the moth sailboat

MACH2 Essentials

All you need to know about the Moth class and Mach2 in particular. All the essential information regarding the boat, it's history, evolution of foiling, the designer, the sailmaker and the boat builder. There's even an introductory video and a few testimonials. Enjoy!

The Designer

Andrew 'AMAC' McDougall first became involved with the Moth class when he built his first Moth at the age of 15 in 1970.

Need some parts for your Mach2? We have a full compliment of sails, spas, foils and Mach2 spares available online.

Speed Demons

36.6 ned goss.

Is this a world record speed for a dinghy? Ned Goss in a 18-25 knot Charleston sea breeze hit a peak speed of 36.5 knots, with a 10 sec average of 35.9 knots in his MACH2. Goss’s Velocitek files were verified by Bora Gulari & Velocitek founder Alec Stewart. Take that!

30.2 Josh McKnight

Following his win at Lake Garda, 2012 World Moth Champion, Josh McKnight then set an outstanding top speed and ten second average on his Mach2. It goes to show the Mach2 / KA Sail is a killer combination!

31.5 Scott Babbage

Scott Babbage set this speed sailing his MACH2 on Sydney Harbour whilst training with Josh McKnight. Any top speed that's above 30 knots is well worth a mention, but to have a ten second average that is also above 30 knots, wow!

31.4 Hiroki Goto

Sailing at a lake in Japan near Mount Fuji, Hiroki Goto, set a very impressive top speed of 31.0 knots, only to surpassed his on record the following day with a top speed of 31.4 knots and a ten second average of 28.4 knots.

MACH2.6 Is Here

This is the fifth major upgrade in the illustrious life of the Mach2 Moth. Already it's proving to be dominant. For the complete list of upgrades and features, hit the link below

Testimonials

We take a great deal of pleasure designing, building and supporting the best foiling Moth in the world. And nothing gives us greater pleasure than the positive feedback we have received from MACH2 owners over the past 10 years. Here's a few owner testimonials........

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VIDEO: Meet the Moth, the fastest solo sailing dinghy in the world

The International Moth sailing class reaches speeds of over 30 knots and spectacular drone footage of sailor Paul Farien ‘mothing’ on Lake Garda has set the internet alight this week.

From Superinnovators 19/06/24.

According to the International Moth Class Association, the Moth is the fastest single-handed sailing dingy in the world, with a top speed record of 31.1 knots, achieved in 2011.

And incredible drone footage of Germany’s Youth America’s Cup team lead, Paul Farien, skipping across Lake Garda in the eXploder mD3 Ovington Moth, has clocked up millions of views online this week.

One TikTok user commented: “Bro is sailing on a pringle,” in reference to the eponymous curved wing deck used to lean on when tacking.

The class first emerged in the 1920s, but it wasn’t until enthusiasts started adding hydrofoils to their home-built moths in the 2000s that things began to take off.

The hydrofoil consists of a set of small underwater wings, front and back, that lift the entire hull out of the water, reducing drag, and boosting speed and agility.

Although some still build their own moths, several commercially manufactured boats are also available.

They’re serious bits of kit, with the eXploder mD3 Ovington Moth, retailing at £26,095 (approx. $33,218).

View this post on Instagram A post shared by Paul Farien (@paul_farien)

The next Internation Moth event sure to feature more eXploder mD3s among other models is Foiling Week, hosted by FV Malcesine sailing club on Lake Garda, Italy, 24-30th June.

Thanks to Paul Farien and Patrick Lombardi (drone) for highlighting the Moth to us and we wish Paul all the best in the Youth & Puig Women’s America’s Cup, Barcelona, 17th Sept – 13th Oct.

https://ovingtonboats.com/int-moth

http://www.internationalmoth.co.uk/

http://www.moth-sailing.org/

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Classic Moth Boats

Classic Moth Boats are a class of small fast singlehanded racing sailboats that originated in the US in 1929 by Joel Van Sant in Elizabeth City, NC. The Classic Moth is a monohull development class using a modified version of the International Moth rule in effect pre 1969. With an eleven foot over-all length, a maximum beam of 60 inches, a minimum hull weight of 75 pounds, 72 Sq Ft sail area, and very few other restrictions a Classic Moth can be a skiff, pram, scow, skinny tube, dinghy, or any combination thereof. The Classic Moth Boat is an ideal class for amateur designers builders and tinkerers, and can be easily built from inexpensive materials.

If you wake up in the middle of the night with a novel idea for hull shape, you can leap out of bed, race down to your garage, build it and then find out at the next regatta if your idea is hot or not. Freedom of design sets Moths apart from the clorox bottle (one-design) crowd. Instead of the one design controlling who sails successfully, we design and build Classic Moths that fit our size, ability, taste, skills, artistic expression, and pocketbook.

To broaden the appeal to race all types of Classic Moths, we have created three divisons within the class. At major regattas, all Classic Moths race together but are scored in three different divisions; a Gen 2 division for full on narrow waterline, low wetted surface designs, a Gen 1 division for more stable, higher wetted surface designs, and a Vintage division for restored Moths built before 1950.

Presently, Classic Mothboats race in many locations up and down the east coast of the United States. Regattas are currently held in Brigantine, NJ; Portsmouth, VA; Chestertown, MD; Cooper River, PA; Augusta, GA; Norfolk, VA; Elizabeth City, NC; Charleston, SC., and St. Petersburg, FL. Please refer to the regatta schedule on this site for dates and contact information.

Latest News

2022 mid winters results.

2021 Nationals Results

2020 Nationals Results

2019 race schedule..

