best antifouling paint for sailboat

Sailboat Bottom Paint: 10 Best Paints

Last Updated by

Daniel Wade

June 15, 2022

If you leave your boat without protection, it's beyond question that it will start attracting several marine organisms such as slime, algae, mussels, barnacle, and seaweed. This will cover the bottom of your sailboat and may negatively affect your boat's speed and fuel efficiency.

This is exactly why you need to apply the best sailboat bottom paint on your boat.

The freedom that sailing and being off land gives you are immense and almost unmatched.

But do you know that having multiple organisms such as algae, slime, barnacle, seaweed, and mussels grow on your boat can throw everything out on the wind and leave you with a very unreliable boat?

These pesky hangers will put a huge dent in your boat's speed, its movement, fuel efficiency, and overall aesthetic.

That's why you need the best sailboat bottom paint to greatly minimize any damage that might be caused to your boat's hull by marine biological growth.

Also known as antifouling paint, bottom paint is essentially a paint or coating that's specifically designed with elements that prevent various marine organisms such as algae, seaweed, barnacles, slime, and mussels from attaching themselves to your boat's hull or any other part of the boat that's below the waterline.

One of the most important elements of bottom paint is the inclusion of a biocide and copper is the most common. This may, however, depend on the type of boat that you have, how, and where you always use it.

But because there's an ocean of bottom paints out there on the market, choosing the best sailboat bottom paint can be an overwhelming task for most of us.

Fortunately, you can always count on us to make it a lot easier for you. We've gone through many bottom paints and we do not doubt that we've selected the most effective, reliable, and best sailboat bottom paint.

Our unbiased selections will not only match your needs and budget but will be available in a variety of colors to complement and augment your boat's visual appeal.

Table of contents

What to Consider when Purchasing Sailboat Bottom Paint

If you're on the market for the best sailboat bottom paint, it's crucial to go for top quality; something that will offer efficiency, top speed, and excellent performance for your sailboat. With that in mind, here are a few things to consider before spending your hard-earned money on bottom paint.

Your Sailing Location

Where are you planning to sail? Is it on a freshwater body or in a saltwater location? This is essential in helping you determine whether to go for a bottom paint that's meant for saltwater, freshwater, or both. It's generally recommended that you go for a bottom paint that will serve you perfectly well in both freshwater and saltwater. This gives you the versatility of sailing anywhere without worrying about marine organisms damaging your boat's hull.

Launch Time and Recoat Time

It's important to keep in mind that bottom paint products have specific launch time limits. The idea here is to ensure that you launch it within the required timeframe and ensure that recoating is done as required. You should, therefore, choose a bottom paint that offers a lengthy launch and recoat time while offering durable protection for your vessel is the right thing to do.

Type of Boat

You should determine whether your boat is made of wood, fiberglass, or aluminum and go for bottom paint that's suitable for that particular surface. Many bottom paints work perfectly with fiberglass but some work great with aluminum or wooden surfaces.

The Fouling Condition

Having a deeper idea of the type of fouling that you might deal with can be crucial when buying the right bottom paint for you. Whether you're dealing with slime, algae, mussel, or any other type of marine organism, knowing the type of fouling you're dealing with will make it a lot easier to pick the best sailboat bottom paint for your vessel.

Best Sailboat Bottom Paint

Rust-oleum marine flat boat bottom antifouling paint.

As one of the most respected brand names in the bottom paint industry, Rust-Oleum is known for producing some of the best sailboat bottom paint and the Marine Flat Boat Bottom Antifouling Paint is one of them. This bottom pain is designed to be suitable for various conditions (both freshwater and saltwater) and is designed with moderate copper that works great if you are environment-conscious.

This bottom paint does an excellent job of offering a protective coating to ensure that your boat is free of all sorts of unwanted marine organisms. You'll love this paint because it is thick and spreads so easily and will not be a problem even if you're a beginner. This bottom paint offers top-notch antifouling properties and is very easy to apply as long as you use a soft brush and mix it carefully. This is a great bottom paint choice that will offer a sleek multi-season finish and ensure that your boat's hull is always awesome and in great condition.

• ‍ Easy and simple to apply
• Great for both freshwater and saltwater
• Offers gentle fouling conditions
• Excellent in antifouling
• Offer a sleek and awesome finish
• ‍ Quite expensive
• Has a very strong smell that can cause headache

Interlux Fiberglass Bottomkote Antifouling Paint

This is another great brand that is considered as one of the best bottom paint in the sailing world. Even though it's a bit pricey, it offers great features that will ensure that your boat remains in tip-top shape. It is an excellent option if you're looking for a sailboat bottom paint that brings to the fore a unique dual resin approach.

This is a very reliable bottom paint that will not only prevent your boat's hull from the effect of marine organisms but also prevent premature deterioration. It offers an awesome polishing action and is perfecting if you want to discard unnecessary paint buildup. This bottom paint is also very economical and a small quantity will cover a considerable surface area of your boat's bottom.

This is, without a doubt, a superb buy in terms of its practicality and economical nature. It is excellently formulated to prevent marine organisms from damaging your boat and also to ensure that premature wear and tear doesn't exist in your vocabulary.

• ‍ It's formulated with a unique dual resin approach to prevent premature wear and tear
• It prevents early decline
• It prevents unnecessary paint buildup
• Great for ensuring that your boat is fuel effective
• Great for all conditions (both freshwater and saltwater)
• ‍ It's expensive
• The quantity and size can be misleading

TotalBoat JD Select Bottom Paint

As one of the few bottom paints that's formulated with low Volatile Organic Compounds (VOC), this bottom paint is one of the most cost-effective on this list. With one gallon, you can easily cover about 400 square feet and the application is a breeze since it's even much easier to clean up.

When you purchase this bottom paint, the package will come complete with a pair of latex gloves, a wooden stir stick, an abrasive pad, a metal tray kit, a paint suit, a roller, a painter's tape, and many more. The inclusion of all these accessories makes it a quite cost-effective purchase.

Again, this is one of the most durable bottom paints. Apply it on your boat's hull and you're guaranteed that it will offer excellent protection for the next 18 months. On the downside, this paint is too thick and you'll have to buy an excellent thinner for it to work perfectly.

Nonetheless, this is an ablative bottom paint that is easy to apply and does an excellent job of protecting your boat's bottom for close to two years.

• ‍ Perfect for all conditions
• Easy to apply and clean up
• Can improve your boat's speed and fuel efficiency
• Comes with all accessories required for the paint job
• It's one of the best water-based bottom paint products in the industry
• It contains low VOC
• ‍ You'll need a top-quality thinner for it to work perfectly

Aquaguard Water-based Antifouling Bottom Paint

An excellent choice for both wooden and fiberglass boats, this is the most perfect bottom point for saltwater conditions. This is a water-based bottom paint that's very easy to apply and clean up (using soap and water) and is formulated with an ablative action that makes it superb for preventing any marine organism that may negatively affect your boat.

This is a bottom paint that is EPA-approved and surpasses the set VOC standards. It has an extended shelf life and offers durable protection for your sailboat. It doesn't contain toxic fumes and is great even for novices. Its drying time is also excellent, so you won't wait for far too long to get your boat out there on the water.

• ‍ Excellent for saltwater conditions
• Application and cleaning is very easy
• It's approved by the US EPA
• You don't have to use a primer
• ‍ The color selection is limited
• A bit pricey

Pettit Hydrocoat

This is another water-based bottom paint that offers outstanding ablative properties that will protect your boat from marine organisms throughout the seasons. It offers good value for money and is easy to apply and clean up with just water and soap.

We're talking about a bottom paint product that will protect your boat's hull for months on end. You also do not need a full tank of the paint to complete the job. With just a single gallon, you can be sure to complete an area as big as 430 square feet.

This is also one of the few bottom paints that can perfectly prevent your boat from damage when being trailered, launched, or beached. More importantly, it's not irritating to the nose and eyes because it has low VOC.

• ‍ It will dry in 3 hours
• It's easy to apply and clean up
• It offers multi-season protection
• It's not irritating to the eyes and nose
• It's quite economical
• ‍ May not be the best in antifouling
• You have to apply at least two coats

SEA HAWK PAINTS Aluminum Boat Paint

One of the best aluminum boat paints in the market, this bottom paint is formulated to offer quick-dry corrosion-blocking, high-solid features. This bottom paint is specifically manufactured to be used in aluminum boats and doesn't require the addition of any primer.

While it doesn't have an antifouling feature, it stands out and can be used both below and above the waterline as it is risk-free and free or chromate. It is also formulated to offer a unique dual resin approach and can be used both as paint and a primer at the same time.

This is a great paint for both freshwater and saltwater conditions and can be applied as a primer or topcoat on a fiberglass boat. This is an excellent sailboat boat bottom paint that's worth every coin as it is practical, versatile, and can combat both rusting and lifting.

• ‍ The application and cleanup process is easy
• Great for both freshwater and saltwater conditions
• It doesn't require a primer
• Can be used as primer or topcoat in fiberglass boats
• Can prevent rusting and lifting
• It has quick-dry and anti-corrosion features
• ‍ Can produce deadly fumes

TotalBoat Spartan Boat Bottom Paint

If you've been looking for a practical, reliable, and cost-effecting bottom paint that will offer durable performance and protection, the Spartan Boat Bottom Paint. Perfect for both freshwater and saltwater, it can be perfect for protecting your boat and ensuring that it is fuel-efficient and reliable.

This bottom paint is formulated with advanced copolymer ablative to ensure that it doesn't deteriorate instantly. This is a very dependable bottom paint that will serve you perfectly throughout the year and will ensure that your boat easily defies fouling while reducing unnecessary buildup and sanding on your boat.

This is a very adaptable bottom paint that not only offers great value for money but is very easy to apply. More importantly, it is very durable and will protect your vessel for at least 12 months on any type of water.

• ‍ Great for all types of water
• It offers a very durable protection
• Available in a wide variety of color selection
• Offer a visually appealing abrasion-proof finish
• ‍ The included accessories aren't up to the right quality

To this end, we must put a lot of emphasis on the importance of having the right bottom paint for your boat. In addition to being an antifouling agent, bottom paint will significantly increase the fuel efficiency of your boat and ensure that it performs optimally at all times. Of course, you do not want to diminish your sailing escapades or have your nice and beautiful vessel damaged by marine organisms just because you didn't apply the right sailboat bottom paint. If you're unsure how to proceed, here's how to paint a sailboat.

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Home » Blog » Sail » Boat bottom paint: choose the best antifouling paint for your boat

Boat bottom paint: choose the best antifouling paint for your boat

By Author Fiona McGlynn

Posted on Last updated: February 9, 2022

You’re perusing the chandlery looking for a gallon of boat bottom paint (a.k.a antifouling paint). You just want to get in, get out, and get on with painting your boat.

But you reach the paint aisle and are awash in choices and confounding terms : hard modified epoxy, premium ablative, water-based, photoactive, thin film … The shop assistant suggests one paint, but your marina neighbor swears by another brand.

You’re feeling defeated. What happened to the good old days of slapping on some tar with a paintbrush and calling it a day?

Welcome to the convoluted (and at times highly controversial) world of marine boat bottom paint!

Fortunately, antifouling paint is not all that complicated . We’ll walk you through the different types of paint, help you choose the right bottom paint for your boat, and list the best boat bottom paint brands in each category.

Note: This post contains affiliate links. If you purchase a product through a link on this site we will earn a small commission. All opinions are our own. Thanks for your support!

What is boat bottom paint?

Antifouling paint is a specialized paint that is applied below the waterline to inhibit the growth of weeds, slime, and animals (e.g., barnacles and tube worms).

All antifouling paints are made from a combination of these four components:

• Biocide (deters living organisms)
• Resin (keeps the paint together)
• Solvent (determines application characteristics and clean up/removal methods)
• Pigment (color and viscosity)

The differences in paints are based on the sources and mixes of these four elements .

For example, the softness or hardness of a paint is determined by the type, combination, and quantity of resin used in the mix. More on the differences between soft and hard paints later!

Do I need bottom paint on my boat?

For boats kept in the water for more than a week at a time, it is necessary to apply boat bottom paint to prevent growth of marine life (fouling).

Why would you bottom paint a boat?

Boat owners apply antifouling paint to the bottom of boats that are left in the water all season because it reduces the growth of marine life (fouling). Fouling not only reduces a boat’s performance but can also permanently damage the hull.

• Fouling can dramatically reduce a boat’s performance. A fouled bottom causes drag, which reduces fuel efficiency, speed, and handling, and can even cause a boat to sit lower in the water.
• Fouling can permanently damage the hull. In extreme cases, where marine growth has been left unchecked for extended periods of time, the “glue” produced by fouling critters can damage fiberglass and wooden boats.

How long does bottom paint last on a boat?

Depending on the marine life in your area, how you use your boat, and how often you clean your hull, you may need to apply antifouling paint anywhere from once a year to once every three years .

When should you bottom paint a boat?

Bottom paint may last one to three years, but you should check to see if it needs new paint, every year. If you see worn-through patches, flaking, blistering, corrosion, or any of the signs below, it’s time to repaint. Clean the bottom of your boat first, so you can see the condition of the paint.

