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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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The ultimate antifouling group test

A dozen of the leading antifouling paints are put to the test and rated by MBY in The Solent and the Mediterranean

The antifouling answer depends on a variety of factors including what type of boat you have, how often you use it and where you keep your boat. That’s why we’ve tried to take the guesswork out of it by looking into the science of how they work then testing a wide range of different paints in three different locations around the UK and the Mediterranean, and rating them for durability and colour fastness as well as how they performed against slime, barnacles and weed.

Types of antifouling paint

There are plenty of misconceptions when it comes to antifouling, even the question of whether to choose a hard or soft paint isn’t as straightforward as it seems, as Darren Gittens of Hempel Paint points out: “Motorboat owners often think that they need a hard paint just because their boat is capable of 30 knots but that’s not always the case. If you regularly exceed 25 knots when cruising or 80 hours total use per year, then you need a hard paint, if you don’t then you’re better off with a soft eroding paint.”

Kate Moss, new product chemist at AkzoNobel the company behind the International range of antifouling coatings, shed more light on the subject: “Most antifouling paints for motorboats are designed to use the friction of water passing over the hull to clean the growth off and erode the paint surface, but unless you take your boat out every other weekend, you could be better off with a paint for a sailing boat.”

There are five main types of antifouling paint, and what suits your boat depends on how you plan to use it. Most products use a similar combination of biocides to keep the fouling at bay so the key differences are in the structure of the paint that delivers these biocides. Over time the biocides leach out of the exposed paint surface leaving an inert coating which can no longer repel fouling. The trick is to ensure that layer of dead paint is removed either by a physical or chemical process in order to expose a fresh layer of bicocide laden paint.

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 Soft Rosin-based eroding paint

This uses a soft soluble binder that gradually dissolves in water leaving a fresh layer of paint and biocide. This means the thickness of the paint gradually reduces until it eventually disappears altogether. This type of paint suits sailing yachts and displacement motor boats but may wear out too quickly if applied to a fast planning boat that is regularly driven at speeds of 40 knots or more.

Self-Polishing paints

Self-polishing works in a very similar way to the self-eroding paint but uses a mix of soluble and insoluble glues that requires at least a tidal flow of water passing across the paint to wear it down, revealing the fresh layer beneath. This type of paint won’t go off if the boat is out of the water. Stronger binder means that it can be used on fast boats provided they don’t regularly exceed 25 knots.

CoPolymer paint replaced the notorious tin based TBT that was banned in the 1990s when it was discovered that it caused some microrganisms to change sex. Unlike the previous paints, the acrylic binder reacts to salt in the water continuously exposing a fresh layer of biocide laden paint. This means that it is not reliant on any movement of water and works regardless of whether the boat is lying idle in the marina or cruising regularly.

Hard paint is most effective the first day after launching but as the season passes the bicocides leach out and it gradually becomes less effective. If the boat is removed from the water after launch, it can also form an impermeable layer which prevents any further biocide leaching out even when launched again. Hard paint is popular on racing yachts and fast planning motor boats as it can be sanded smooth for reduced friction and won’t erode too quickly at speed. This also means it’s more prone to paint build up over the years which may need removing at some point to prevent it cracking and peeling.

Silicon paints

Rather than using biocide chemicals to stop growth, they form a super slippery surface that prevents fouling from getting a solid grip on the surface. Some growth will still appear when left unused in the marina but as soon as the boat exceeds eight knots any significant growth should wash off. They also claim to reduce friction in the water, increasing efficiency and speed. The downside is that it has to be applied to a properly prepared gel coat (any old antifouling has to be stripped off) and it can’t be painted over if you ever decide to switch back to a conventional antifouling paint. .

Paint legislation

The UK is currently in the mid-way between Mediterranean and Nordic countries in terms of legislation. Mediterranean countries are far more lax in terms of what can be used, and who can do it. The story is the opposite in the Nordic area, with some paints that are available in the UK being banned. It continues with removal too, with specialist sites that wash, drain and filter all residue being mandatory when working with antifouling. While nothing is set in stone for UK shores, it’s worth noting that changes that affect us all could be just around the corner.

What are we looking for?

In this test we are not necessarily looking for the cleanest panel at the end of the test, but one that is strong enough to withstand use in the real world, while not succumbing to growth when left in the marina. We also wanted to see how the new environmentally friendly silicone paints performed against more traditional biocide based paints. Finally, one of the biggest niggles with antifouling paint is the way the original colour can fade or change over time. This is particularly true of light colours such as white or cream which often turn green around the waterline due to the copper oxide content.