We have quite a race schedule for 2019.   

Check it out under Schedule. 

Happy Sailing  

Susla Cates in FLA -- a nice boat for somebody -- FREE --

I finally have gotten my Dad's blessing to send the Moth on to a new owner.  Unfortunately, we did not take the boat down from its ceiling perch, so I do not have any additional photos for you. My parents are scheduled to close on their house on 8/29.  I think the new owners, who are our neighbors, would be fine if the boat was picked up soon after the closing, but if somebody miraculously could pick it up prior to 8/29, that would be amazing.   Laurie S < This email address is being protected from spambots. You need JavaScript enabled to view it. document.getElementById('cloak10af5d96e9b12508c6240cdd5b80aecb').innerHTML = ''; var prefix = 'ma' + 'il' + 'to'; var path = 'hr' + 'ef' + '='; var addy10af5d96e9b12508c6240cdd5b80aecb = 'lcsusla' + '@'; addy10af5d96e9b12508c6240cdd5b80aecb = addy10af5d96e9b12508c6240cdd5b80aecb + 'gmail' + '.' + 'com'; var addy_text10af5d96e9b12508c6240cdd5b80aecb = 'lcsusla' + '@' + 'gmail' + '.' + 'com';document.getElementById('cloak10af5d96e9b12508c6240cdd5b80aecb').innerHTML += ' '+addy_text10af5d96e9b12508c6240cdd5b80aecb+' '; >  952-212-9849   If anyone has any in-depth questions, I will get my Dad on a 3-way call with the prospective owner, however, his memory is starting to fail a bit, so there are no guarantees he can answer all questions.

We are not looking for any money, we just don't want to throw the boat in the dumpster.  As I mentioned before, it's mahogany, with no mast, boom, or sail.  It really is still quite pretty, since it's been stored indoors its whole life.   

Ed Salva - Belgium Roland Europe wood deck nick named Harry Winston

Roland Europe  with wood foils  a Forté carbon mast that is stiff and a Europe sail.

Contact Ed Salva @ Julypeapod@gmail .com. 

Jean Gruhler's Ventnor -- Ventnor Moth # 661, Maine

For sale: Ventnor Moth # 661, built by Ventnor Boat Works in West Atlantic City NJ in 1944.

The boat was rebuilt (restored) by Jean A Gruhler in both 1967 and 1991, found its way to Maine in 2014.

She would like to sail and race again, but we do not have the time.

It has a new paint job, by a professional boat builder.

Sails, spars, both rudders all in very good condition.

Has a cradle

Sale price $1,100.

early Ventnor

This is an early Ventnor with an unknown registration number. 

Sun Fun Sailor built from plans in Science & Mechanics Oct 1962

Hi, I wish to advertise and sell my Moth built by my brother in the 1960’s   For Sale : Sun Fun Sailor built from plans in Science & Mechanics Oct 1962.   Includes trailer and 2 sails. Wood construction hull, mast and boom. Hull bottom was fiberglassed when built in the 1960’s.   Located in Appleton Wisconsin.   Asking $900.00.      Contact Ron Aavang @  This email address is being protected from spambots. You need JavaScript enabled to view it. document.getElementById('cloak1a0322c20294df2ea928d137ec2ba566').innerHTML = ''; var prefix = 'ma' + 'il' + 'to'; var path = 'hr' + 'ef' + '='; var addy1a0322c20294df2ea928d137ec2ba566 = 'raavang' + '@'; addy1a0322c20294df2ea928d137ec2ba566 = addy1a0322c20294df2ea928d137ec2ba566 + 'new' + '.' + 'rr' + '.' + 'com'; var addy_text1a0322c20294df2ea928d137ec2ba566 = 'raavang' + '@' + 'new' + '.' + 'rr' + '.' + 'com';document.getElementById('cloak1a0322c20294df2ea928d137ec2ba566').innerHTML += ' '+addy_text1a0322c20294df2ea928d137ec2ba566+' ';  or call cell # (920)904-2167.

Member Links

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World’s coolest yachts: International Moth

• September 2, 2021

We ask top sailors and marine industry gurus to choose the coolest and most innovative yachts of our times. Paul Larsen nominates the International Moth

“There are so many boats out there that have cool aspects and yet remain horribly compromised or are no longer relevant. After a ridiculous amount of consideration (and excluding our own creations) I have to go for the foiling International Moth,” says the world’s fastest sailor , Paul Larsen.

“Like foiling or not, you can’t shoot the messenger! As a cool boat it stands on its own, and for what it has since inspired.

The International Moth has done more than any class to raise the profile of sailing hydrofoils. Photo: Thierry Martinez/Sea&Co

“The concept just works so well. Its performance and accessibility inspired sailors, backyard builders, designers and performance sailing in general.

“Buy a good one to race at your club or against the best of the best.

“This little foiler came to the local skiff/cat party and smacked all the old cool kids down. Things change when that happens.”

Make sure you check out our full list of Coolest Yachts.

International Moth stats rating:

Top speed: 30.7kn LOA: 3.4m Launched: 1971 Berths: 0 Price: €20,000 Adrenalin factor: 90%

Paul Larsen

Australian Paul Larsen is the world’s fastest sailor. In 2012 he sailed Vestas Sailrocket II to a sailing speed record of 65.45 knots .

His first taste of multihull speed was in the Eighties, delivering the 86ft Commodore Explorer to Japan with Skip Novak .

He competed in major ocean racing events before developing Sailrocket to make its record-breaking run.