• The paint has worn through. A common practice is to alternate boat bottom paint colors so you can clearly see when this has happened. • Flaking or blistering paint. When water gets under the paint (often around hardware) it can cause blistering and damage. If you see a fair bit of flaking or blistering, it’s time to repaint. • If you find yourself using abrasive tools and scrubbing to remove growth while cleaning your hull. Your dive service can also advise you on when it’s time for new paint. • If you notice performance issues , like reduced boat speed or handling and you have persistent growth on the hull. • Corrosion (if you have an aluminum boat). Aluminum doesn’t “rust”, though it does produce aluminum oxide which causes paint to flake off, exposing the aluminum underneath. • Your boat has been stored in the water for three seasons . Despite manufacturer claims to the contrary, most paint jobs don’t last more than three seasons.

A note on timing and temperature

Most boaters apply antifouling paint at the beginning of the season once temperatures have warmed up enough for the paint to dry. It’s important to know that paint will only dry under the right conditions (generally speaking 50-85 degrees F and below 65% humidity). It can be too cold, hot, or humid for the paint to cure, so read the manufacturer’s directions and choose your timing carefully.

Note that hard boat bottom paints lose their antifouling effectiveness when exposed to air so you would not want to apply hard paint in the winter and then store it out of the water for several months.

Types of boat bottom paint

Antifouling paints can generally be classified into three groups: s oft paints , hard paints , and hybrid paints. As mentioned previously, the difference between soft and hard paint is the type, combination, and quantity of resin used in the mix.

Ablative bottom paint

Soft bottom paint (a.k.a. self-polishing and ablative bottom paint) is intended to gradually wear away as water flows over the hull. As the paint gradually sloughs off, it exposes fresh biocide, preventing marine organisms from attaching to the hull.

• Reduces buildup of old paint (as it’s constantly wearing away) which means less sanding and expense when you go to repaint.
• Soft paints contain less copper but the ablating action means the copper is used more efficiently.
• Does not lose effectiveness when exposed to air.
• If the boat is docked for long periods (not moving) the paint will not effectively slough off and fouling will occur.
• Ablative antifouling paints are a poor choice for fast boats because higher speeds quickly wear away the paint.

Generally recommended for:

• Slow boats (e.g. cruising sailboats and non-planing powerboats) that are used frequently as well as boats that are stored out of the water for part of the year. While displacement boats may choose either soft or hard bottom paints, many boat owners opt for soft paints due to the advantages of lack of paint build-up.

Interlux’s Micron CSC

Pettit’s ultima sr40.

Hard bottom paint

Hard bottom paint ( a.k.a non-sloughing or hard modified epoxy paint) does not erode over time and instead, the  biocide leaches into the water. Water will gradually penetrate the paint until the biocide has been completely used up at which point the hard paint is no longer effective.

• Great for fast boats (e.g. racing sailboats and powerboats) as their tough exterior does not erode with increased speeds .
• Can be “burnished ” (finely sanded and polished) to provide a fast and smooth surface .
• Often contain a higher copper content which means better antifouling performance.
• Can be scrubbed more aggressively than ablative paint when cleaning the bottom of your boat.
• Hard paints build up over time with each additional coat unless vigorously sanded back each year. Eventually, the paint may build to a point where it cracks and peels and the hull will need to be stripped back (a very time-consuming process).

Stripping back paint to gel coat is a multiweek paint job and one of the downsides to hard paints which build up over time.

• Fast boats (e.g. racing sailboats or planing powerboats) and boats that stay in the water year-round. Ablative paints won’t last long at high speeds and a hard burnished surface will be faster for racers.

Interlux’s Ultra

Pettit’s trinidad sr.

Hybrid bottom paint

Hybrid bottom paints (aka semi-hard ablative paints) incorporate many of the benefits of both hard and soft bottom paints into a single product. Hybrid paints are self-polishing (like soft paint) and release biocides at a controlled rate (like a hard bottom paint), but they can’t be burnished to a smooth slippery surface for smoothness and speed. They also have less buildup than a hard paint.

• Ablative action
• Releases biocides
• Less buildup than hard bottom paint
• Holds up to faster speeds
• Can tolerate haulouts and air exposure without loss of protection
• Can’t be burnished

Generally recommended for

• Highspeed powerboats
• Slower displacement boats
• A fast trailerable boat may be better off with no paint at all as hard paints don’t do well when exposed to air for long periods . If that’s not possible, a hybrid paint may be a better option.

Things to consider before buying bottom paint

There are a few important things you should consider when choosing a boat bottom paint.

What type of material is my boat’s hull?

Boat hulls can be wood, fiberglass, aluminum, and steel. It’s important to ensure that a paint is appropriate for your boat’s hull material.

For example, aluminum boats must use specialized aluminum-safe paint. The cuprous oxide in regular paints will result in galvanic corrosion and damage an aluminum hull. Aluminum-safe paints use alternate biocides like zinc and cuprous thiocyanate.

For the same reason, you should never paint underwater metal components (like a propeller) with cuprous oxide paints .

Examples of aluminum safe paints: • Interlux’s Pacifica • Pettit’s Ultima Eco

What type of paint is on my boat right now?

If you’re repainting a boat you must ensure that any paint you apply is compatible with the existing paint on the hull. West Marine , Pettit , and Interlux all publish compatibility charts for reference .

As a rule of thumb, soft paints can be applied over hard paints but hard paints cannot be applied over ablative paints . To switch from soft paint to hard paint, the soft paint should first be entirely removed.

But what if I don’t know what the old paint on the hull is?

If you don’t know what type of bottom paint is currently on the hull, you can at least determine whether it is hard or soft paint by rubbing the hull with a light-colored, damp rag. If the paint easily rubs off onto the rag, it’s likely ablative.

How often do I use my boat?

If you use your boat frequently, ablative bottom paint is a good choice because fresh biocide will be released as the boat moves through the water.

If your boat will be sitting for long periods, a hard bottom paint may be a better choice.

Where will I be using my boat?

There are many different types of fouling. Marine biologists estimate there are more than 4,000 known fouling species! Generally, these species fall into one of three groups: animals, weeds, and slime.

Factors like water temperature, water quality, nearby population centers, inflows from rivers and streams, the speed of currents, and the amount of sunlight will affect the types and degrees of fouling in your area.

You’ll want to choose a bottom paint that is suitable for the fouling in your area. As fouling can differ from one marina to the next, it’s a good idea to ask the dockmaster or boaters in your marina what fouling they notice and what paint they use.

For example, freshwater areas like the Great Lakes, don’t have to worry about barnacles, but they do suffer from slime. In this case, a thin film paint might be a good option as it offers a super slippery, low friction finish to prevent slime from attaching to the hull.

Examples of thin film paints:

Interlux’s vc offshore, pettit’s sr-21, do i plan on racing my boat.

If you’re looking for high-performance, opt for a hard bottom paint that can be burnished (wet sanded) to a shiny, slippery, and fast finish.

What are the environmental regulations in my area?

The word “biocide” literally means “life-killer”. The biocides used in anti-fouling paint are harmful to aquatic life (and not particularly healthy for humans to work with). It’s widely accepted that accumulated copper from boat bottom paint is detrimental to the marine environment .

In places like California and Washington state, this has led to new environmental regulations regarding the sale and use of boat bottom paints. Many locales also limit copper accumulation by prohibiting in-the-water hull cleaning.

In response to these health risks and environmental concerns, paint manufacturers have begun to offer more environmentally friendly alternatives, including:

• Water-based, low volatile organic compound (VOC) bottom paints
• Copper-free bottom paints containing photoactive materials and organic biocides.  

These non-toxic, copper-free, and environmentally responsible alternatives to conventional antifouling paints are effective, kinder to the environment, and healthier for the person using them.

Examples of eco-friendlier bottom paints:

Interlux’s micron cf, pettit’s hydrocoat eco.

How many coats of bottom paint do I need?

For ablative paint , a single coat is sufficient for a season, whereas two or three coats of paint are recommended for multi-season use.

For hard paint , one or two coats is generally recommended. Additional coats will just add to more sanding down the road.

If in doubt, check the manufacturer’s recommendations.

How many gallons of bottom paint do I need?

The amount of bottom paint you’ll need depends on the size of your boat and how many coats you apply.

You can use this calculation to give you a rough estimate of how many gallons of paint you’ll need per coat.

Calculate the area you’ll need to paint:

[Length of your hull LOA (in feet) x Beam (in feet) x .85]

Then, divide it by the paint coverage listed by the manufacturer.

Area to paint (in square feet) / coverage (in square feet per gallon)

For example, a 35-foot sailboat with a 12-foot beam using a paint with a coverage of 400 square feet per gallon would be:

[35 x 12 x .85] / 400 = .9 gallons per coat

With this information in hand, you can now walk confidently into your local chandlery and make an informed decision on antifouling paint. It’s time to paint!

Fiona McGlynn is an award-winning boating writer who created Waterborne as a place to learn about living aboard and traveling the world by sailboat. She has written for boating magazines including BoatUS, SAIL, Cruising World, and Good Old Boat. She’s also a contributing editor at Good Old Boat and BoatUS Magazine. In 2017, Fiona and her husband completed a 3-year, 13,000-mile voyage from Vancouver to Mexico to Australia on their 35-foot sailboat.

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Which Bottom Paint Should I Use?

What is Boat Bottom Paint?

Bottom paint is applied below the waterline on your boat, and typically refers to antifouling paint that prevents marine growth from clinging to your hull. Barnacles and slime can slow you down and increase your fuel costs because the engine has to work harder to move your boat through the water. A bottom full of barnacles and weeds can also put you in harm’s way because it can seriously hamper your ability to maneuver.

The key antifouling ingredient is some type of biocide for deterring hard marine growth such as barnacles and mussels. Some antifouling paints also include an algaecide for preventing soft growth like algae, slime and weeds. There are many different antifouling coatings, making it hard to choose the paint that’s right for your boat and your budget. Some coatings work better in different locations, including fresh or salt water. Some are more environmentally friendly than others, and some cost more based on the amount and type of biocide, and the protection they provide.

Do I Need Bottom Paint on My Boat?

If you pull your boat out of the water every time you use it, you probably don’t need bottom paint. But if you keep your boat in the water all season, or if you take your boat out of the water periodically, such as on a trailer or lift, then yes, you should apply bottom paint to prevent hull fouling. Same goes whether you keep your boat in salt water or fresh water.

What are the Different Types of Antifouling Paints?

All bottom paints are not the same and will not be effective for all boats, in all waters and fouling conditions, and for all types of boating. Bottom paints are usually one of two types: hard or ablative, with variations that are effective based on how much time the boat spends in the water and how often it moves. For example, hard bottom paints are effective for a single season, and they build up season after season, eventually requiring costly removal. Ablative paints come in single-season and multi-season varieties and don’t build up.

Ablative Bottom Paint

Ablative paint is designed to gradually wear away as water flows beneath the hull, either from use or from the movement of tides and currents. Fresh biocide is exposed as the paint layers wear away, preventing marine fouling organisms from attaching to the surface. Some ablative paint formulas are for multi-season use, and some are effective for only a single season. Also, ablative bottom paint can be copper-based or copper-free, and water-based or solvent-based. For most ablative paints to work effectively, motion is required, so this paint is best if you use your gets frequent use.

Self-Polishing Copolymer Ablative Bottom Paint

This type of antifouling paint also wears away gradually to expose fresh layers of biocide, but the self-polishing properties of its controlled-release copper copolymer formula make it work whether the boat is at anchor or underway. Some copolymer ablatives are effective for multiple seasons, and need only a light scuffing to reactivate the antifouling in the spring, just before launching.

Hybrid Copolymer Ablative Bottom Paint

Hybrid bottom paints are self-polishing and release biocides at a controlled rate like copolymer bottom paints do, but hybrid paints can be burnished–like a hard bottom paint–for smoothness and speed. Unlike hard bottom paints, hybrid paints have less buildup to remove next season.

Hard Bottom Paint

A hard bottom paint coating doesn’t wear away like an ablative coating does, it just loses its biocide over time. The biocide in hard bottom paints leaches constantly while the boat is in the water, whether the boat is moving or not. Hard paints lose their effectiveness once all the biocide leaches out. Because hard bottom paint doesn’t wear away, it builds up and has to be sanded down before reapplying bottom paint the next season. Also, hard bottom paints generally become rendered inactive one the boat is hauled out of the water, so they’re best for boats that remain in the water for extended periods. They’re also ideal for racing boats or boats operated at faster speeds because the hard paint coating can be burnished to increase smoothness and speed.

Questions to Answer Before Buying Bottom Paint

What is my boat made of.

When it comes to choosing bottom paint, substrate (surface) is a big consideration. Do you have an aluminum, fiberglass, steel or wooden boat? Most bottom paints contain some type of copper biocide, which is suitable for fiberglass and wooden boats, but not for aluminum. The copper in the paint causes galvanic corrosion, which will destroy an aluminum boat or pontoon boat. For antifouling protection on aluminum boats and underwater metal parts, you have to apply a copper-free bottom paint .

Inflatable boats made of PVC, Hypalon or other materials also need bottom paint if they’re left in the water for long periods. Ablative bottom paints designed for inflatable boats won’t crack after drying or peel while you’re rolling up the inflatable for storage.

Where Do I Use or Keep My Boat? Location is Everything!

