structures. Sailing Catamarans Strike 15 trimaran at speed. 28ft Skoota in British Columbia. 10ft 2 sheet ply Duo dinghy. 24ft Strider sailing fast. 36ft Mirage open deck catamaran. Bridgedeck Slamming. People are right to be concerned about bridgedeck slamming on catamarans. Having said that, it is usually a comfort problem rather than a structural one. Evaluating modern catamarans Bridge deck clearance (BDC): BDC affects the amount of noise in the boat from wave slap, especially while going upwind. We think a catamaran with about 30 inches of clearance is ideal. Increasing the BDC means more windage, which is a negative. Much less than 30 inches, and wave slap becomes a problem in rowdy sea conditions. CATAMARAN DESIGN and BRIDEDECK CLEARANCE (1) Interested in comments from Catamaran owners re Bridge deck clearance. I have heard reports about low bridge deck clearance causes Slamming and pounding of significant proportions when sailing to windward. Comments please. (2) Some designs have .500m clearance others .700m and I notice the latest designs on some are rising to .950m and 1.2m Bridge Deck Clearance ? How Much 40-50ft ! HOW MUCH 40-50ft ! Bridge-Deck clearance on a Catamaran. Lets face it guys, most of the Production Cats do not have enough clearance or the have many shelves, bumps, and things that should not be there. If it is slamming, it is causing Drag as well. My 381 Catana does not slam with 800mm of clear space between the hulls. Rotten Bridge Deck Catamaran? Rotten deck core. How detrimental? gansett: Construction, Maintenance & Refit: 37: 02-07-2020 23:56: Ocean-Going Catamaran Size and Bridge Deck Clearance: tallboy: Multihull Sailboats: 18: 05-10-2014 17:12: Rotten Deck Core Around Windlass: Philip R. McGovern: Deck hardware: Rigging, Sails & Hoisting: 18: 14-10-2010 06:16: Rotten Deck & Cabin ... Top 6 Characteristics of a Good Catamaran Catamaran Bridge Deck Clearance. ALL catamarans slam (waves hitting under the bridge deck). The noisy and sometimes disconcerting slamming takes getting used to. The first catamaran I ever sailed an ocean passage on was a Shuttleworth 44. In the early 90's and even today, it is considered to be a good design. However, after a few hours of ... Lifting a catamaran from under the bridgedeck Posts: 11,832. Re: Lifting a catamaran from under the bridgedeck. All you have to do is make sure they catch it at the main structural beams. Those are the bulkheads that go all the way across the boat from port to starboard. One is located all the way aft. The other is located typically underneath the mast. Bridge Deck Slap- Gemini Catamaran Bridge Deck Slap- Gemini Catamaran. Gemini sailing catamarans of Yacht A Fun's 1997 vintage were designed such that small wave ripples are caught in the square shoulders of the inner hull transition. When at sea, the small sounds are masked somewhat by the boom sound of the bridge deck being pounded by full sized waves and swell. Brix Marine Hammer Catamaran 3814 Brix Marine 3814-CTC-Offshore-SWA 2023 Brix Marine Hammer Catamaran now available! Twin Mercury V12 600 HP Length 38' Beam 14' Self bailing aluminum decks BEACHCOMBER landing gear for foot traffic... CL. chicago > north chicagoland > for ... Custom Fly bridge bench covers 1-port, 1-stbd, Stamoid Black c/w SS fasteners & PTFE thread. Ocean-Going Catamaran Size and Bridge Deck Clearance Location: Kingston / Thousand Islands, Ontario. Boat: C&C 35 Mk.II. Posts: 343. Re: Ocean-Going Catamaran Size and Bridge Deck Clearance. Regarding bridgedeck clearance: Recommendations vary, but the consistent advice from most sources is along the lines of "the bridgedeck shouldn't slap on the wave crests". Rotten Bridge Deck Catamaran? Join Date: Nov 2023. Posts: 10. Rotten Bridge Deck Catamaran? I'm considering buying a 1990s catamaran - first boat so please help! It has balsa cores above the waterline. Solid fiberglass below. The outside decks all feel strong no sponges bits.BUT the bridge deck cabin sole is spongey and lifting the carpet shows the below. catamaran gulet motorboat powerboat riverboat sailboat trimaran yacht