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INTERNATIONAL MOTH SPEED GUIDE

Moth Dinghy expert Rob Greenhalgh introduces this extraordinary singlehanded foiling dinghy and describes the keys to sailing one fast.

Who sails the foiling Moth Dinghy?

The Moth class is for everyone—it’s so exciting, you don’t need to race it. Club sailors can get a huge buzz out of foiling, going fast around the bay, and learning to foil jibe and tack. They might enjoy it so much they never need to join a race. At the other end of the spectrum, there are sailors who have been in Moth Class for a decade or more and love the challenge of racing this exciting, complex craft. 

Viewed from stern or bow, the foiling moth is a high-speed machine, clearly unlike other sailboats.

What kind of sailors enjoy this challenge?

Moths are development boats, not a strict one-design class, and that’s daunting for some. The technical and evolutionary side of Moth sailing requires a good understanding of how everything works—how the foils interact with the rig setup and how to balance both aspects. Over the last five years, there have been massive speed advancements, which will continue. To be at the top of the game, you have to enjoy the technical side. But you can buy equipment off the shelf and, if you practice and sail well, soon be up to pace. Though more technically oriented sailors often gain an edge for a while, there are also lots of people who will make changes that don’t help them, so it evens out.

How physical is the sailing?

When you are first getting into it, Moth sailing seems physically hard, but once you’ve done it a while, it’s not too bad. On a windy day with a lot of capsizing, it gets pretty tiring. But it’s a light boat, and the loads are not high. Anyone can do it if you can move quickly at times. There are plenty of Moth sailors in their 60s.

New boats or used, which are better?

My advice for the first-time or second-time buyer is to look for a good second-hand boat that you know will fly. This saves you a lot of effort, because even experienced Moth sailors need a few months to work up a new boat. Sure, it’s always a worry that you might not be getting good enough kit with a used boat, but in my experience, any modern Moth can be made fast. If you want to buy new, a standard boat from either of the two main builders—Exocet by Maguire Boats, or Mach 2 by MacDougall McConaghy—will quick enough for top 5. You can also have a look at the new Bieker Moth by LSF Composites.

The Moth is a development class. What’s happening lately?

The Vi-8 DS 3Di (on top) and Vi-8 LA 3DI feature the same sail area. The LA has more power in lighter winds to foil more quickly; the DS has less drag at high speeds.

What sails do you recommend?

8LA-3Di provides extra power to get on foil.

Which sails do you use?

The decksweeper (Vi-8 DS 3Di) creates an endplate and lowers aero-drag. It is slightly faster once foiling.

How does foil choice affect sail choice?

Moths have two foils, a larger foil for lighter winds and a smaller foil for stronger, and that’s a choice you have to make on the beach. In my case, if I expect to be on my foils all day, I’ll choose the smaller foil and the deck-sweeper sail. If the winds are lighter or less reliable, I will often choose the big foil and the LA sail. And if I expect light air to start but a building breeze all day, I’ll likely choose the big foil with the deck-sweeper sail.

Tuning the Moth Dinghy

What are the keys to tuning a moth.

Generally speaking, you should set up your boat to carry as much rake as possible. How much is that? You’ll know it’s too much if you can’t get under the boom in tacks and jibes. This is not something you do underway, and if the boom is making boat handling more difficult, make the rig more upright until that smooths out.

What other key adjustments do you make before launching a Moth?

Batten tension is one. For Batten 1 (the top batten) down to Batten 5, just take the creases out of the batten pockets—don’t over-tighten them. For Batten 6, remove the crease and then add two more turns by twisting the batten key two full revolutions in a clockwise direction. For Batten 7, take the creases out and add three turns. The outhaul is also non-adjustable underway. Rig the boat ashore with the outhaul loose. Pull on max vang and max cunningham, and then pull the outhaul tight. This will give you a good all round setting.

What other settings can you recommend?

Here some of the numbers from my boat, but don’t worry if your measurements are different. Comparing measurements boat to boat may not matter at all. The important thing is to start recording them and experimenting.

• Front Prodder 340 (adjustable +/-50mm)
• Side Arm 410mm
• Deflection 220mm
• Shroud Base 1500mm
• Mast Length 5100mm (excluding plastic plugs top and bottom)
• Back of mast to clew ring 2340mm

From mast length to shroud base, it's important to record all of your boat and rig measurements. You will change them over time.

How do you set up your foils, actuator wand, and gearing?

Sailing in rougher water requires faster gearing between your actuator and main foils. Foil gearing is a critical control for waves; make sure it can be adjusted for rough waters. To get through waves you need faster gearing. You’ll also change foil size depending on the wind forecast. I have two sets of main foils and use the smaller one on windier days. However, if the wind is light for the first race and predicted to build, I’ll go with the larger foil because the speed penalty of not being able to fly with other boats can trumps all other considerations.

Upwind Moth Sailing

What is most important when sailing upwind.

On any point of sail, the vang and cunningham are powerful controls, and need constant adjustment for different conditions. The goal is to generate power for low-riding and to get up on the foils, and then flatten the sail as the wind builds. One of the challenges of the Moth is it has a maximum 8.25 square meters of sail area, and upwind in most conditions, that’s more sail than you need. Downwind, you have the opposite problem; your speed reduces the apparent wind so much, you’re always starved for power.

What is low-riding mode and how do you sail fast in light winds?

In general you don’t race in winds when you can’t foil, but it may happen that the wind lightens up substantially during a race. Sailing in low-riding mode is an art in itself, something like balancing in a canoe because the hull is so narrow. I always recommend practicing sailing that way.