What are the fouling conditions in your area? By ‘area’ we mean not only the geographic location, but the specific harbor, and even your location in the harbor. Why? Because the fouling conditions can be that location-specific. Is the fouling light, moderate, or heavy in your part of the harbor? Typically, more biofouling occurs in waters that are warm and still, rather than colder waters where water flow is unrestricted.

Is My Boat in Fresh Water or Salt Water?

Barnacles, algae and slime are the bane of boat owners who do their boating in salt water. And even though boats left in freshwater don’t have to worry about barnacles, they can still get slimy and grow green beards. If algae slime and algae are a problem, you’ll want a paint that contains an algaecide such as zinc pyrithione (this applies to copper-free biocides, too). If you do your boating in freshwater lakes, look for bottom paints designed specifically for freshwater fouling. Why pay for extra protection you don’t need?

How Often Do I Use My Boat?

If you use your sailboat or power boat frequently, ablative bottom paint is a great choice because it’s most effective when the boat moves through the water to release fresh biocide. If you don’t use your boat as often and it spends a lot of time at the doc or on the mooring, your best bet would be a self-polishing copolymer paint that’s effective whether the boat is moving or not. In addition, brief boating seasons are suitable for a single-season antifouling paint , but for a longer boating season, it can be more effective and economical to apply a multi-season bottom paint . If you trailer your boat, a harder ablative antifouling paint that can withstand trailering and beaching might be the way to go.

Do I Want to Use My Boat for Racing?

If you want to race your boat or you just want to make your boat go faster, use a thin film bottom paint, a hard modified epoxy bottom paint, or a hybrid bottom paint that can be burnished. Burnishing involves wet sanding or using a Scotch-Brite® pad to make the surface smoother.

Should I Use Solvent-Based Bottom Paint or Water-Based Bottom Paint?

Environmental restrictions in some areas prohibit the use of solvent-based paints due to their high VOC (volatile organic compound) content. If this is the case, you can apply a water-based, low VOC bottom paint . Water-based bottom paint offers easy cleanup and is very effective against marine fouling.

A common misconception about water-based bottom paint is that it will dissolve and leave the hull with no antifouling protection once the boat is in the water. Not true. Once cured, the water in water-based bottom paint evaporates and leaves a protective film containing the biocide.

Should I Use Copper-Based or Copper-Free Bottom Paint?

Again, environmental restrictions may dictate the use of copper-free antifouling bottom paint. Typically, a higher percentage of copper in the paint means it’ll be more effective at combating shell fouling. But copper-free bottom paint containing the eco-friendly biocide Econea™ (tralopyril) has proven very effective on shell fouling such as acorn barnacles and zebra mussels. If you have an aluminum boat, you have to use a copper-free antifouling paint to avoid galvanic corrosion, which will destroy aluminum. Underwater metals also need bottom paint that’s copper free .

What Type of Bottom Paint is on My Boat Now?

If there’s bottom paint on your boat now, it’s really important that your new bottom paint is compatible with the old bottom paint. You don’t want your new paint to peel, so you need to find out what the previous paint is. If you can’t determine that, you’ll need to strip off the old paint completely and start over. Antifouling paint formulas change often, but here are some general compatibility and surface preparation guidelines. For best results, read the bottom paint manufacturer’s recommendations.

How Much Do I Want to Spend On Bottom Paint?

Typically, the higher concentration of biocide a bottom paint has, the more expensive it will be. Hard bottom paints are typically less expensive than ablative antifouling paints. Among the ablative marine paints, the single-season ablatives are typically less expensive than the multiple season ablatives.

How Much Bottom Paint Do I Need?

The amount of bottom paint varies depending on how big your boat is and how heavily you apply the bottom paint. Refer to the paint manufacturer’s details on coverage amounts (typically given in square feet per gallon). Here’s an easy formula for figuring out the square footage of your hull below the waterline, where you’ll be applying bottom paint.

Length (in feet) x Beam (in feet) x .75 Here are some typical estimates for various types of boats. These estimates assume you’re applying two coats, and that you’ll be coating the surface as thickly as possible without drips or runs.

How Often Should I Bottom Paint My Boat?

How long does boat bottom paint last? Depends on the type of bottom paint you use and your boating conditions. Typically, you should apply bottom every year, but there are some bottom paints that last multiple seasons. If you use your boat regularly or keep it in the water, check it every year to see if you need to reapply bottom paint.

Hints to Help You Choose the Right Bottom Paint for Your Boat

• Ask other boaters in your local marina – they’re a prime source of information about what works and what doesn’t in your particular location.
• If you want to paint in the fall and launch in spring without repainting, choose a multi-season self-polishing copolymer paint . This type of bottom paint has an unlimited launch window.
• All bottom paint manufacturers have a chart that shows the compatibility of their bottom paints with those of existing brands. Be sure to take a look at the compatibility chart before you buy.

TotalBoat Bottom Paint Comparison Chart

* Krypton provides full-season protection in salt water, where the water flow is unrestricted. It can provide multi-season protection in fresh water conditions. If you have any questions about which bottom paint to use, please call our Tech Support Team at (800) 497-0010.

Krypton Copper-Free Antifouling Bottom Paint

JD Select Water-Based Bottom Paint

Underdog Boat Bottom Paint

TotalProtect Epoxy Barrier Coat Primer

TotalFair Epoxy Fairing Compound

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The Ultimate Detailed Antifouling Boat Bottom Paint Guide

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What to Look for In Boat Bottom Paint

• By Pete McDonald
• Updated: April 24, 2020

So you’re looking to protect your boat’s bottom from biological growth, known as fouling. (We’d have to assume so, otherwise why are you reading an article about paint?) Basically, in selecting bottom paint for your boat, you have to ask yourself the following questions, at a minimum. In what part of the country are you doing your boating? Do you haul your boat for the winter or leave it in year-round? Does your boat already have an old coat of bottom paint or are you starting from scratch? Depending on how you answer each of these questions, there’s an anti-fouling bottom paint that’s right for you.

Bottom paint works by releasing a small amount of biocide over time that keeps any algae, plants or animals from adhering to the hull. Usually, but not always, this is accomplished with a metal-based biocide, most commonly copper, but where you live and how you boat will determine what you should use as much as anything. (Washington had passed a ban but has since lifted the restriction.) Beyond that, you will likely be choosing between a single or multi-season “ablative” paint or a hard modified-epoxy paint. With ablative paint, the entire application will wear down over time, while the hard paint will retain its thickness as it sheds biocide. Multi-season ablative paints will still work if you pull a boat for winter storage and relaunch it next season, while single-season ablatives need to be applied every year. Modified-epoxy paints lose their effectiveness when pulled from the water for any length of time.

Do you boat in salt water or fresh? Paints designed to prevent barnacles in salt water might not be effective in preventing freshwater algae or slime growth, or in deterring zebra mussels. If you boat in the Great Lakes or other freshwater areas where slime is a problem, consider a paint that contains an agent called Irgorol 1051, which works to block photosynthesis in algae and other plant-based hitchhikers. Check out Petit Trinidad SR Antifouling Paint with Irgirol or Interlux Mircon CF with Slime Blocking Technology (not Irgorol but a different agent).

If you boat in salt water, a paint like Interlux Micron 66, which uses a copper-based cuprous-oxide biocide as well as slime-controlling Biolux, is an excellent choice for deterring barnacle growth. Or choose one of Interlux’s Micron CF (Copper Free) paint to do the job.

If you haul your boat in the offseason, you’re going to want to use an ablative paint that will retain its effectiveness if left out of the water for long stretches and relaunched, such as Pettit’s Odyssey HD. If you keep your boat in the water year-round, particularly if you live in areas with heavy fouling issues, look for a hard bottom paint with a higher biocide concentration, such as Petit Trinidad HD or Interlux Ultra with Biolux.

Repeat Performance

If your boat already has bottom paint, it’s best to go with the same type of paint when it’s time to reapply. Some soft ablatives will work over hard modified epoxies, but check with the paint company for compatibility. If worse comes to worse, you’ll have to sand off the entire old coat and start the process again. Fortunately, we have an article to help guide you through it. Go to boatingmag.com/recoat .

Copper Free

For people who want to use an alternative to heavy metals, consider a copper-free paint such as Pettit ECO HRT, which works on fiberglass and aluminum hulls, or Interlux Pacifica Plus, an ablative paint that uses the more environmentally friendly Econea to fight barnacles as well as Biolux to combat slime. Both Pettit and Interlux also offer of water-based products, as opposed to the solvent-based “norm” of anti-fouling coatings. Finally, copper-free paints can safely be applied to underwater metals.

Read Next: Prepping Your Boat for Bottom Paint

Specialty Antifouling

Some paints, like Interlux VC Offshore, can enhance speed and efficiency. These provide a super smooth, or super slick finish and can often be polished, (“burnished.”) to a fine sheen for delivering utmost efficiency. And, while most antifoulants are dull, some can provide bright colors, like Interlux Vivid. Still other formulations are best for protecting underwater metals. These are usually copper-free to prevent creating a galvanic circuit with aluminum.

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Your Ultimate Boating Resource

Antifouling Paints: A Guide to Keeping Your Boat Shipshape

If you own a boat, you’ve likely heard of “fouling,” which refers to the accumulation of unwanted growth, like algae, barnacles, and other marine organisms on its hull below the waterline. This build-up not only makes your boat look unsightly but can also affect its performance, fuel efficiency, speed, and, in extreme cases, even cause damage to the vessel. Anti-fouling paints, which actively prevent or slow down this process, help keep your boat clean and in top shape. This article will introduce you to anti-fouling paints, explain how they work and provide guidelines for selecting and applying the right one for your boat.

The Importance of Anti-fouling Paints

Fouling can lead to various problems for your vessel. Some of these issues include:

1. Reduced performance : Bio-fouling increases drag, making it more difficult for your boat to move through the water. As a result, your boat’s top speed is reduced, and it may take longer to reach your destination.

2. Increased fuel consumption : Bio-fouling can also affect fuel efficiency. Increased drag forces the engine to consume more fuel to maintain speed, leading to higher operating costs.

3. Structural damage : Marine organisms can damage the hull’s material by burrowing into it or corroding its protective layer, leading to costly repairs.

4. Environmental impact : Many invasive marine organisms travel by attaching to the hulls of ships and boats. Anti-fouling paint can help prevent the transfer of these species from one body of water to another.

Given these risks, it makes sense to use anti-fouling paints to protect your boat, save money, and preserve the marine environment.

Types of Anti-fouling Paints

There are two primary types of anti-fouling paints: hard and self-polishing copolymer (SPC).

Hard Anti-fouling Paints

Hard anti-fouling paints, also known as contact leaching paints, create a tough, durable coating on the boat’s hull. They release chemicals or biocides at a controlled rate to deter marine growth.

• Long-lasting and durable
• Can be sanded or burnished for racing or high-performance applications
• Withstands extended periods out of the water when the boat is in dry dock or on a trailer
• Can lose effectiveness over time as the chemicals are depleted
• May require more frequent application due to their constant biocide release

Self-Polishing Copolymer (SPC) Anti-fouling Paints

SPC paints provide a smoother finish than hard paints, and their biocides are released more slowly. These paints have a chemical structure that allows them to wear away gradually, exposing fresh layers of biocide-loaded paint beneath.

• Consistently smooth hull finish
• Extended longevity due to controlled biocide release
• Improved fuel efficiency and performance as fouling is effectively reduced
• Less durable than hard paints, and not suitable for boats that spend extended periods out of water
• More expensive than hard anti-fouling paints

Selecting the Right Anti-fouling Paint for Your Boat

When choosing an anti-fouling paint, consider the following factors:

1. Type of boat : Different boat types, such as sailboats, powerboats, or racing boats, may require specific anti-fouling paint formulations. Check the manufacturer’s recommendations for your specific boat type.

2. Water type : Saltwater and freshwater have different fouling organisms, necessitating different paint formulations. Pure freshwater boats may require different anti-fouling paint than those operating in saltwater or brackish environments.

3. Boat usage pattern : Consider how frequently you use your boat and how long it spends in and out of the water. If your boat typically stays in the water for extended periods, SPC paints may be a better choice due to their controlled biocide release.

4. Local regulations : Some areas have specific regulations regarding anti-fouling paints, primarily concerning copper-based biocides. Be sure to familiarize yourself with these regulations and choose a paint that complies with them.

Applying Anti-fouling Paint

Before applying anti-fouling paint, prepare the surface of your boat’s hull by removing any existing anti-fouling paint and other contaminants. Once the surface is clean and smooth, follow these steps:

1. Apply a primer coat: A primer helps the anti-fouling paint adhere better to your boat’s hull. Choose a primer that is compatible with your chosen anti-fouling paint and apply as per the manufacturer’s instructions.

2. Apply the anti-fouling paint: Mix the paint thoroughly and apply it to the cleaned and primed surface using a roller or brush. Apply at least two coats, allowing each coat to dry before applying the next. Follow the manufacturer’s guidelines for drying and over coating times.

3. Allow the paint to cure: Give the paint ample time to cure according to the manufacturer’s recommendations before launching your boat.

By selecting and applying the right anti-fouling paint, you can protect your boat from unwanted marine growth and ensure optimal performance, fuel efficiency, and longevity.