Some of the paints that we’ve tested are for professional application, and wherever that’s the case we’ve made that clear.

Greg Goulding conducts MBY’s antifouling test

How we tested them

To ensure our testing methodology was as accurate and reliable as possible we based it on advice from industry experts both before and during the test.

We picked three different locations to conduct our testing, one on the East Coast, one in the Solent and one in the Mediterranean and prepared separate boards for each area. The boards were made from marine plywood, sealed with oil-based paint to replicate the gel coat of the hull and then primed using an industry standard primer.

The board was marked out with 10 defined areas and a different antifoul paint applied to each strip. The two silicon based paints were applied to two smaller boards as we wanted to monitor these separately. The test panels were then left in our chosen locations over the 2015 season.

The two UK locations are tidal, so had a constant knot or two running past, while the Mediterranean location was a marina on the Spanish coast, giving us real world results.

Once lifted, we studied the colour change, fouling build-up and type of growth. We then ran a finger over each panel to see how securely the fouling was attached and whether it might wash off on a planing boat with regular cruising at 20 knots or more. Finally we washed each board to replicate a scrub and see how well the fouling and the paint lasted.

Static board tests are often criticised for only portraying boats that are left in the marina untouched for the entire season. However, this is still the preferred method of conventional antifouling paint manufacturers as most boats are left in the water all season, only going out a handful of times and rarely being driven hard for more than a few minutes at a time.

The big antifouling test 2023: The full results of our 18-month showdown

How to antifoul your boat: the best way to protect your hull from fouling, hempel silic one: is this the future of antifouling, latest videos, watch: parker sorrento sea trial: 50-knot cruiser with a killer aft cabin, watch: virtue v10 sea trial: €272k weekender, how to mark your anchor chain: 6 top tips from our expert, watch: galeon 560 fly sea trial – the best galeon flybridge you can buy.

• International Marine Coatings
• International Protective Coatings

Which type of antifouling should I use on my boat?

Having good antifouling protection is vital to protect your boat. But when the time comes to reapply the antifouling ready for a new season, the choices can be overwhelming. With a little knowledge, you’ll easily be able to find the right product. The key thing to understand is: do you need hard or eroding antifouling?

Hard antifouling

Hard antifoulings work by releasing biocide from the surface of the coating to deter fouling organisms. Hard antifoulings don’t really wear, but abrasive material in the water such as silt and sand may lead to a very minor reduction in the film build. Biocide leaching rate reduces over the lifetime of the product. After a few seasons, there may be a residual build-up of product that needs to be removed.

If you have a fast boat, or a fast boat that is used very regularly, then hard antifouling is usually the best product to choose. Boats moored in fresh water normally use these types as eroding antifoulings are designed to erode in salt water and may not erode sufficiently in fresh water. For those who like to race, hard products are a good option as they can be burnished or wet sanded to a smooth finish prior to racing.

Within this group there is type that contains a fluoro micro-additive to help provide a smoother faster film than a standard hard type might otherwise provide. This is favoured by keen racing types who place more importance on keeping their hulls smooth and clean rather than its antifouling performance.

Eroding antifouling

Eroding antifoulings, also known as soft or ablative antifoulings, also work by releasing biocide. However, this type of over antifouling slowly erodes in seawater eventually leaving little or no antifouling on your hull. If you wipe the hull at any time you’ll see a small cloud of product washing away. Overall, they offer very good all-round performance in a wide range of fouling conditions.

Eroding antifoulings are great for those who prefer a low maintenance option, as generally speaking there is far less accumulation of old paint on the hull after each season. However, a slow build up can still occur if excessive paint is applied at each application. This will eventually need to be removed as it may become unstable and lead to problems when new antifouling is applied.

Within this group of eroding/ablative types, there is a sub group of products known as self-polishing co-polymer antifoulings. With a more complex chemistry they offer a very controlled release of biocide and erosion level. As the paint film tends to become smoother over time, they are known as self-polishing. These types are used by larger vessel owners who require longer periods between maintenance and anyone after increased all-round performance.

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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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Practical Boat Owner

• Digital edition

The great UK antifouling test for cruising yachts

• Ben Meakins
• November 9, 2016

20 antifouling paints tested in 13 UK locations: which works best where you keep your boat?

Welcome to the biggest and most in-depth test of antifouling paints ever carried out by a magazine in the UK.