What does it take to fly a Moth?

Heel the Moth to windward to keep the boat more stable and reduce leeway.

Why do you tip the Moth to windward when flying?

We sail with the rig always tipped to windward because it keeps the boat more stable and reduces leeway on the main foil. Use very subtle steering and trimming of the main.

How do you trim the Moth sailing upwind?

Correct trim is the absolute key to good boatspeed. It’s very easy to over-sheet and stall the front of the mainsail. Always have the inside tell tales lifting. A common mistake is sailing under-powered and over-trimmed. As the wind increases, flatten the main by tightening vang and cunningham to accommodate the higher apparent wind speeds.

How do you adjust sail trim for gusty winds?

You need your rig set-up to be user friendly. That means having enough vang and cunningham to straighten the sail. If twisted, the center of effort can move up and down the sail. It takes a certain level of confidence to get to the point where you can let go of the mainsheet to tighten the kicker and cunningham.

Downwind Moth Sailing

What is the key to good moth speed downwind.

Sailing downwind, be sure to maintain a big entry angle in the lower part of the sail and avoid over-trimming.

What is your focus when trimming downwind?

I focus closely on my lower tell tales, keeping them flying 100 percent and making sure I ease enough to keep the sail ‘hooked up’ with airflow attached. I look for a nice big entry angle on the bottom part of the sail and clean up any horizontal creases by subtly tightening the cunningham. From there, it’s a matter of very subtle trim and steering. If in doubt, ease the sheet and be sure you have good flow going around the front of the sail. If you run into a light patch, just head up to keep the flow going on the main. If needed, power up the main even more. Get the gearing really slow on your foils to minimize drag. The boat will go faster and apparent wind will increase, moving the wind forward and letting you trim harder. Especially when it’s a bit lighter downwind, be sure to pre-empt a drop in apparent wind by easing main and bringing the bow up!

Moth Tacking, Jibing And Gear Changing

How do you foil jibe a moth.

When foil tacking or jibing, you need to flatten the boat. For jibing, bank into the turn to leeward. You’ll turn the boat more aggressively when your body is ready to move across to the new wing.

How do you foil tack a Moth?

When tacking you have to move quickly, bringing the boat relatively flat once head to wind. Start luffing slowly, taking the edge off your speed; make sure the boat is flat when head to wind. As my body moves across the middle to the new wing, I’ll increase the rate of turn, steering quite aggressively through the eye of wind, but my body has to be ready to cross the boat and receive the power on the new tack. You need to come out tipped to windward. Here’s how I break it down:

• Ten seconds before tacking, consider slowing the boat slightly and sailing slightly higher.
• Plan for a slow luff head to wind, followed by a faster turn rate once confident that crew weight can be positioned correctly.
• Heel to windward before the tack but flatten the boat once head to wind. Move your weight inboard. It is important here to sheet the mainsheet on centerline so that it is not over the leeward wing when you pass underneath.
• As you move across the middle of the boat, pass the tiller extension around the back and into a position halfway along the leeward wing.
• When you are confident you can move to the new side, increase the rate of turn, landing on a wider than close-hauled course.
• There are a lot of G-forces during this period, so expected to get ejected a few times!
• Don’t try to piece the whole tack together immediately. Practice the first phase of luffing head to wind, getting your weight to center, and switching the tiller extension across.
• Remember to ease mainsheet out of the tack and have your hands positioned so that the sheet can be eased quickly. The sheet is more important than the tiller on exit.
• I set my mast rake to allow 70 to 75cm between the boom and the deck where I cross the boat. Tacking is important, so make sure you have room under the boom! For tacking practice, I recommend having the rig more upright.
• Don’t adjust any control lines right before or after tacks, unless it is very light and foiling is marginal.

Name 5 key gear changes in a Moth

• To foil early in light air, power up by having the vang and cunningham as loose as possible. However, it is easy to over-deepen the front of the sail, requiring further bear-away to get good flow on the sail. Don’t overdo it.
• Downwind always requires a deeper sail shape than upwind, regardless of wind speed.
• Once foiling, immediately pull on vang to stabilize the sail and cunningham to clean the creases. Even though the wind is light, we are quickly doing 14/15kts. The AWS is high so we need to change sail shape to achieve good speeds.
• As the breeze builds, constantly increase vang and cunningham loads to achieve the desired sail shapes. Max vang should be achieved in 15 knots and max cunningham in 18 knots.
• The Moth gets overpowered quickly, and from 18 knots upwards a softer tip or different sail is required. North’s LA and DS designs have a slight variation in the luff rounds to cover the range, with the DS being aimed at 14 knots true wind speed. For lighter sailors, a softer-tip allows the mast to bend earlier and depower the sail.

How do you start a race in a Moth?

Starts are a bit chaotic. Even for long-time racers, a Moth start will be a new experience. People get up on their foils with about 25 seconds to go and do a big turn-up at about 3 seconds, crossing the lining at 20 knots. A key thing when you’re on your foils is to have the ability to slow down while maintaining control. You need to practice that. Getting to the pin too soon is dodgy, especially with boats starting on port tack.

Why do so many Moths start on port tack?

Moths travel at 15 to 18 knots upwind, so tacking is a very costly part of an upwind leg. Reducing the number of tacks during a beat is very efficient, although this depends somewhat on how well you tack and how confident you are in making your tacks.

How many ways can you capsize a Moth?

You will capsize a Moth every possible way when learning. But I can sail for days now without capsizing, unless it is windy and choppy. The key to recovering quickly is to get on the daggerboard and do a dry capsize, climbing back over the wing. Sometimes that’s hard to do, especially when you pitchpole and find yourself 20 meters out in front of that boat.