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• Repainting the Boat

The Best Antifouling Paints Tested and Compared

Applying antifoul to the underwater hull of your boat is necessary to keep organisms away that could slow it down or cause it to erode. But which antifouling paints really offer reliable protection? Which is the best antifoul? And how do various antifouling products perform when tested and compared directly? Find answers to these questions in this test and comparison guide to antifouling . It also includes important information about the costs of various antifouling products .

• Which antifouling is the best?

Antifouling paints in comparison

• Comparison: Biocide-free and self-polishing antifouling
• Comparison: Hard and thin film antifouling
• Antifouling test
• Antifouling cost

The great SVB antifoul comparison Biocide-free and self-polishing antifouling in comparison

Self-polishing antifouling 2024.

Note: Comparing antifoulings directly can be difficult, as even small changes in the boat and the environment can have an influence on possible fouling.

For this reason, in this antifouling comparison, self-polishing antifoulings and biocide-free antifoulings are compared with each other, as are hard antifouling and thin-layer antifoulings . The reason for this is that these types of antifouling work in different ways. Self-polishing antifouling gradually wears off by itself, releasing biocides and thus protecting your boat from fouling. Hard antifouling forms a hard surface that gradually releases bioactive substances to protect against fouling. And thin film antifouling protects your boat from organisms attaching by providing a very smooth surface. This antifouling comparison guide does not compare specific antifouling applications, such as for propeller & sterndrive.

Hard & Thin Film Antifouling Comparison

Hard antifouling is best used on faster boats, such as motor yachts.

Hard & Thin Film Antifouling 2024

I am very happy with Seatec antifouling. Nice priceperformance ratio.

I have used this for years. It discolours at the waterline so I use Trilux which does not , a bit below the waterline up to the cove line. The trilux needs sanded off each year, the VC does not.

Which is the best antifoul?

There is no "best" antifouling that can be used on all boats. Different types of antifouling are more effective depending on the boat itself and where it is sailing. It's also important to know which previous antifouling was used. More information can be found in our guides "How to find and apply the right antifouling" and "How to properly remove antifouling" . In our online shop you will find the best antifouling paints from the brands Seatec, International, Hempel, Boero, Epifanes, Tikal, Yachticon, Jotun and Yachtcare, which are suitable for a wide range of boat and area requirements. Discover SVB's best antifouling for your underwater hull!

We have compared the 10 best antifoulings from the brands International, Seatec, Hempel, Epifanes and Boero.

How do we compare our antifouling paints?

For the best comparison and test results of our products, various factors are taken into account in the evaluations. This includes the features of the respective product, the many years of experience of our SVB experts as well as our customer comments and reviews.

Our assessment categories

• Comparison winner: The product with the best overall result, regardless of price.
• Price-performance winner: The product that gives the best value for money. Good quality at a reasonable price.
• Best-seller: The top seller that is currently our most popular.
• Green aspect: Biocide-free

Antifoulings in practice

The magazine "Boote" carried out an antifouling test for the 3/2017 issue , in which various antifouling paints were tested in practice.

The test focussed on the difference in fouling protection given by cheaper and branded products. For the test, five antifouling products from Hempel, International, Nautical, Epifanes and Yachtcare were applied to a ship in sections at the beginning of the 2016 season. In order to test the anti-fouling protection, the boat was placed in the port of Hamburg-Tatenburg and sailed to various fresh, salt and brackish water regions during the year. At the end of the season, the vessel was taken out of the water and the amount of fouling compared on the different areas.

The test revealed that all antifouling products did their job well. However, antifouling paints from International and Hempel provided the best protection. . It was easy to wipe off the small amount of fouling that had developed there. Hempel Hard Racing excelled with its very smooth surface. The price differences between the antifouling paints in the test were quite significant. Antifouling test winners at the time were more expensive brand-name products. Nevertheless, the somewhat cheaper products such as those from Yachtcare also performed very well in the test.

In Boote's test, antifouling paints for warm and nutrient-rich waters were also looked at. In these kinds of waters, boaters should choose products that are most effective, in order to protect the underwater hull in the best possible way. Hempel and International antifouling paints were the best at the time of the test.

Biocide-free antifouling in the test

Hiswa , the water industry association in the Netherlands, published a study on the effectiveness of biocide-free antifoulings in 2020. For the study, various antifouling products, such as Silic One by Hempel and simple Melkfett were tested on boats and PVC panels in various waters (salt and fresh water) in the Netherlands. The test products were applied to the surfaces for a year and taken out of the water in between for inspection. This meant that interim test results could be documented. In fresh water, all products performed more or less satisfactorily. Silic One by Hempel proved to be a really good anti-fouling product. In salt water, more extensive fouling was found on the boats and PVC panels. Up to now, biocide-free antifouling paints have been less suitable in harsh fouling conditions in salt water, and biocide-containing products have been the only alternative to protect the hull.

These test results cannot be used for other waters. Further antifouling tests would be necessary here, as different conditions (temperature, salinity, etc.) exist depending on the area. This also applies to special antifouling products. For example, an antifouling propeller test would be necessary to determine the best antifouling for propellers.

Our customers have already tested biocide-free antifoulings, as we can read in the following review by Frank S. of the biocide-free antifouling Silic One: „First of all, hats off to SVB. I called on Monday because I needed a can of Silic One. I needed it to be delivered to Enhuizen (Netherlands), as the boat was due to go in the water on Friday. The DHL delivery arrived on time on Thursday. Great stuff. We're very happy with Silic One. We first used it two years ago. After this time in the water, the hull was like new. We rebuilt some areas (the keel) and painted it with a different colour to the previous one. Red on blue, so that we would be able to see in two years exactly where reworking was needed. I have one suggestion on how to improve. Our boat is on props and before it goes into the water, these areas need painting. One whole can is too much for these areas. A quarter of a can would be more than enough."

In comparing antifouling products and carrying out tests, it is clear to see how difficult it is to determine across the board which antifouling is best. The right one for you and your boat depends on various factors that must be determined individually.

Our comparison and test also show that the best antifouling products are not necessarily the most expensive. Own label products and cheaper antifouling that we sell in our range also provide reliable fouling protection and are in no way inferior to better known brand name antifouling products.

Note: The best antifouling will only be effective if it is applied correctly.

To protect the environment and organisms in the water, it is generally recommended to use biocide-free antifouling products. Until now, these are mainly suitable for use in freshwater areas and, according to tests done by Hiswa, are a good alternative to antifouling containing biocide. You too can do your bit to protect the underwater world!

The costs of antifouling paint: How much does antifouling cost?

Depending on what you plan to do, the costs of your antifouling will be a combination of the amount it will cost to remove old antifouling and apply new paint.

How much does it cost to remove antifouling?

The costs for removing antifouling, like applying, depend on the size of the boat, and whether you intend to use a professional service provider or do the job yourself. It also depends on the method of removal.

If you decide to remove antifouling using stripper, first calculate the size of the area of the antifouling that is to be removed. The amount of stripper required can then be taken from the values given in the respective data sheet. Remember that you may sometimes have to apply stripper several times in order to remove all layers of antifouling present. In most cases, however, it is unlikely that you will be able to remove all traces of antifouling.

In addition to the cost of the stripper itself (if this method is chosen), the costs of removing antifouling will also include the tools that are needed, any equipment that can help, as well as protective equipment, such as clothing or goggles, if you do not already have these.

Note: After removing the old antifouling, new antifouling should be applied. It's a good idea to do a cost breakdown of the new antifouling. You can find plenty of helpful information and advice about choosing and applying antifouling in our guides "How to find and apply the right antifouling for your boat" and "How to properly remove antifouling from your boat" .

Protective Clothing

How much does it cost to apply antifouling?

The costs for new antifouling depend on various factors: You'll first need to decide whether to let professionals do the job or if you want to do it yourself. In most cases, money can be saved if you do it yourself, but it is not exactly a quick job, so you will also have to invest some time. The other cost influencer is the size of the boat and necessary work steps, i.e., what exactly has to be done and what is needed. Nevertheless, it is possible to roughly calculate the costs of applying new antifouling.

Total costs: Cost calculation of renewing antifouling

The total costs of renewing antifouling consist of the costs of removing the old antifouling paint and of applying the new antifouling paint. In addition to the corresponding amount of antifouling, other cost factors must be included in the calculation:

The various factors show how different an antifouling job can cost, depending on exact requirements. If you only want to treat parts of the antifouling, the costs will, of course, be much lower than if you want to remove all the old antifouling from your boat and apply new antifouling. The antifouling comparison also shows that an effective antifouling does not always have to be the most expensive.

How much antifouling paint do I need?

• Calculate the area of your underwater hull with a formula to work out the correct amount for your surface (see ."Finding & applying antifouling" guide).
• Look at the practical yield (m² per litre) specification of your antifouling product (e.g., for International Cruiser 250 it is 9 m² per/litre)
• Calculate how many litres you need for the total area of your underwater hull.
• Multiply the result by the number of coats you intend to paint (the recommended number of coats is given by the manufacturer and can be found directly on the products).
• You should now know the number of litres needed for your antifouling.
• To calculate the cost of the antifouling paint required, divide the number of litres by the yield of your antifouling paint and multiply this by the price of the antifouling chosen.
• The result is the total cost of the antifouling paint needed.

International has created an antifouling calculator that you can use to work out the number of litres required for your boat. Simply enter details about your boat, which antifouling paint you want and the application method, and it tells you immediately the quantity you need. To open the calculator, click on "How much paint do I need?" at the bottom right of the International website)

Read up on antifouling before you buy so you can find the best antifouling for your boat. Information on removing antifouling and finding & applying the right antifouling can be found in our guides remove antifouling and antifouling . More detailed information on the individual products can be found in the descriptions and data sheets. Protect your boat with antifouling and enjoy your boat trip!

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Practical Boat Owner

• Digital edition

Best antifouling paint: 8 leading options in head-to-head test

• Hugo Andreae
• April 17, 2023

Adam Fiander and Hugo Andreae test eight antifouling products on a regularly used Hardy 42 motorboat and a static panel to find out which is the best antifouling paint on the market right now…

In June 2021 we coated the hull of a Hardy Commodore 42 with eight of the best antifouling paint products. The motorboat Raymariner , which is the test boat for Raymarine, is based in the Solent and is used three or four times a week for trialling the company’s electronics.

The aim of the test was to compare traditional copper-based annual antifouling paints with a number of longer lasting and more environmentally sensitive alternatives.

We applied three non-copper antifouling paints and three traditional eroding paints plus IP Ultra 300, which is a hard coating, and Coppercoat, which is a non-eroding copper-epoxy coating.

18-month update

Raymariner was lifted in January 2022 to have a transducer replaced, so we took the opportunity to compare the results after seven months of submersion. The boat was repainted with fresh antifoul after our initial test ended, but the static panel allowed us to see how the coatings fared 18 months since the test began.

It’s important to remember that a boat would not normally sit idle and uncleaned for that length of time, making the test more challenging for all our products but especially the ‘foul-release’ coatings which rely on water movement to help shift any fouling.

Now that the boat-based test has reached its conclusion, the static panel provided a valuable cross-check for the longer term performance of the products based on a visual assessment of the stripes, a finger swipe to see how easily any fouling came away, and a sponge wipe to check if the coating itself came away too.

Like the boat, our static test panel was immersed in a Portsmouth marina location in June 2021. Apart from the effect of the tide sweeping across it, the panel has remained in situ there, fully immersed at all times for the last 18 months.

As you can see from the pictures, the coatings have, by and large, performed extremely well. Apart from silty mud covering the test stripes, there are very few signs of serious fouling having taken hold on any of the coated sections.

Even green slime – highly prevalent when Raymariner was lifted a year ago – appears to have taken a back seat in this case, perhaps because the panel has been lying in a shaded area for most of the time. Proof of how well the coatings have performed can be seen by the growth of weed and up to 10cm long sea-squirts on untreated sections.

Quick links

• Best value: Hempel Tiger Xtra 7100 – Buy it now from Amazon
• Best in test: Hempel Silic One – Buy it now from Amazon

High on slime

2021’s hot and wet weather may well have contributed to the excessive build-up of slime that greeted us when the boat was lifted in January 2022. As you can see from the pictures, slime coated all eight test stripes, some more than others. However, almost none of them showed any weed or shell growth, whereas the uncoated strips we left between some of the products were heavily encrusted.

You can see a full table of costs and specifications  below, but for the individual antifouling paint reviews we have quoted two prices. The first is our estimated price of the initial application to a typical 36ft boat (not our 42ft test boat), including the cost of any essential preparation work such as stripping and priming (but not labour or lifting costs).

The second is an estimated annualised cost calculated over a nominal six-year period to reflect the lengthier payback times of medium and long term treatments such as Silic One and Coppercoat. The table doesn’t include labour costs and some coatings may of course last longer than their specified times, including the traditional ‘annual’ antifouling paints.

8 of the best antifouling paints tested

Lasts for 10 years, but has a high initial cost

Type: Epoxy based non-eroding long-term biocide Preparation: Hull blasted back to bare GRP Initial cost: £1,948 Annualised cost: £325 (£183 without shotblast preparation)

Coppercoat uses pure copper powder set in a hard epoxy coating that should last for at least 10 years and vastly reduce the amount of copper released into the water. Coppercoat is a two-component epoxy that can only be applied to hulls that have been stripped back to bare gelcoat.