Previous tests have focused solely on one location, but as fouling conditions vary greatly between ports and harbours around the coast, we reasoned it would be of far more use to boat owners around the country if they could draw on some test results closer to home when choosing their antifouling paint from the bewildering range of options out there.

We spent two weeks painting our plywood test panels, in the process consuming 350m of masking tape, 15lt of primer and 40 (cheap) paintbrushes, not to mention the 20 antifouling paints themselves. And now, seven months and 4,400 miles of driving later, here are the results of our round-Britain antifouling test.

How we tested them

We primed our 26 test panels with International’s Interprotect Epoxy Primer before using a tie-coat primer where required and applying each of our antifoulings with the recommended number of coats (two, in most cases). We applied the paints in strips, with an 11mm unpainted strip between each paint, acting as a control surface.

We restricted the test to single-pot eroding paints in blue: these are the most popular antifoulings for cruising boats. With the paint dry, we loaded the boards into a trailer and drove them round the country, installing them facing the sun where possible and aligned with a modest tidal flow to simulate their normal usage as much as possible. We installed the boards in late March, returning in early October to remove them and inspect the results.

There were big differences between paints on the boards in terms of the amount of fouling they retained. What was telling was that even the worst-performing paints showed a massive improvement over the unprotected control surfaces – so even a cheap paint is better than nothing. However, the best performers were in a league of their own: read on to find out which paint you should choose.

Do you need antifouling?

We left the backs of our test boards as bare primer to act as a control. The good news is that without exception, every antifouling paint showed a marked improvement compared to the bare panels. Fouling differed in a big way between each of our 13 locations, from Dunstaffnage, which had minimal growth, to Hamble, which showed by far the worst. Lowestoft and Waldringfield, on the East Coast, were also bad. Whitby and Inverkip had very heavy slime, while Neyland and Caernarfon saw moderate shell and weed growth.

Click here to download a PDF of the great UK antifouling showdown as it appeared in Practical Boat Owner magazine’s January 2016 issue.

How the panels looked after more than six months at sea…

The results

North wales – caernarfon: fouling – moderate.

In Caernarfon the better paints had only light slime, while the worst-performing had heavier slime and some brown weed growth. There was no shell growth on any of the paints.

Top 5 paints 1. Seajet 033 2. Micron Extra 3. Teamac ‘D’ 4. Cruiser Uno 5. Nautix A3

South Wales – Neyland: Fouling – Moderate

Neyland had some heavy slime which had been visited by some local mullet, leaving their distinctive smear marks – also a useful test of how well the fouling was attached.

Top 5 paints 1. Hempel C.P. 2. Seajet 033 3. Micron Extra 4. Teamac ‘D’ 5. Cruiser Uno

Scotland – Inverkip: Fouling – Moderate

Inverkip’s boards showed thick slime, but none of the paints had green weed or shell growth, unlike the untreated surfaces. Some differences were evident, with Seago’s High Performance best.

Top 5 paints 1. Seago H.P. 2. Nautix A3 3. Precision P. 4. Teamac ‘D’ 5. Nautix A.P.

Scotland – Rhu: Fouling – Light-moderate

Growth in Rhu was relatively light on the better-performing paints. Seajet’s 033 was best here, with International Cruiser Uno, Teamac’s ‘D’ and Micron Extra also doing well.

Top 5 paints 1. Seajet 033 2. Int. Cruiser U 3. Teamac ‘D’ 4. Seajet 038 5. Micron Extra

Scotland – Dunstaffnage: Fouling – Light

Dunstaffnage had the coldest water of all our locations and the least slime. There was no weed or shell growth on the painted panels, and some differences between most and least effective paints.

Top 5 paints 1. Hempel C.P. 2. Precision P. 3. Seajet 038 4. Seajet 033 5. Int. Cruiser Uno

Scotland – Port Edgar: Fouling – Moderate

In Port Edgar, the boards were damaged by a tyre fender tied to the pontoon by a workboat crew, so four samples were rendered invalid, unfortunately, with paint and fouling wiped off.

Top 5 paints 1. Seajet 033 2. Micron Extra 3. Seajet 038 4. Jotun NonStop 5. Precision Prem

Northeast England – Whitby: Fouling – Heavy slime

Fouling in Whitby consisted of heavy slime. Seajet’s 033 and 038 were far and away the best, with the fouling washing off to leave a clean surface. Micron Extra was also effective, but not to the same degree.

Top 5 paints 1. Seajet 033 2. Seajet 038 3. Micron Extra 4. Cruiser Uno 5. Teamac ‘D’

East England – Lowestoft: Fouling – Moderate

The slime at Lowestoft was underpinned by some heavier growth in places. There were big differences in performance, with colonies of small shrimp inhabiting the heavier areas of slime.