What is the most common boat-handling mistake in a Moth?

Capsizing! Foil tacking, in particular, is very difficult. A common mistake is trying to foil tack when it’s breezy. Drag is so high that as you go through head to wind, everything slows down and it’s easy to capsize. You may be better off planning to do a touch-and-go tack. 

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The current International moth is a result of merging two separate but similar historical developments. The first occurred in Australia in 1928 when Len Morris built a cat rigged (single sail) flat bottomed scow to sail on Andersons’ Inlet at Inverloch, a seaside resort, 130km from Melbourne. She was hard chined, was eleven foot long, and carried 80 sq ft in single mainsail. The craft was named “Olive” after his wife. The construction was timber with an internal construction somewhat like Hargreave’s box kite. “Olive’s” performance was so outstanding, that a similar boat “Whoopee” was built. Len Morris then sold “Olive”, and built another boat called “Flutterby”, and with those three boats, the Inverloch Yacht Club was formed. Restrictions for the class known as the Inverloch Eleven Footer class were then drawn up, with the distinguishing characteristic that of being not a one-design boat but rather that of a boat permitting development within the set of design parameters. At much the same time, 1929 in fact, halfway around the world another development class, the American Moth Boat was started by Captain Van Sant of Atlantic City, New Jersey with his boat “Jumping Juniper” built of Atlantic White Cedar from the Great Dismal Swamp. The US development class was formally organized in 1932 as the “National Moth Boat Association” and in 1935, due to increasing overseas interest, changed its name to the “International Moth Class Association” or IMCA.

In October of 1933, an American magazine, The Rudder, published an article dealing with the Moth Boat scene in US. The Australians noted the similarities between the two groups of boats and intuitively realized that the name “Moth Boat” rolled more easily from the tongue than “Inverlock Eleven Footer Class”, so they changed the name of their class to Moth and adopted the “squashed bug” that was shown in the article as the class sail insignia.. The Australians also noted the differences, particularly in sail plan between the two boats, but since this was in the middle of the great depression, and the two groups were 13,000 miles apart, no attempt was made to reconcile these differences. The US fleet, and later the British and European moths, adopted a “circle M” for their sail insignia. Thus two large Moth classes developed separately for over 30 years.

Also, in the early 1930s a small group of sailors in Great Britain formed a “British Moth Class”. The British class was restricted to a particular hull shape of a 1930s Vintage American Moth Boat, and is thus not a development class. Meanwhile, in Australia, in 1936 the Victorian Moth Class Association was formed, but it was not until after WWII, that the NSW Moth Class Sailing Association was formed with foundation members coming from Seaforth Moth Club and Woolahra Sailing Club. During this time Australian Moths were using pre-bent and wing masts in the 1950s. From 1956 to 1961 all other states formed Moth Associations and in 1962 the Australian Yachting Federation (AYF) recognized the Australian Moth class as a national class, the FIRST small boat class in Australia to be granted national status.

After the Second World War, more and more European interest in the Moth Boat was expressed. The European Moth clubs subscribed, more or less, to the US class rules. One European Moth design from the early 1960s, the “Europa Moth”, broke away from the IMCA and formed the one-design Europe dinghy class and became the woman’s single-hander used in the Olympic games from 1992-2004. Also in the 1960s, the Australian Mothists began campaigning for rules changes that would permit the Australian Moths to compete in the IMCA’s “World Championships”. In 1971 the US-based IMCA completed a phase-in of new rules which attempted a “marriage” of the IMCA and the Australian Moth. This amalgamation process had started at the annual IMCA meeting in 1965. New rules embraced the more powerful high aspect, loose footed, fully battened rig of the Australian Moth and the squashed bug insignia. The new rules also permitted controversial hiking wings first seen on Moths from Switzerland. Finally, the rule change abolished the US centralized organization of the class in favor of an independent world body with equal-partner national associations. Each national association elected its own officers and world body representatives. The culmination of these changes was the recognition in 1972 of the IMCA by the International Yacht Racing Union (the forerunner of today’s ISAF) bound by the agreed upon new restrictions of the class (with metric measurement conversions) operating today. The moth class association that had originated in the US was now truly an international organization.

Being a development class, the moth has evolved from a hull in the 1930’s that could best be described as a heavy, narrow scow or a blunt nosed skiff, (weighing about 50 kg) to today’s remarkable foilers with hull weights of under 10 kg,. Designs have run the gamut from wide skiffs without wings, to lightweight scows, to wedge-shaped hulls characterized with narrow waterlines and hiking wings out to the maximum permitted beam. Likewise, the sail plan has evolved from cotton sails on wooden spars, through the fully battened Dacron sails on aluminum spars stage, to the windsurfer inspired sleeved film sails on carbon masts seen today.

The International Moth has fostered a number of remarkable achievements. For example, in 1966-67, The King of Siam was involved in the building of three Moths and sailed them on the pond at Chitrlada Palace. The King raced for almost 20 years on his second moth called ‘Super Mod’ until his design and construction efforts were cut short by the ‘press of royal duties’. In 1957 Patricia Duane became the first women to win the moth world championship in her Cates-Florida design and in 1968 Marie Claude Fauroux became the first woman skipper to win a World dinghy racing title from a IYRU sanctioned international class – in her Duflos designed moth. The International Moth was selected as an official training class for the Japanese Olympic sailing team, to hone their balance skills. And of course, the moth has become the standard of a successful hydrofoiling class, with most foils and control systems based on developments by John Ilett in Australia.