We used an antifoul removal firm to mineral-blast the test area but if you were to strip the hull yourself it would be much cheaper.

Each of Coppercoat’s five coats have to be applied wet-on-tacky. This effectively means it all has to be done during the course of a single day.

BEFORE (left): Copper colour turns a greeny blue once immersed. AFTER (right): Some slime evident but no weed or barnacles

Once dry, the coating needs to be burnished with 400-grit paper to expose the copper and activate the coating. The only ongoing/annual maintenance required is to clean (typically pressure-wash) the boat from time to time.

The results show a similar level of protection to the other copper-biocide alternatives. There may be a little more slime than some but in fairness to Coppercoat, theirs is a slow-release long-term solution and seven months is barely one season’s worth of use.

The initial cost is higher than most, partly due to having to blast off old antifoul (brand new boats just need sanding), but its annualised cost after six years is much the same as traditional antifouling paint and it would carry on getting cheaper after that. Nor does this take into account the substantial saving on labour time.

Before a thorough wipe-down (left) and after (right)

Even though Coppercoat recommends an annual scrub or pressure wash to remove any surface growth, it still seems to be performing well after 18 months untouched. There was no significant fouling on the exposed copper surface, which has now adopted its characteristic blue/green colour, and minimal resistance from the swipe tests, suggesting any surface growth would fall away on a regularly used hull.

As expected of a tough epoxy based product there was no sign of the coating coming away on the sponge. Coppercoat’s claims of it being more environmentally friendly than erodible coatings.

Buy it now from coppercoat.com

Note: We may earn a commission when you buy through links on our site, at no extra cost to you. This doesn’t affect our editorial independence.

Silic One was the best performer, but it is fiddly to apply

Hempel Silic One

Editor’s choice – best in test

Type: Non-biocide, silicone based foul-release coating Preparation: Hempel Light Primer (4 coats), Silic One Tie-Coat (1 coat) Initial cost: £1,045 Annualised cost: £233

Silic One had the most stringent set of application instructions of our group. It’s strongly advised to apply it on to a stripped hull but, if the existing coating is in good order, a barrier coat of Hempel’s Silic Seal will enable the switch.

Commencing with Hempel’s two-component Light Primer, the bare surface must be built up with a minimum of four thin layers. Next, a tie-coat must be applied while the last coat of primer is still tacky.

After two hours the first of two coats of Silic One can be applied, the second a minimum of eight hours hours later, then a 16-hour minimum drying time before immersion.

BEFORE (left): Smooth rubbery surface makes it hard for fouling to grip. AFTER (right): Impressive result – no weed, barnacles or even slime

If it sounds like an involved process that’s because it is, taking nearly three days from start to finish once drying intervals have been factored in. However, the results speak for themselves.

After seven months, Silic One has performed the best of all our group, with no signs of weed or shell growth and the least amount of surface slime. It also wiped off exceptionally easily. An impressive result for a biocide-free antifouling paint.

Because it has a recommended lifespan of two years before topping up with one fresh coat of Silic One, the high initial application cost is offset over time.

Its six-year annualised cost comes in lower than all other products on test except Hempel Tiger Xtra 7100 and Coppercoat if you exclude the cost of shotblasting.

We had expected foul-release coatings to struggle on a static panel without any movement through the water to shift surface fouling. However, the majority of the stripe stayed remarkably clean and any slime was easily swept aside with the swipe test.

Some isolated growth can be seen at the top of the strip but this could have been caused by migration of fouling from the untreated section in-between this and the Seajet Bioclean Eco (the other products were separated by a strip of white Trilux antifouling). So far there are no signs of any surface deterioration.

Buy it now from Amazon

Impressive value, but needs applying every year

Hempel Tiger Xtra 7100

Editor’s choice – best value

Type: Soft eroding biocide antifouling Preparation: Hempel Underwater Primer (2 coats) Initial cost: £298 Annualised cost: £167

While it might not be the most technically sophisticated formulation out there, for many boat owners Tiger Xtra has become a go-to product – a reliable staple and a firm favourite on the winter maintenance list for the past 20 or 30 years.

With one of the highest m2/ litre coverage rates of anything tested here, applying Tiger Xtra will soon have you making decent progress across the hull in a relatively short space of time. The prospect of coating even larger than average-size hulls needn’t be as daunting, or as expensive, as you might have first imagined.

The question is, does it work? And the answer to that question is yes, in a similar way the other fast-eroding formulations have benefited from the vigorous, weekly use that Raymariner has been subject to these past seven months.

BEFORE (left): Easy to apply and leaves a smooth finish. AFTER (right): A similar amount of slime, but easier to wipe off than others

Self-polishing mechanisms need movement of water across the hull and Tiger Xtra has proved its formulation is still a worthy contender even after all this time. Slime was also a little easier to release from this coating, compared to some of the others.

The only unknown quantity is whether this more thinly spread coating would continue to deliver over a longer length of time, especially in warmer waters with higher fouling.

Hopefully, we’ll get a chance to monitor this on our test panel but on this showing it represents good value for money compared to its similar performing annual rivals.

We were pleased to see how well the cheapest of our traditional antifouling coatings coped on the boat and the results from the panel did nothing to change this view. Our initial inspection showed no more fouling growth on this than any of the more expensive products and the finger swipe test easily shifted anything that was there.

Some of the coating surface colour did transfer onto the sponge, which is normal for a soft eroding coating, but over time it might start to wear through on a fast, regularly used boat.

Easy to apply, average performance

International Ultra 300

Type: Hard eroding biocide antifouling Preparation: Primacon (1 coat) Initial cost: £446 Annualised cost: £326

Prior to this test Raymariner had been coated with International’s Micron 350. When it was lifted in June 2021 in preparation for our test patches, the hull had appeared in remarkably clean order.

This time around we opted for Ultra 300 Hard, as the hard and slow-eroding formulation lends itself well to fast or regularly used motorboats. It would also be suitable for yachts on drying moorings that need a harder antifouling paint.

After applying just one recommended coat of primer, we applied two, good coats of Ultra 300 in a straightforward and fuss-free way, making life so much easier for the DIY applicator. Job done.

BEFORE (left): Another easy to apply coating that leaves a smooth finish. AFTER (right): The usual layer of slime but a bit harder to shift than some

The results have been good, but marginally less impressive than Micron 350 looked back in June, although that could be down to seasonal differences in water temperatures and fouling growth.

The Ultra was sheathed in a film of slime, thicker near the waterline, as expected. And when we tried to wipe the slime away with a damp microfibre towel, it showed quite a lot of resistance, suggesting it had taken hold quite firmly – though nothing that a jet-wash wouldn’t shift, and with no long beards of weed, or signs of shell growth.

At an annual cost of around £326 for a typical 36ft boat (£446 if you include the cost of a primer coat), it’s a solid, easy to apply performer.

Although this is a traditional copper-based antifouling, it is a slow eroding hard coating designed for faster planing craft with increased water friction that might wear through softer products.

This didn’t affect its performance on our static test panel with little fouling growth over the 18 months and no sign of it starting to lose its antifouling properties. The swipe test suggests any fouling would fall away on a moving hull used regularly, while the sponge test showed only slight signs of the coating releasing itself.

Slime is easy to shift, but this antifoul is pricier than most

Jotun NonStop II

Type: Soft eroding biocide antifouling Preparation: Jotun Megacote Epoxy (4 coats), Megasealer Epoxy Tie-Coat (1 coat) Initial cost: £463 Annualised cost: £355

As we’d stripped Raymariner ’s hull back to the bare gelcoat Jotun decided to send us their epoxy primer, tie-coat and combined anti-osmosis system, prior to applying the two final coats of Jotun NonStop II.

While this belt and braces approach makes sense on a brand new hull, we felt for the purpose of our price comparison table it would be fairer to use the costs of Jotun Vinyl Sealer – a straightforward one-component product that we have been assured can also be applied to bare gelcoat.

Jotun Vinyl Sealer is ideal for those looking to antifoul an already treated hull in good condition and is a readily available product the DIY user would be more inclined to buy.

BEFORE (left): Blue is one of several colours available in this range. AFTER (right): A decent result comparable with other more traditional antifoulings

If the existing coating is a known Jotun product and in good order, with no damage or signs of flaking, Jotun NonStop II can be applied without even needing a primer.

The results in January showed good overall performance, broadly similar to the other copper-biocide products, with no significant weed or shell growth to talk about but a thickish layer of slime that shifted quite easily when given a wipe with the towel.

Even using the basic vinyl primer for the initial application, the annualised cost still makes this one of the pricier options so it will be interesting to see if it lasts longer than the cheaper options over time.

This premium priced self-polishing coating uses ion exchange technology to ensure a steady release of biocides throughout the year, even when the boat is not being regularly used. While it performed well it wasn’t noticeably better than some of its cheaper competitors.

However, it did have the highest degree of coating surface being released onto the sponge suggesting it was eroding consistently even without regular boat movement – a good thing as long as it has been applied in sufficient quantity.

Buy it now on Amazon

Solid performer, but needs regular stirring

Seajet 033 Shogun

Type: Soft eroding biocide antifouling Preparation: Seajet 015 Primer (2 coats) Initial cost: £486 Annualised cost: £289

When we heard about a new non-biocide alternative from Seajet, it made sense to compare it alongside Seajet Shogun, its best-selling, copper-based formulation.

Backed by the commercial resource of Chugoku Marine Paint, Seajet first appeared in the UK about 20 years ago and carved a niche for technical-quality antifouling paints.

Despite the fact Seajet products are often found on the lower reaches of chandlery store shelves, Shogun is a reliable performer and a product that many boat owners have become fiercely loyal to.

BEFORE (left): Needs a good stir but paint goes on evenly. AFTER (right): Another solid performer with no shell or weed growth

One thing we found when applying Shogun is the copper and zinc volume solids sink to the bottom and to achieve a homogeneous consistency, it’s important to ensure a good 5-10 minutes of continuous stirring with a wide blade stirring stick, not just the screwdriver you used to prise the lid off.

The vapour given off made us glad we were outside in the fresh air but the coating itself goes on in a thick and consistent way.

Largely in-keeping with the other self-polishing brands on test, close inspection returned a good, solid performance, with no signs of shell growth, or significant plant or weed growth to talk about. The extra coat of primer added a bit to the initial cost of application but in subsequent years the cost comes down considerably.

Sold as a premium self-polishing annual treatment for boats capable of up to 40 knots in areas of high fouling growth, this antifouling treatment still seemed to be performing well after 18 months on our static panel.

There was minimal surface growth and only a light smattering of slime. As expected, a certain amount of blue coating did release onto the sponge when the panel was wiped, suggesting it will eventually wear through and reminding us not to skimp when applying this type of erodible coating.

Boasts a 3-year lifespan, but we did see some fouling migration

Seajet Bioclean Eco

Type: Non-biocide, silicone based foul-release coating Preparation: Seajet 117 Multipurpose Epoxy Primer (3 coats), Seajet Bioclean Tie-Coat (2 coats) Initial cost: £1,011 Annualised cost: £268

Seajet Bioclean Eco has a rubbery-like finish that fouling finds difficult to adhere to. It is a seven-coat full system on bare gelcoat but can be applied on top of existing antifouling in good condition, with two coats of tie-coat, followed by two coats of Bioclean Eco.

Dry weather meant we made steady progress, first with three coats of epoxy primer, then the coloured tie-coat stage before two good coats of Bioclean Eco, a thick and transparent, paste-like substance. On Seajet’s advice we used a clean mohair roller head to achieve the required film thicknesses.

BEFORE (left): Shiny silicone- based foul-release system is available in several colours. AFTER (right): Almost no fouling bar some migration of growth from the untreated dividing strip

When lifted, the test strip was admirably clean and foul-free but there were some patches of fouling that appeared to have migrated across from the untreated dividing line separating this test patch from the neighbouring one rather than starting life on the surface of Bioclean Eco itself.

The amount of slime was less than on the biocide products and the wet microfibre towel test showed that resistance to removal was also less.

Seajet expects it to last for at least three years after which another tie coat and top coats are likely to be needed, although as this a new product the recommended routine isn’t yet fully established. The PBO Project Boat, a Maxi 84 , has been coated with Seajet Bioclean Eco so we’ll be able to update you in due course.

As with our other foul-release coating, this performed far better than expected on our static panel, suggesting it would still provide good protection on a less frequently used boat.

Fouling clearly finds it hard to adhere to its slippery, rubber-like coating even in a static situation like this and the swipe test suggests it would perform even better on a regularly used boat.

There were signs of isolated growth at the top and bottom but this could have been caused by migration of fouling from the untreated section between the two silicone-based coatings.

Buy it now on seajetpaint.com

Great for topsides, not so good underwater

Ceramic Pro

Type: Biocide-free ceramic based nano-coating Preparation: Smooth bare gelcoat Initial cost: POA, for above-water use only

In fairness to Ceramic Pro, they were keen to be involved in this test as much for their own ongoing research as for ours, to see if their protective ceramic coating designed primarily for use above the waterline, would also prevent fouling below it.