Top 5 paints: 1. Seajet 038 2. Seajet 033 3. Seago H.P. 4. Hempel C.P. 5. Flag Perf. Extra

East England – Waldringfield: Fouling – Moderate

As at Whitby, Seajet’s 033 shed nearly all fouling as it was pulled out of the water, handing it best prize here. Hempel Cruising Performer, Nautix A3, and Seago’s High Performance paints also did well.

Top 5 paints 1. Seajet 033 2. Seajet 038 3. Hempel C.P. 4. Nautix A3 5. Seago H.P.

East England – Fambridge: Fouling – Moderate

In Fambridge, Seajet’s 033 and 038 again shed most slime as the boards were removed. Micron Extra was fairly clean, with Flag Performance Extra and International Cruiser Uno doing well.

Top 5 paints 1. Seajet 033 2. Seajet 038 3. Micron Extra 4. Flag Perf. Extra 5. Int. Cruiser Uno

South Coast – Chichester: Fouling – Moderate

In Chichester, Seajet’s 033 was by far the cleanest, coming out almost slime-free. Micron Extra was a close second. Seajet 038 and Teamac ‘D’ were next best, with Precision Premium also doing well.

Top 5 paints 1. Seajet 033 2. Micron Extra 3. Seajet 038 4. Teamac ‘D’ 5. Precision Prem.

South Coast – Hamble: Fouling – Moderate

Seajet’s 038 was best in the fast-flowing mouth of the Hamble, with their 033 product not far behind. Micron Extra was relatively clean, as was Teamac’s D, with Jotun NonStop also moderately successful.

Top 5 paints 1. Seajet 038 2. Seajet 033 3. Micron Extra 4. Teamac ‘D’ 5. Jotun NonStop

South West – Plymouth: Fouling – Moderate

Seajet’s 033 performed best at Plymouth Yacht Haven, with 038 also doing well. Micron Extra was also a strong performer, with the same company’s Cruiser Uno and Jotun’s NonStop also doing well.

Top 5 paints 1. Seajet 033 2. Seajet 038 3. Micron Extra 4. Int. Cruiser Uno 5. Jotun NonStop

The PBO verdict

Boards were submerged during the summer months

This is the biggest test we’ve ever carried out at PBO, with a significant investment of time, money and effort involved in buying, priming, painting, delivering and installing the test boards.

We were careful to install the panels as similarly in orientation, location and tidal characteristics as possible – facing the sun, and aligned to the tide to simulate a boat’s mooring and occasional use.

We were fortunate that only one set of panels suffered damage (in Port Edgar, where a tyre fender was tied on in front of the board, damaging the paint and removing the fouling from a few of the panels).

Our host locations kindly monitored the boards and their growth throughout the year. When we took them out, in early October, the water was at its warmest and the fouling greatest. Any later and the fouling would have begun to drop off as the water cooled.

Of course, our static panels represent a ‘worst-case’ scenario – that your boat doesn’t move all year. The more you use her, the better your antifouling will perform, and the less the fouling will adhere.

Some interesting results

A board from Whitby as removed, showing how the slime ran off the two Seajet products, 038 and 033

With the results in, the 26 panels, 20 paints and 13 locations have generated a lot of data.

Sifting through has shown up some interesting results. The most telling of all is that every paint tested showed a big improvement in fouling when compared to the control areas, which had heavy weed, shell and kelp growth. None of the paints had any barnacles or other shell growth, or any long fronds of weed – except in some cases along the waterline.

While no single paint kept everything fouling-free in all areas, what particularly surprised us was the dominance of one paint – Seajet’s 033 Shogun was best in eight of our areas, with the company’s 038, due to be released in 2016, also doing well.

These paints shed slime and other fouling so effectively in many places that when pulled out of the water, they appeared clear.

Other paints also performed reasonably well. International’s Micron Extra was a comfortably one of the top paints all around the country. Other good performers included Teamac Antifouling D plus , made by an independent family business located in the north-east, Precision Premium, also made by Teamac, and Nautix’s A3. Seago High Performance also performed well in places. Hempel’s Cruising Performer and Jotun’s NonStop did well in some areas of the country. Boero’s Mistral NF had some reasonable results, and Flag Performance Extra did well on the East Coast.

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.

Increased regulation.

Of course, most boat owners won’t be interested in which brand is best all around the country: most boats stay put in their home port for most of the season, which is why it’s best to look at the results for your location, or the nearest port to your own.