Hydrofoil sailing boats in the moth class sailing world championships changed the America's Cup forever

Topic: Sport

When Brett Burvill won two races at the moth class sailing world championships in Perth almost 20 years ago, he could not have known how a small change he made to his boat would reverberate around the world.

"He finished 10th [overall], which is pretty good for a crazy new development, but he won at least two of the races I think," recalled friend and fellow boat builder John Ilett.

"They were really spectacular, because he would not go very well at the first part of the race, and then the next part he would pass 20 boats, and then another 20 boats.

"He was just twice the speed."

Next week, more than 100 competitors will return to the Mounts Bay Sailing Club for the 2019 World Championships, two decades after Burvill unveiled his revolutionary innovation.

He had attached a hydrofoil to his boat, which provided lift, reduced drag and dramatically increased his speed.

Moth boats use a hydrofoil to skim through the water off the surface. ( ABC News: Tom Wildie )

It also set in motion innovations which made their way to the biggest race in global yachting.

Superfast hydrofoil caused a stir

Burvill wasn't the first person to put hydrofoils on a boat, but he was the first to successfully race them.

"There were ones done in the 1970s, with moths, and ones in the 1990s, but these were never sort of proven in racing," said Ilett, who was an early adopter of hydrofoils.

"People experimented with it but until you actually sail around a course and win a race or win a regatta, then that's when the concepts are proven and adopted.

Moth racers Brett Burvill (left) and John Ilett show off the hydrofoil that is the key to the moth boat's speed. ( ABC News: Tom Wildie )

"I think it was just the inspiration of other crazy boats flying around, because it had been done to other craft but it had not been done in the moth class.

"The moth class is open to any new development, so if you can make them go faster, then we gave it a try."

The attachment of foils to the moth boats brought plenty of resistance, with some competitors concerned the increased speed and difficulty of control would kill the class.

"There was a lot of backlash to it in the beginning," Ilett said.

"The class wanted to ban it, some people wanting to ban it, people walking away from the class and saying I'm never coming back, so there was a lot of fuss about it."

So how do hydrofoils actually work?

Hydrofoils are not a new invention, with their use first recorded 150 years ago when a British patent was granted to Frenchman Emmanuel Denis Farcot.

He claimed that adapting to the sides and bottom of a vessel a series of inclined planes or wedge-formed pieces would have the affect of lifting it in the water and reducing the drag as it went forward.

Inventor Alexander Graham Bell, who is best known for the telephone, also built a foiled boat called a HD-4, which set a marine speed record of 114 kilometres per hour in 1919.

Since then, the technology has been used in military and passenger capabilities, but there prevalence has declined over time, with the foils susceptible to impact and also posing a risk to marine life.

Hydrofoils work in essentially the same way as aeroplane wings.

As the boat moves forward, the hydrofoil travels through the water, but the water that travels over the top does so at a faster speed.

The faster the water travels, the lower the pressure, resulting in an area of low pressure above the foil and high pressure below the foil.

The difference in pressure creates lift, allowing the boat to rise out of the water.

With the hull of the boat out of the water, drag is reduced, and vessels can reach higher speeds.

Making it to the America's Cup

The successful application of hydrofoils in the moth class demonstrated their value to racing and saw them adopted across numerous sailing classes.

But it was their use in arguably the world's most prestigious race that completed their emergence in mainstream racing.

"It's pretty cool," Ilett reflected.

"I think it probably seemed inevitable. I think I'm right that in the early days of the America's Cup they did try to stop the hydrofoil developments, but like the America's Cup do, they found a way around it."

Those changes were implemented in 2013, when America's Team Oracle completed a remarkable 1-8 comeback to claim the event 9-8 over Team New Zealand, with the yachts reaching speeds of about 80kph.

Oracle Team USA successfully defended the America's Cup on a hydrofoil-powered ship in 2013. ( Reuters: Peter Andrews )

The adoption of the hydrofoil in the Cup has a benefit for those who still race the moths, with successful skippers often hired to compete in the big race.

"It's put a lot of America's Cup sailors into the moths class because it's easier to get the guys out on one of of these more often — for training, for learning and getting a feel for flying," Ilett said.

"Even the guys on the America's Cup boats that don't do particular jobs, they all sail on these boats too."

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Bladerider Moth Sailboat

• By Alan Block
• Updated: August 21, 2007

Even the staunchest keelboat devotee can’t help but be intrigued by them. They don’t have a trapeze, and they’ve only got one little sail, yet they sail at twice the true wind speed. They’re monohulls, but they move faster than a Tornado cat, sailing upwind as fast as 13 knots, downwind close to 30 knots. Jumping out of the water on ultra-light carbon foils in a 5-knot breeze, they’ll smoke almost anything else powered by sails.

They’re International Moths, and if Andrew “Amac” McDougall of Bladerider International has his way, they just may change the world of singlehanded dinghy sailing forever.

Ironically, the Moth class that has spawned the most groundbreaking development in hydrofoil technology is one of the ancient ones. Len Morris built his 11-foot Olive near Melbourne, Australia, in 1928. A year later, Joel Van Sant built a Moth in Elizabeth, New Jersey, to almost the same proportions. In both locations the small catboats were a hit, and numbers grew steadily due to the low cost of building such small, simple dinghies.