Hugo Andreae, editor of our sister title Motorboat and Yachting (who we jointly ran the test with), has used Ceramic Pro to good effect on his own boat .

The hydrophobic surface makes it easier to clean and it has become a popular treatment among professional boat valet and ‘detailing’ companies, who find it provides a tough and permanent barrier against salt-deposits, exhaust fumes, surface oxidation, staining, bird-droppings, and that ugly line of filth commonly seen around the boot-top, just above the waterline.

BEFORE (left): Ceramic Pro looks great above the waterline. AFTER (right): But it didn’t seem to deter fouling below the waterline

It was hoped that this would also prevent fouling from attaching below the waterline, however the micro-organisms that lurk in the Solent’s tidal waters proved too persistent.

Even though the fouling was not too difficult to remove, shell growth and plant life had clearly taken hold and probably would have become worse over an even longer period of time.

Ceramic Pro told us pricing for boats is on a case-by-case basis and as the product was not successful as an antifouling it was not included in the results table below.

18-month update: N/A

Buy it now from ceramicpro.co.uk

Full price comparison – click to enlarge

Verdict: Which is the best antifouling paint?

Almost all of the coatings did an effective job of keeping fouling at bay but there were some notable differences between them, not just in terms of performance but also cost, application time and environmental credentials.

Coverage rate per litre was different according to the product. Coppercoat do not state a coverage rate but prefer to calculate the amount you need based on your boat type and length. All the figures on the table were based on a 36ft motorboat hull, of 34m2 surface area.

The silicone based biocide-free alternatives performed very well, especially Hempel’s Silic One . If you’re prepared to put up with the higher initial cost and time taken to apply these products for the first time, they really do deliver on their promise and the price differential reduces over time.

Antifouling stripes were applied to the hull of Raymarine’s electronics test bed vessel Raymariner , a Hardy Commodore 42, in June 2021

They won’t suit every boat, however, as silicone can dry out if left unsubmerged for long periods and may start to wear through if kept on a dry-stack or drying-mooring, but for the majority of boats they look like an effective alternative to copper-based antifouling paints.

Coppercoat’s tough finish is fine to use on a drying mooring or dry stack and has the next best eco-credentials of our group. It performed almost as well as the traditional annual antifouling paints but should last for 10 years or more with minimal annual upkeep.

It does have to be applied to bare gelcoat, though, which ramps up the initial cost. On our fictional 36ft boat we calculated the break even point at about six years but this would come down substantially if you included the annual labour costs or were applying it to a brand new boat that didn’t need stripping.

Adam Fiander coated the hull of Raymariner and a test board for immersion in a marina

There was little to choose between the traditional biocide antifouls, which supports the view that if you prepare the surface and apply it properly most antifouling paints will do a decent job of protecting your boat, at least over the course of a single season in UK waters.

Hempel’s budget offering, Tiger Xtra , is still providing incredibly good value protection after all these years, and Seajet Shogun , International Ultra 300 and Jotun NonStop II have proved their worth with solid, reliable protection that was impossible to split during the course of our initial test period.

The panel-back after 18 months without antifoul

18-month update conclusions

While the results of the long-term panel test have helped to back up the findings from our original boat-based test, there was not a big enough difference between the performance of the various different coatings to justify changing any of our original boat-based star ratings.

All seven products provided a good degree of antifoul protection when compared with the growth on even the smallest untreated sections of the panel. The extra fuel cost in dragging a carpet of unsightly fouling like this on the underside of your hull does not bear thinking about.

Our tests prove that even a moderately priced traditional copper biocide can provide all the short-term protection you need. But be prepared to keep an eye on soft, self-polishing and erodible coatings such as Seajet Shogun , Hempel Tiger Xtra or Jotun NonStop 2 , because they will need topping up each year or re-applying in full every two seasons.

The fact that our test panel wasn’t moving may have helped extend the life of these products. Hard coatings such as Coppercoat or International Ultra 300 lend themselves to the extra friction from faster hulls but may need occasional scrubbing to maintain their performance when the surface layer starts to lose its potency.

The sponges used for the wipe test

They are designed to withstand being scrubbed and should not get damaged if you keep your boat on a trailer or in a dry-stack. However, on the basis of this long-term panel test, they seemed to maintain their performance for the full 18 months without any intervention and in the case of Coppercoat should carry on doing so for years to come.

If you’re willing to invest the extra time and cost of applying a silicone-based foul release coating, either of the two that we tested will, on the evidence of this test, do a very good job for you, even if your boat isn’t used that regularly.

The fact that they do this without the use of biocides can only be a good thing for the long-term health of our rivers and seas. You do need to follow the instructions carefully, because each of the three stages of primer, tie-coat and top-coat need correct application for the coating to perform well as a whole.

However, once applied, they should last for several years but tread cautiously with your annual maintenance routines, because a powerful pressure-washer can dislodge the layers if held too close.

Tightening antifouling paint regulations

These days, many of our buying decisions are influenced by our desire to be mindful of the environment. Antifouling paint is no different, and the Biocidal Products Regulation means manufacturers are subject to ever tightening regulations controlling the substances they are allowed to use.

Copper is still the most widely used biocide in antifouling paints. Described, variously as copper powder, dicopper oxide or cuprous oxide, copper represents anywhere from 25% to 55% of the volume solids of many formulations.

BEFORE: As Raymariner looked when she was launched in June 2021

This is suspended in a paint matrix that gradually erodes as water passes the hull, releasing biocide at controlled rates, depending upon whether it’s a hard or soft-eroding type. It is the build-up of these biocides in marinas, harbours and waterways that poses a risk to larger marine wildlife.

Coppercoat is the exception to the rule, because although it counts as a biocide, it uses copper granules set in hard epoxy resin that not only gives it a lifespan of 10 years or more but ensures that only minute quantities of copper are actually released into the water.

Alternative antifouling paints

As the net tightens some countries now ban the use of copper antifouling paints, so manufacturers are coming up with a number of biocide-free alternatives. Silicone based formulations – such as Seajet Bioclean, which we used when applying antifoul to the PBO Project Boat – are among the most promising alternatives.

These prevent fouling through the physical properties of their super smooth hydrophilic surface rather than biocidal action. In other words, the coating is simply too slippery for marine fouling to attach itself.

AFTER: As she looked when she was lifted towards the end of January 2022

It’s all very well having strong eco-credentials but we wanted to find out if these silicone-based alternatives work in a range of different biofouling conditions. Do they, for example, stand up to the rough and tumble of the dry-stack, and will their multi-coat regimes and strict instructions for pot lifetimes and overcoating intervals appeal to the pressed-for-time DIY and professional user?

Didn’t find what you’re looking for? Head to Amazon’s dedicated boating page for more marine products.

The Fastest Boat Bottom Paints: Antifouling for Speed

Whether you're racing your boat or cruising casually, everyone wants to sail faster. Is there a bottom paint that will make your boat sail faster? And is it right for you?

What are The Fastest Boat Bottom Paints? The fastest bottom paints are vinyl or Teflon based hard paints, which can be wet sanded and burnished to a smooth finish .

Maintaining a fast, racing finish with these paints requires more maintenance than a hard copolymer or a softer ablative paint. It is more maintenance, but it can make a big difference in boat speed.

On this page:

What slows you down, bottom preparation is everything, maintaining the finish, alternatives to hard and burnished, how much faster is it, what are your goals, racing vs. cruising.

In a word: friction. Friction causes turbulence and drag

Without requiring a degree in Computational Fluid Dynamics to explain it, a rough bottom is slower. More friction is slower - think about rubbing your hand across a carpeted floor versus a glass table top with a little oil spilled on it. Which is easier? Now imagine you're playing with a toy boat on either surface. If you push the boat, which one will be easier to push? Which might even keep sliding a little if you let it go?

Getting more into the science (still without the degree!), when fluids move over a surface there is a "boundary layer," the layer of fluid closest to the surface skin. When a hard surface moves through a liquid, molecules of the liquid get dragged along with it. This increases "skin friction" and causes drag. The faster something moves, the more drag.

If the flow of molecules in the boundary layer is "laminar", it is evenly spread and more calm. A "turbulent" boundary layer pulls more water with it and causes more friction and drag. A smooth bottom helps maintain laminar flow and reduce turbulence and drag as the boat speeds up.

These forces can be considerable if a boat bottom is not a fair surface, and the effect is more pronounced at higher boat speeds.

Given the power provided from your sails is constant, a boat with less drag will move through the water faster.

Spraying a layer of VC Offshore or Baltoplate on your boat will not make it instantly faster. To get the full benefit of a hard, fast bottom paint job the surface bottom must be prepared with care.

• Old incompatible bottom paint must be stripped. You can't put a Teflon based paint over an ablative or copolymer paint. It won't stay on.
• The bottom should be "faired." The aim is to create a smooth, curved surface with no bumps, dips or ripples. This is labor intensive and requires expertise and a keen eye to fair a hull.
• The bottom should be sanded smooth after fairing and before painting. Even if an orange is round and fair, if you spray paint it you will not end up with a smooth surface. You must start with a smooth surface.
• For a fast finish, spraying gives an even, smoother coating and reduces the amount of sanding time. Rolling hard bottom paint makes little sense because of the increased work from the rough paint application.
• Sanding and wet sanding is a must. Sprayed paint will still feel rough to the touch. For a fast finish sanding and wet sanding with up to 400 grit sandpaper will get results.
• Burnishing is a step even farther than wet sanding, and can give a mirror finish to a well prepared bottom.

Hard bottom paints designed for racing are not as effective at preventing grown as softer ablative paints or copolymers. They don't hold as much active antifouling, and it doesn't leach out of the paint or get refreshed since the paint doesn't slough off. And wet sanding and burnishing both remove some surface active ingredients.

In high growth areas, a racing finish with require constant maintenance and cleaning. When I raced my last boat, I had a diver come every week to clean the bottom and we dove on the boat ourselves at major regattas. You won't get hard growth quickly, but you will get slime buildup in very little time which can slow you.

You may not get two seasons from a coat of racing paint. If you don't, you'll want to wet sand it before the start of the season to ensure everything is smooth and ready again. The good news is that a properly prepared bottom is easy to re-spray and sand back to a good finish compared to the first time you do it.

What if you don't dive, can't clean your boat regularly, or don't want to pay a diver? Maybe you just want to go faster but aren't a speed-mad racer looking for every 1/10th of a knot speed extra?

Dry sailing for smaller boats is very popular. Fair the bottom and leave it unpainted or put on an underwater epoxy paint. As long as you don't store the boat in the water for more than a couple of days during a regatta there shouldn't be any growth. Most dinghies are dry sailed. Many smaller boats kept at clubs or marinas with a crane have this option, though there may be a cost to haul and launch.

If you stay in the water, a good choice is a hard copolymer paint. These are often referred to as "self polishing," as they smooth themselves with use as the paint sloughs off. Many of these are quite hard and can be carefully sanded to a smooth finish. Since they’re softer, you don’t want to sand through the paint. With proper preparation before painting, a sprayed paint job, and a little sanding, your bottom can be almost as fast as the high maintenance race boats.

Even without the sanding, a good bottom preparation before painting can give you more speed on passages. These paints are popular with long distance cruisers and people who use their boats frequently. You'll lose a little edge if you're racing, but you won't put yourself at the back of the fleet with it.

"What are you getting for your money" is a common question when preparing a boat for racing. The faster bottom and the newest sails won't win races for you if your crew can't tack or gybe and you can't spot wind shifts. You can lose the entire advantage of that quarter knot speed increase with a blown tack or a missed shift.

From personal experience, replacing a rough, coarse, orange-peel looking bottom with a polished and burnished bottom made a big difference. Both in my boat speed, and my wallet. It was expensive to do and expensive to maintain. But the boat was faster, and we were racing competitive regional events. The difference was most noticeable at low speeds and in light air.

There is not a lot of empirical data about how much faster a burnished Teflon bottom is over a well prepared copolymer paint. So the answer is "yes, it's faster," but with your boat, your budget, and your application there’s no way to predict that you may be 5% or 10% or half a knot faster.

To the casual club racer or cruiser, is it worth the time and money to prepare and maintain the fastest of possible finishes? It may not be; that's a question that only you can answer.

The best choice for a fast bottom comes down to you, your boat, and how you will use it.

• Are you a racer? If yes, is it weeknight club racing, or are you racing at higher level regional events against serious racers?
• If you cruise, how much maintenance are you willing to do to keep every extra fraction of a knot of speed?
• Where do you sail? Some areas have more aggressive growth than others. A sailor in the Great Lakes may get away with a hard bottom paint with less work than a New England coastal racer or a cruiser in the Caribbean.
• What is your budget for bottom preparation and maintenance? Are you willing and able to do some yourself?
• What us the current condition of your bottom? How ready is it for a top quality refinishing?

You will find very few non-racers who take the time and effort to apply the fastest bottom paints. The cost/benefit/effort analysis doesn't show a reasonable payback for what you get.

Most sailors aren't taking their boats to world-class regatta venues, they're taking off for weekends and vacations and maybe doing the club series on Wednesday nights or the annual regatta. Most of those boats are not going through the expense and effort for a competitive racing finish.

On the other hand, if you're racing in a competitive one-design fleet at New York Yacht Club Race Week or the San Diego NOOD Regatta, you can bet almost every boat in your fleet will have a smooth, wet sanded finish.

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You may also like, do i need to antifoul (bottom paint) my boat - sometimes.

Any time you buy a new boat, you get a work list as long as your arm. Bottom paint is expensive, toxic, and can be difficult to apply. It's an easy task to want to …

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Better Sailing

Best Antifouling Bottom Paint for Boats

Applying antifouling paints on your boat will eliminate marine growth and maximize your boat’s efficiency. Bottom paints contain chemicals that prevent underwater growth in order to protect your hull. Most paints contain copper compounds while others are water-based or copper-free. Basic types of antifouling paints include ablative bottom paints and hard bottom paints. As we’ve previously seen in another article, there are different groups and types of bottom paints. In general, before painting the hull, you should first consider how often you use your boat and what type of paint you applied in the past. This is because not all paints are compatible with others. For instance, vinyl paints should only be applied on previously vinyl-painted surfaces. But let’s now see which are the best bottom paints for boats as well as which one suits your boat! Follow me!

How to Choose the Best Bottom Paint for your Boat

Choosing the best bottom paint for your boat is not a simple decision to make. And, how will you choose from all these available options in today’s market? Keep reading so as to put things in order and give an answer to your concerns. Here are the most important factors to keep in mind before selecting the right antifouling paint for your boat.

• The type of your boat, the average speed, and boat usage : The frequency in which you use your boat, and what type of boating you do are also important factors before choosing a bottom paint. For example, if you’re an occasional sailor then a single-season antifouling paint will work just fine. But, if you’re regularly sailing overseas then it’s recommended to use a multi-season and effective bottom paint. Also, in case you trailer your sailboat then consider an ablative antifouling paint.
• Your budget and desired durability of the paint : Bottom paints tend to be expensive. But, as aforementioned, if sailing frequently then it’s advisable to use a highly-durable, effective, and environmentally-friendly bottom paint. Some properties that increase the cost of an antifouling paint are the amount of biocide, multi-season effectiveness, self-polishing ability as well as the level of preventing marine growth.
• Previous and existing hull coatings: If you have already painted the hull then you need to know whether the new bottom paint is compatible or not with the previous one. However, in case you don’t know the type of the previous paint or if you think that it’s incompatible with the new paint, it’s better to remove it completely before applying the new bottom paint.

Environmental Factors

Other important factors to consider are related to the environment. On the one hand, the environment in which you’re sailing will determine what kind of bottom paint you’re going to use. On the other, environmental restrictions and regulations play a huge role in the matter of antifouling paints. This is because the use of biocides in the marine environment has proved to be really harmful as it has considerable toxic effects.

• Water environments to which you’re sailing to. Are you sailing in freshwater or saltwater environments? The answer will determine the type of fouling, i.e. light, moderate, or heavy, and how you can deal with it. Copper-based paints are considered the most effective ones but also the most toxic for the marine environment. Copper-free paints, such as ECONEA, are also effective on hard fouling organisms, like acorn barnacles. But, in case algae and slime cause a problem in the sailing area you’re going to, you might want to use a paint containing an algaecide such as zinc pyrithione. Keep in mind that more biofouling occurs in warm waters rather than colder ones.
• Environmental restrictions:  As sailors, we have to be responsible and protect the marine environment. There are specific restrictions that regulate VOC (volatile organic compound) and copper content in certain areas. Also, many places require the use of ablative antifouling paints that are water-based, and that’s a huge plus!

How to Apply and Remove the Antifouling Paint

Tips for applying new bottom paint:.

• Firstly, give a high-pressure freshwater wash and rinse the hull thoroughly.
• Select the right paint accessories and safety equipment for the paint you are applying. Always wear a respirator, gloves, protective eyewear, and special clothing.
• Check for damages with suitable epoxy filler and inspect the hull for Gelcoat damage or osmosis.
• Place a tarp or filter cloth under the hull to catch the spills.
• Follow the manufacturers’ instructions that recommend the number of coats needed. 
• Apply the antifouling at the correct thickness. This depends on application methods and conditions.

Tips for Removing Bottom Paint:

There are three ways for removing antifouling paint and they include sanding, chemical paint strippers, or soda blasting by professionals. The tips below are referred to the paint stripping option.

• Scrub the hull and use a stripper for changing the bottom paint. The  Back to Nature strippers  are environmentally safe and easy to use.
• If you decide to sand in order to remove layers of paint then make sure to solvent-wipe the surface prior to sanding so as to remove any grease, dirt, and wax.
• Place a tarp under the sailboat to catch scraping chips.
• Avoid removing large areas of antifouling by dry sanding. This is risky for yourself and for the environment. It’s advisable to place a tent over the boat in order to restrict airborne particles. Also, try to wet sand and consider using a vacuum sander to remove old paint.
• Collect any waste and safely dispose of them in a hazardous waste receptacle.

Best Bottom Paints

Cfa eco — copper free ablative.

A copper-free paint with a formula of ECONEA and Zinc biocide that ensures multi-season protection. This dual biocide is quite environmentally safe, works great against slime, has low VOCs, and has no intense smell. You can safely use it on all substrates including aluminum .

Sea Hawk Tropikote

This hard epoxy antifouling paint uses high-quality cuprous oxide and fights effectively all kinds of marine growth and slime. Moreover, with this paint, you’ll avoid regular maintenance. It’s a great coating for year-round boaters. Check it out on Amazon .

Pettit Ultima Eco Bottom Paint

This metal-free paint contains a dual biocide that efficiently controls both hard and soft fouling on different substrates. The paint contains organic ECONEA biocide and a powerful slime fighting agent. Lastly, the self-polishing ablative technology eliminates the need for sanding and paint build-up. Check the product right here .

TotalBoat Underdog Boat Bottom Paint

This high-quality solvent-based antifouling paint offers excellent protection qualities. It has a powerful paint formula and effective ablative action that protects the boat from all kinds of marine growth. The formula releases approximately 25% of copper at a controlled rate that keeps away the light or hard growth of grasses, algae, and slime. See more details about the TotalBoat Underdog Boat Bottom Antifouling Paint on Amazon .

Rust-Oleum Marine Flat Boat Antifouling Paint

This paint is ideal if you’re launching your boat after a long time. According to reviews, its excellent performance prevents barnacles, algae, and other marine organisms from growing on the hull. It has a durable protective coating which works great on steel surfaces but not on aluminum ones. Moreover, it contains around 45% of cuprous oxide that makes it one of the hardest bottom paints. Check it out on Amazon .

Interlux Ultra with Biolux Antifouling Paint

This paint’s formula is excellent for high fouling areas and ensures long-term antifouling protection. It benefits from the fast dry and low VOC formula that allows painting and launching your boat on the same day! Check it out right here .

Flexdel Aquagard Antifoulant Bottom Paint

This eco-friendly water-based paint is highly-efficient for application on different surfaces and ensures a quick dry. By applying several coatings you ensure longevity and prevention of marine growth. Even though it’s expensive it really worths the investment, so, check it out right here .

Aluma Hawk Aluminum Boat Paint

This paint is ideal for application on fiberglass and aluminum boats. Highly preferred by many sailors due to its effectiveness and ease of use. By applying just one to two coatings you can save some time and effort. Moreover, it dries quickly and prevents corrosion but it’s quite thick, so make sure to use a thinner before applying. Check out more details on Amazon .

Pettit Paint Hydrocoat ECO

This water-based and copolymer ablative bottom paint wears away with use, reveals a new surface, and then eliminates paint buildup. It contains the highest level of ECONEA which protects both the hull and the marine environment. Along with the slime-fighting inhibitor, the formula offers multiple seasons of protection. In addition, there’s no need to sand between coats, and depending on the environment, it will likely last for multiple seasons. Lastly, the copper-free formula is great for different substrates like steel, GRP, or aluminum. Check it out on Amazon .

TotalBoat Krypton Boat Paint

Another environmentally friendly ablative paint from TotalBoat that ensures effectiveness and ease of use. This is because its great formula contains a sufficient concentration of ECONEA combined with slime-fighting zinc. You can apply it on aluminum, fiberglass, steel , or even wood sailboats in both fresh and saltwater. Furthermore, you can use it on different underwater metals such as outdrives and trim tabs. It comes out in five colors and is available in gallons or quarts. Check the TotalBoat Krypton Copper Free Antifouling on Amazon .

Best Boat Bottom Paint – Summary

In order to find out which paint is the best for your boat keep in mind some important factors. Firstly, if you’re sailing in a freshwater or saltwater environment. Secondly, the environmental restrictions and negative impact that the paint will cause on marine life. Thirdly, if your boat will be trailered or stay in the water year-round. Also, the material of your hull and, of course, how often you use your boat. If you know these key factors then you’ll be ready to choose between the above-mentioned antifouling paints. These paints are considered the best in today’s market. Lastly, I highly encourage you to purchase eco-friendly and water-based paint because nowadays, they’re as effective as copper-based or hard epoxy paints are. I hope that this article was helpful and that you’ll be able to easily choose the best paint for your sailboat!

Peter is the editor of Better Sailing. He has sailed for countless hours and has maintained his own boats and sailboats for years. After years of trial and error, he decided to start this website to share the knowledge.

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Propeller Paints that Last

Prop antifouling research spins into new territory..

A cheap, effective antifouling paint for a propeller is as rare as a good pun. The coating must not only ward off all marine growth, it must present a smooth slick surface that can stand up to the constant water friction when the boat is under power. And in the case of a folding prop, the coating must also adhere in nooks and crannies and, in some cases, even withstand metal-to-metal contact. These demands are well beyond the reach of any run-of-the-mill marine coating. Thus, our search for-wait for it-a prop(er) paint.

Yes, you can paint a bronze propeller with conventional, copper-based hull paint, but it wont do much good, since the more noble metals in the bronze prop will eventually waste away the copper biocide. Dont even think about painting an aluminum outdrives or prop with a copper paint, or the reverse will occur-the more noble copper will attack the outdrive alloys. Even with the right preparation, regular bottom paint tends to wear quickly on a prop due to increased water friction.

Practical Sailors search for longer lasting prop paints has led us down many rabbit holes, and eventually to the Land Down Under. For the past several years, Practical Sailor tester Jonathan Neeves has been conducting a series of antifouling paint field trials on his 38-foot catamaran based in Sydney, Australia. Some of the work is aimed at supplementing our paint panel tests of hull paints, (see Bottom Paint Checkup , PS March 2016), but the main purpose of the most recent trials has been to evaluate the real-life performance of propeller paints.

Paints for Props and Running Gear

For the past few years, Neeves has been trying to find a paint for props, saildrives, and running gear that matches the life of the antifouling on his hull. The seasonal sailor who hauls and paints every year doesn’t need this level of performance, but for a year-round sailor, a good multi-season prop paint can yield big savings.

The selection of paints specifically for propellers is limited. Neeves has tested four different products on his boat: Velox, Prop Speed, PropOne (formerly known as Prop Gold), and Interlux Trilux. In separate trials aboard a monohull based on the Chesapeake, weve tested Prop Speed and Mussel Buster, a professionally applied bake-on coating. The results from these propeller paint tests are averaged in the adjacent table. (Another product, Prop Purr, has since entered the market that we will be testing for the first time this spring.)

In this report, we detail the results of Neeves most recent test-a comparison of Velox and Prop One. Like conventional bottom paint, Velox relies on biocides to fight marine growth. Prop One, like Prop Speed, is characterized as a foul-release coating-sometimes called a fluoropolymeric or silicone paint. It contains polytetrafluoroethylene (Dupont brand Teflon). Prop One depends on its rubbery, slick surface coating surface to prevent barnacles from latching on.

Application

The makers of Prop Speed and Prop One discourage amateur application. They prefer their products by applied by professional applicators. One reason for this is that the coating process requires special care. (Neeves went through a training course in order to become a qualified applicator for Prop One.) If you intend to apply either product yourself, we suggest you work very closely with the manufacturer, and ask specifically about any safety precautions to take when applying and removing the paint.

Applying Velox is more straightforward-prep, prime, and paint. An amateur can handle the job himself, although we recommend calling the maker (or qualified distributor) before painting. The instructions in the U.S., Australia, and Europe vary (and even can be contradictory).

Most props require very little paint. Even if you buy the smallest size kit available, youll have some left over, and you might not be able to re-use it. Weve reused Velox after more than a year, and Prop Speed and Prop Gold have an 18-month shelf life. Again, check with the manufacturer regarding shelf life before you plunk down $200 for more paint than you can ever use.

If you are re-applying Prop Speed or Prop Gold you need to strip off the old coating and get down to bare abraded metal every time you apply a new coating. If you are re-applying Velox, you can lightly sand the old paint using 120- grit sandpaper, re-apply primer where necessary and re-coat with the topcoats.

You can use a stainless steel wire brush on an angle grinder to remove old coating. Other PS testers recommend an 80-grit lap wheel. In either case, be sure to wear eye protection. After grinding, wash well with water and apply the primer coat. Do not touch the bare metal with your fingers, it will leave grease and the primer will lack adhesion. Neeves used latex gloves while cleaning and abrading. Do not use turpentine or other paint cleaners, which can contain oils that inhibit good adhesion.