The class spread from the U.S. to Europe and from Australia to New Zealand, with huge design variations from fleet to fleet. Various national classes modified their rules slightly to encourage international competition, and with the International Yacht Racing Union’s acceptance of the class in 1972, the International Moth Class was born. The openness of the Class Rule, the first sentence of which reads, “the intention of these class rules is to give the designer and builder the fullest liberty in design and construction,” has resulted in much innovation and a variety of designs, including skiff Moths, pram Moths, scow Moths, skinny tube Moths, dinghy Moths, and now foiling Moths (which can be skiff Moths or scow Moths).

In 1999, Australian Dr. Ian Ward opened a can of worms that would change the class more profoundly than any prior development. Ward fitted horizontal hydrofoils to the bottom of the centerboard and rudder of a Moth and he found that the foils lifted the boat out of the water with ease. Catamaran and trimarans had already proven that three T-shaped foils worked, but conventional wisdom held that a dinghy with two foils would be far too unstable to be sailable. Ward quickly found out that the conventional wisdom was wrong, but devising a system to maintain ride height and control would take more time. Brothers John and Garth Ilett created and refined such a system in 2000 using a surface-sending wand to control the main foil’s lift.

Amidst intense intra-class squabbling, Rohan Veal used the Iletts’ creation to win the 2004 Moth World Championship with eight firsts in eight races. In one race, he beat the second place boat by ten minutes. With non-foiling, or “low riding,” Moths quickly approaching obsolescence, the biggest obstacle to competitive Moth sailors became obtaining their own foiling moths. The Iletts’ Fastacraft and a handful of other small, custom boatbuilders just couldn’t keep up with demand for their carefully constructed, all-carbon dinghies. That’s where McDougall came in.

A longtime Moth sailor, McDougall built his first Moth more than three decades ago. In early 2005, he purchases one of the Iletts’ foiling Moths and immediately knew that it was something special, a sailing experience that shouldn’t be constrained by the limited resources of a few custom builders. McDougall scraped up the money for his own Moth design/build business and set to work improving and simplifying existing designs and components to allow faster fabrication and shorter build times. He spent four months on the design of the foils, performing flow analysis and even writing his own foil-creating software. Once he completed the basic boat design, McDougall recruited Veal to help develop and market the boats, signed a partnership with composite specialist McConaghy Boats, and Bladerider International was born.

There are a handful of foiling Moths in the U.S., but the first two production Bladeriders landed here in April via air freight in boxes weighing about 100 pounds. Detroit sailor Bora Gulari bought the second U.S. boat, and in June he took me out for three days of “flight school.” I came late to sailing and started in big keelboats, so I lack the balance and quick reaction time with which lifelong dinghy sailors are blessed. I weigh around 220 pounds, a third bigger than most competitive Mothies, so in a way, I’m the ideal person to test the Bladerider. McDougall’s vision is not to create one more International Moth, it’s to bring the foiling experience beyond the aerospace engineers and tinkerer/athletes to the average sailor–someone just like me. Twenty minutes on the Bladerider taught me that I’ll never win a Moth World Championship, but I experienced a sensation totally new to me, something that could revolutionize the small boat world.

On the first day, moderate winds on a flat Lake St. Clair provided plenty of power, as Gulari proved less than 20 yards from the entrance to Bayview YC when he launched onto the foils and accelerated to 12 knots, upwind. When he turned down to a reach, our Sea Ray could hardly keep up. After a few minutes, I jumped into the water to take my turn. The first thing that struck me was the boom, in the head. The next was the incredible narrowness of the tiny hull. Dwarfed by large, trampoline-covered carbon wings, the 12-inch wide hull resembles a slab-sided torpedo. The designer realized that the hull would spend most of its time in the air, so he downsized it accordingly. The hull is covered with the most aggressive non-skid I’ve ever encountered, and as tippy as the boat is, that’s a good thing. The racks are works of art: clear-coated carbon sculptures covered with Dacron tramps, their width provides massive righting moment to counter the power from the big, windsurfer-inspired sail that sleeves over a thin-walled carbon mast.

Once I got moving, the instability vanished, even before I lifted free of the water. The foils generate substantial lift and stability at slow speeds, giving the pencil-thin hull the feel of a wide boat. Simple sail controls allowed me to concentrate on placing my body where Gulari told me, although the oversized mainsheet made easing the sail a bit stickier than it should have been. It’s a physical boat that requires lots of balance, and the small loads and efficient controls should be attractive to female and youth sailors.

A puff hit, and I practiced the dinghy mantra, “ease, hike, trim.” Hiking on the wing, I trimmed the sail and lifted almost imperceptibly out of the water. Another puff lifted me completely clear, and things went strangely silent. As a Melges 24 sailor, I’m used to going fast, but that speed is always accompanied by spray, vibration, and the sounds of crashing through waves. Speed on a Moth is completely different–drama free, peaceful, almost trance-inducing. Reality broke into my reverie when I let the boat heel too far to leeward. The boat crashed back into the water, and I hit the shrouds.

For days afterwards, my bruises would remind me of just how fast I’d been going.My test sail was like nothing I’d ever experienced on the water. In twenty minutes, the Bladerider opened my eyes to the possibilities of foilborne sailing. Foils have already invigorated the International Moth Class, with membership growth at a ten-year high, but it’s not just the IMCA that Bladerider is trying to revolutionize. McDougall’s operation currently builds three to four boats per week, but to goal is to double that output.

Priced at $14,000, the Bladerider isn’t cheap, but it provides an utterly new experience. Gliding above the water at double digit speeds, the only sound a faint hiss from the foils, you’ll be transformed. Going back to your loud, sloppy, slow, surface-bound craft might just be unthinkable.