Prop One also supplies an acid wash to complete the prep work, something that the makers of Velox discourage. After Neeves acid-cleaned the prop, he again lightly abraded it and rinsed well with water. (Prop Speed does not mention an acid-wash prep, although this would seem advisable.)

Folding props

Folding props require special attention. Neeves three-bladed folding Volvo prop needs to be completely removed to replace the sail drive anode. The prop assembly consists of 16 pieces, plus one saildrive anode, two bolts, three segmented hub anodes, and three Allen bolts. Each blade and hinge pin are marked so that the blades are returned to the exact same spot of the hub. Disassembly and re-assembly is not difficult-but does call for patience.

If this all seems excessive, five or six years ago when Neeves did not pay such close attention, most of the epoxy primer (Interprotect) and paint (Interlux Trilux) he had applied fell off within one week. With another silicone product, the paint peeled off like a plasticglove.

The actual painting with either Velox or Prop One is simple: apply the primer and topcoat following the makers instructions. These products can be professionally sprayed. Neeves used one-inch disposable paint brushes-one for primer and one for topcoat.

Velox suggest one coat of primer and two or three coats of the active topcoat. Prop One suggests two thin primer coats and one topcoat. Both require allowing at least 12 hours for the paint to dry before submerging.

One final word on application: Always remember that prop or shaft anodes must be masked and should not be painted over. Shaft anodes must also be bolted to bare, unpainted, metal, so it is best to completely assemble, mask and paint. Using Loctite to secure the anode bolts affords some piece of mind that the anode wont go anywhere.

Performance

In early 2015 we treated both sail drives and one prop with Velox and one prop with Prop One (then called Prop Gold). After about one year, Neeves beached the cat for inspection, and could detect no difference between the products. After a quick wipe-down, the boat went back into the water.

After 21 months, the two products again performed similarly. There were a few more barnacles on the Prop Gold, but they were small and isolated. Both props had soft growth that was easily wiped off. In Neeves view, both products lived up to expectations of 24-month protection, with Velox performing slightly better.

The main difference between the two products is when it comes time to re-apply, especially if you do it yourself. Most of the Velox primer was still intact, so after a powerwash and light sanding, the prop was ready for a new coat. The Prop One, on the other hand would need to be stripped back. For more on prop paints and bottom paint, check out the online version of this article, which contains links to past tests and reports.

Several past Practical Sailor tests involved antifouling paints designed for props, running gear, and aluminum saildrives. This table includes previous field trials on propellors, outdrives, and static paint panels. Only the seven paints with asterisks have been tested on props. In field trials, the difference between the foul-release coatings Prop One and Prop Speed was not distinguishable.

One of the biggest challenges with prop coatings is ensuring good adhesion, which is why some manufacturers recommend professional application. The surface must be free of grease and oil and carefully primed and prepped according to the maker’s instructions.

• It seems a shame to have to paint a shiny new prop. Even pros sometimes mistakenly paint the anode (see photo number five).
• The prop and saildrive was coated with Velox and checked after 21 months in the water (see photo number 3).
• The hull, painted with Jotun SeaQuantum Ultra was still clean after 13 months but the prop was already succumbing to soft growth. Growth was thickest at the sail drive skirt, which had been painted with Trilux 33.
• After 21 months in the water and a good power washing, the Velox coating on saildrive coating was in fair condition, but the blades had lost most of their paint, requiring a repeat of the full prep process for recoating.
• This propeller assembly has been coated with Prop Speed by “professionals” at a highly reputable yard. They also painted the anodes, which should never occur.

RELATED ARTICLES MORE FROM AUTHOR

This is an excellent article and the kind of info I have always enjoyed from PS. I plan to look deeper into these products. It appears Velox might be just the thing for my two blade flexofold prop.

Thanks for doing this testing, it is great to know ahead of time how well these expensive products work. I used Pettit Prop Coat this season and have had reasonable luck with it in the past. It seems to be very popular here in New England, perhaps because of our short seasons and cooler waters it is a decent option. Do you have any data or comparison of zinc based coatings vs those with biocides?

Also, I feel obligated to comment on photo 5, where the “professionals” made a major mistake. I had the misfortune of having my boat one of New England’s “premiere” yards this last winter and witness some of their work first hand. I was underwhelmed by the quality of their workmanship of nearly every job I saw. The takeaway is that even when you pay professionals to do a job, inspect their work. You may be surprised to see that you do better work.

I have tested a wide range of prop paints over the last few years including Prop Speed, Velox, Pettit Zinc Coat, Pettit Running Gear Guardian, and Prop Glide. None worked for more than a season due to some of the coating coming off, resulting in the need to strip and redo it every year. You can’t patch bare spots with those coatings. Last year, I stripped everything and used Rustoleum Cold Galvanizing Compound spray (at the suggestion of someone on one of the boating forums). It was easy to apply and worked great for the entire season. After power washing last fall, I just cleaned up a few spots and touched up the prop and shaft with the spray and my diver reports it is just as good as last year. Cheaper, easier and does the job!

Just a cautionary note:

Antifouls for hull and props (etc) are location and usage dependent. Most AFs require that the vessel is moved, used, and that the prop is used. Movement reduces the volume of fouling on the surface – simply the flow of water. The location also determines success of the AF – what works in one location will often not work in another, sometimes quite nearby. The type of fouling, the temperature and salinity of the water all seem to have an impact and any survey of AFs is commonly true on one location but may not be as successful in others. Similarly if you are unable to use your yacht regularly the AF will not be as successful as you hoped. This does not negate any of our AF tests – but you may need to try a couple of ‘our’ selection of ‘better’ product ts to find you what is the optimum for you.

Application is also critical – do what it says on the tin – the instructions are there for a reason! No need to ask how we know.

I used Velux this spring here in New England area. I was meticulous with the prep. Launched late May and dove on the outdrive 2 weeks ago. Drive seemed ok but folding props lost most of there paint.

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The Complete Guide to Antifouling Paint

What is antifouling.

Antifouling is a paint coating used to protect a boats hull (or areas under the waterline) from organisms that can cause harm.

How do antifouling paints work?

Antifouling paints work by releasing a range of bioactive ingredients that prevent organisms such as barnacles, slime and weeds from attaching to the vessel.

We can split fouling into two different groups: plant and animal.

• Plant: Slime (micro algae), green, red and brown weed.
• Animal: Soft bodied – bryozoa, sea squirts. Hard bodied – barnacles, mussels, tube worm etc.

What are the benefits of antifouling?

Antifouling can prolong the life of your vessel as well as improving its speed and fuel efficiency.

• Protection:  Antifoul will protect your hull from harmful fouling.
• Fuel efficiency and speed:  Keeping your hull free from fouling has a significant impact on fuel consumption and speed, because a smooth hull will have less drag and therefore use less fuel, saving you money, decreasing fuel emissions and making the vessel faster.

Before antifouling (after a jet wash)

After antifouling 

Correct application of antifoul can make yearly maintenance much easier.  After a year in the water all our colleagues’ yacht needed was a power wash which removed a small amount of fouling. As the existing antifoul was in good condition it just needed a wash and dry before applying new antifoul.

Need to know how much antifoul you need? Check our coverage guide HERE

What is “soft” and “hard” antifoul and which is right for my vessel?

Generally there are two main types of antifoul available: soft antifoul , also known as self-polishing or self-eroding antifoul, and hard antifoul , often referred to as scrubbable or burnishable antifoul. Each paint releases the biocides in different ways – the right paint for you will be determined by the waters you sail in and the speed of your vessel.

Soft antifoul (self-polishing/self eroding)

How it works:  Soft antifoul erodes slowly as the vessel moves through water so that a fresh film of biocide is always present on the hull’s surface.

Vessel suitability:  Suitable for sail boats or power boats with speeds up to 30 knots.  Any faster and the paint will erode too quickly (some paints are rated to higher speeds). The vessel needs to be used semi regularly in order to ‘polish’ the paint and reveal a fresh film of biocide.

Examples of soft antifoul are:  Hempel Tiger Xtra ,  Seajet 033 Shogun  and  International Cruiser 250 .

Hempel Tiger Xtra Antifoul

Seajet 033 Shogun Antifouling 2.5 Litre

International Cruiser 250

Hempel Cruising Performer – 2.5 Litre

Hempel Classic Antifouling – 2.5 Litre

Hard antifoul (scrubbable/burnishable)

How it works:  Hard antifoul constantly releases biocides through the paints film and doesn’t wear away like soft antifoul.

Vessel suitability:  Suitable for higher speed vessels (30 knots plus) as well as vessels that have moorings that dry out. Hard antifoul is ideal for performance racing vessels as it can be scrubbed / burnished to create a smooth hull with minimal drag.

Examples of hard antifoul are:  Hempel Hard Racing ,  Seajet 037 Coastal ,  International Ultra 300  and  VC Offshore EU.

Hempel Hard Racing Antifoul

International Ultra 300

Seajet 037 Coastal Hard Antifoul

International VC Offshore EU – 2 Litre

A third type of antifoul

There is also a third type, similar to soft antifoul, which uses Self-Polishing Copolymer Antifouling (SPC) Technology. The release of biocides are completely controlled by how fast the binder dissolves. Therefore unlike traditional self-polishing it does not require water flow to polish. An example of this is International Micron 350 .

International Micron 350

Please note: The material the hull is made from also determines which antifoul can be used.

For example, aluminium boats can only use antifoul without copper oxide in the formula, such as these paints for aluminium hulls:  International Cruiser 200, International Hard Antifouling and Seajet Emperor .

International Cruiser 200 Antifouling

International Hard Antifouling

Seajet Emperor Anitfoul

The future: biocide-free antifoul paint

Over the years we see new innovations in antifouling. An example of this is Hempel’s Silic One, a biocide free product based on silicone and hydrogel. This gives the coating surface water-like properties making it difficult for fouling organisms to attach to the hull and easy for them to be removed when the boat is in motion.

The Silic One system comprises of various primers, tie coats and top coats depending on the application you require. For information please see our Hempel Silic One Antifoul Guide .

Hempel Silic One Topcoat Antifoul Paint – Biocide Free

Hempel Silic One Tie-Coat

Hempel Silic Seal Conversion Primer

Hempel Silic One Propeller Kit

Do you need to apply a primer before using antifoul?

If you are starting from scratch with a bare hull or you’re applying on top of an unknown antifoul, you will likely need to apply a  primer  before using antifoul.

If you are starting from a bare substrate, you will need to apply an antifoul primer such as  Hempel Underwater Primer  or  International Primocon . For the best protection and adhesion you could also use an epoxy primer such as Hempel Light Primer on the bare substrate before you apply the antifoul primer.

Some primers can even be used as a barrier-coat over incompatible or unknown antifouling, providing the original antifoul is in good condition.

If the existing antifoul is not in good condition it will need to be scraped back. If you do not remove this antifoul you risk the new coat of paint peeling off.

There might only be a few places that you need to scrape off. In this instance, once you remove the paint you can patch up the area with the recommended primer first.

If you are using the same antifoul as a previous season and the hull is in a good condition, free from fouling and loose antifoul, you can just give the hull a wash and dry then apply the new paint. (However, some antifouls do require a light wet-sanding first so always check the manufacturers’ paint manual).

Antifoul for propellers, stern drives and legs

Propellers, including stern drives and legs, require specialist antifouling due to the material they are made from and the speed with which they turn. A good primer or tie-coat is also required when applying to bare metal.

Propeller treatments can be purchased in packages or individually and come in different applications including:

Hempel:  SilicOne Propeller Kit  –  Light Primer  or  Ecopower Prop Spray  –  Prop Primer Spray

Seajet:  Propeller Triple Pack (Includes Primer)

International:  Trilux Prop-O-Drev Antifoul Spray  –  Trilux Prop-O-Drev Primer Spray or Cruiser 200  –  Primocon Primer

Antifoul around the waterline (boot top)

Copper oxide based antifouling can turn green when exposed to air and salt water around the waterline. To counteract this International paints introduced  Cruiser 200 . Available in a wide range of brighter colours it can even be scrubbed or cleaned off mid-season.

Hempel also have a product called  Hard Racing Boottop  which will give a strong scrubbable antifoul in a range of bright colours.

Antifouling equipment checklist

Now you know which antifoul to purchase, what else do you need to get started? Follow our simple checklist for everything you need to carry out the task effectively and safely.

Protective Equipment, Maintenance, Painting equipment, Primer, Thinners, Antifoul

1. Protective equipment

Antifoul is toxic so  protective painting clothing  is very important. At the minimum you will need: masks, gloves, overalls, and goggles.

2. Maintenance

Sandpaper*, scrapers and cleaning products for removing fouling, slime or old antifoul. If there is damage to the hull,  marine sealants  such as gelcoat or epoxy filler are also recommended. *NEVER dry sand antifoul as the dust is toxic.

3. Painting equipment

Stock up on  painting equipment  including short to medium pile rollers, trays, brushes and masking tapes. These can be used for maintenance jobs as well as for more decorative tasks on your boat.

For repairing the hull, starting from scratch or sealing existing antifoul.

5. Thinners

Paint thinners  should generally be only used for removing and cleaning antifouling paint as well as other paints, varnishes, and epoxies from your vessel. In extreme temperatures only, can also be used to thin the antifoul.

6. Antifoul

Of course, don’t forget to stock up on  antifoul !

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