For more about the Bladerider Moth, go to www.bladerider.com.au/

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• Sailboat Guide

Moth (International)

Moth (International) is a 10 ′ 11 ″ / 3.4 m monohull sailboat designed by Open starting in 1928.

Rig and Sails

Auxilary power, accomodations, calculations.

The theoretical maximum speed that a displacement hull can move efficiently through the water is determined by it's waterline length and displacement. It may be unable to reach this speed if the boat is underpowered or heavily loaded, though it may exceed this speed given enough power. Read more.

Classic hull speed formula:

Hull Speed = 1.34 x √LWL

Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio .311 Hull Speed = Max Speed/Length ratio x √LWL

Sail Area / Displacement Ratio

A measure of the power of the sails relative to the weight of the boat. The higher the number, the higher the performance, but the harder the boat will be to handle. This ratio is a "non-dimensional" value that facilitates comparisons between boats of different types and sizes. Read more.

SA/D = SA ÷ (D ÷ 64) 2/3

• SA : Sail area in square feet, derived by adding the mainsail area to 100% of the foretriangle area (the lateral area above the deck between the mast and the forestay).
• D : Displacement in pounds.

Ballast / Displacement Ratio

A measure of the stability of a boat's hull that suggests how well a monohull will stand up to its sails. The ballast displacement ratio indicates how much of the weight of a boat is placed for maximum stability against capsizing and is an indicator of stiffness and resistance to capsize.

Ballast / Displacement * 100

Displacement / Length Ratio

A measure of the weight of the boat relative to it's length at the waterline. The higher a boat’s D/L ratio, the more easily it will carry a load and the more comfortable its motion will be. The lower a boat's ratio is, the less power it takes to drive the boat to its nominal hull speed or beyond. Read more.

D/L = (D ÷ 2240) ÷ (0.01 x LWL)³

• D: Displacement of the boat in pounds.
• LWL: Waterline length in feet

Comfort Ratio

This ratio assess how quickly and abruptly a boat’s hull reacts to waves in a significant seaway, these being the elements of a boat’s motion most likely to cause seasickness. Read more.

Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam 1.33 )

• D: Displacement of the boat in pounds
• LOA: Length overall in feet
• Beam: Width of boat at the widest point in feet

Capsize Screening Formula

This formula attempts to indicate whether a given boat might be too wide and light to readily right itself after being overturned in extreme conditions. Read more.

CSV = Beam ÷ ³√(D / 64)

Single handed development class that has always been at the cutting edge of performance racing dinghies. The MOTH, raced today (2015), at the top tier of competition is a ‘foiler’ with wings.

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And now for something completely different - The International Moth story

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Welcome to the US Moth Class Association

North americans.

The 2024 Moth North American Championship will be held October 18th-20th at Coronado Yacht Club, San Diego, California. NAs will also serve as a springboard event to ship boats to the 2024 Moth Worlds in New Zealand.

. Check out one of the highlight videos from last year's event below and for more, go to Nick Bower's Youtube Channel

Regional Events

 west coast events 2024.

New Years Day Race:  Jan 1, SDYC, San Diego

Winter Series #1: Jan 13-14, MBYC, San Diego

Winter Series #2: Feb 17-18, South Bay, San Diego

Moth PCCs:  Mar 23-24, CYC, San Diego

Long Beach Training Week:  April 7-12, ABYC, Long Beach

Long Beach Spring Classic: April 13-14, ABYC, Long Beach

Ted Rogers Bay Area Championship: May 25-26, RYC, SF Bay Area 

High Sierra Regatta:  Jul 13-14, Huntington Lake

South Bay Summer Classic: Aug 17th, CYC, San Diego

East Coast Events 2024

Summer Regattas in Newport RI, TBD

US Moth Class Newsletter

We send out a handful of US Moth Class newsletters per year to keep class members up to date on events and logistics. Below you can find the 10 most recent newsletters. To subscribe, open one of the links below and click the "subscribe" button on the top left corner of the page

Getting Into the Moth Class

Moth class usa facebook group.

Joining the US Moth Class's Facebook group is the best way to see what's going on and get involved with the class. Stay up to date with regattas, boat building projects, and general moth froth!

Used Boats For Sale

For many people looking to get into moth sailing, a well setup used boat is the best place to start. Check out the Moth Buy & Sell Facebook marketplace to get a feel for what boats are in your price range and feel free to reach out using to the contact us tool at the bottom of this page if you have questions about what to look for when buying a used boat. Keep in mind that international shipping is easy to arrange using out freight partner!

Shipping/Freight Logistics

One of the coolest aspects of the Moth is the fact it can be disassembled and packed into an 11 foot long box for easy shipping! If you're looking to send your boat to a regatta or buy a used boat and need it delivered, shipping is simple thanks to our freight partner, Saturn Freight Systems. They handle everything from regional ground freight to international air freight. Use the contact us tool at the bottom of the page to get put in contact with a Saturn Freight representative.

Interested in learning more about the US Moth Class? Feel free to reach out!

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Death's-head hawk-moth

Death's-head hawk-moth © Lauren Hibbert

Species information

Conservation status, when to see, how to identify, distribution.

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Did you know?

Privet hawk-moth

With a torpedo-shaped body and long, narrow wings, the privet hawk-moth is a striking garden visitor. But the caterpillars really stand…

Lime hawk-moth

The lime hawk-moth is a large, night-flying moth that can be seen from May to July in gardens, parks and woods. It is buff-coloured,…

Hummingbird hawk-moth

The hummingbird hawk-moth migrates to the UK from Southern Europe each year. It can be seen hovering over flowers, feeding with its long…