It’s reassuring that the better paints on test proved mostly effective in keeping fouling at bay, as manufacturers have had to deal with increased regulation – especially the EU’s Biocidal Products Directive, which has led to tweaks and changes in antifouling products.

Cost is another interesting factor. Paints seem to split into two camps – around £40-50 per 2.5lt tin and around £100 per tin. The circa £100 camp tended to do better than the circa £50 camp – the more expensive bracket, which often has greater concentrations of copper and other biocides, is likely to be more effective.

As published in Practical Boat Owner magazine’s January 2016 issue. Prices correct at the time of going to press.

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By using something every skipper has on board

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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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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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Comprehensive Buying Guide: Best Antifouling Paint

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If you berth your boat in the water for at least half of the year, keeping the hull free from excessive growth of the marine organism is crucial for its performance. It is where the use of quality antifouling paints comes in the picture. Using quality antifouling paints is essential to protect your boat from water damage. It also it reduces fuel costs.

If you are a boat driver, this preventative measure should be your priority. According to boat experts, a clean hull is fast, efficient and safe . However, a fouled bottom reduces your boat’s maneuverability, speed and most importantly cost you more fuel price.

Moreover, your boat needs protection from marine organisms such as zebra mussels and barnacles. The planktons in the water are equally detrimental for your boat that includes algae, weed, and slime.

All these planktons adhere themselves to the boat’s hull and damage its paint. Antifouling paints use toxic biocide- a metal dissipation to prevent vexing critters like planktons from adhering on the hull.

Unlike traditional protection methods, when people used copper sheaths as a protective coating to save hulls, antifouling paints use cuprous oxide. The copper compound is still the primary biocide mixed into paints for marine growth prevention.

There are a plethora of choices when it comes to picking up suitable antifouling paints. Typically, the paint choice depends on the boater’s region and local marina.

Plus, how much you use your boat and the paint you used in the past, are also important factors to consider. If you pay attention to these factors, you may face compatibility problems in various color formulations.

In general, there are some exceptions when you talk about purchasing the right antifouling color to paint hulls. For example, you can apply softer paints over hard paints but, you should not recoat vinyl paints over the same paint.

The buying guide, in this regard, has the comparison of best antifouling paints to help you choose the best product for your boat. All three products are popular to protect your boat from corrosion that could lead to hull damage.

Best Antifouling Paints

Let’s take a look on our recommendations for the best antifouling paints:

Winner: Total Boat Underdog Boat Bottom Paint

If you are looking for a quality solvent-based antifouling paint, then Total Boat Underdog antifouling paint is your product. The single-season pain comes with outstanding protection qualities. With its ablative action, it works effectively, and you can use it on a regular basis.

• Comes with excellent antifouling protection
• Cost-effective
• Easy-to-apply and dries fast
• Resists abrasion
• Ablative technology keeps fresh biocide on surface
• Durable and withstands trailering
• Available in different colors
• The paint gets thick and difficult to roll on

Many boat experts have recommended this quality boat paint after extensive testing. Totalboat Underdog provides unparalleled protection against antifouling pests and barnacles in any water condition.

The powerful paint formula releases around 25 percent copper content. It is a controlled rate that keeps the soft and dense growth of grasses, algae, and slime at bay.

The affordable price of Total boat paint is unheard of the figure in the antifouling paint industry. The buyers are delighted to purchase an inexpensive yet quality product that ensures season-long protection against fouling organisms.

Source: totalboat.com

This antifouling paint gradually wears away when boating voyages in the water, offering optimal protection. The ablative formula of the paint ensures to keep a fresh coat of biocide on the surface to combat bothersome marine growth.

Moreover, Total boat paint is beneficial for the people who are regular boaters. It is the best antifouling paint for fiberglass. Its excellent adhesion ability on fiberglass and wood is what makes it an ideal paint for short-season boat drivers. It has unbeatable coverage characteristics and adhesive qualities that protect your boat for a long time.

The durable finishing can withstand trailering and harsh weather conditions. A cleaned and the sanded water surface is an ideal condition for Total boat paint. Plus, preparing it is not a lengthy affair; all you need to do is stir, and paint with a roller or brush.

You do not need to wait long for Underdog to get dry. If the temperature is moderate, drying takes less than an hour. You can overcoat it and get your boat ready to launch.

Totalboat Underdog paint offers proven performance regarding thwarting algae and barnacles. Mainly, if you use your boat frequently, it is hard to get ablative and durable finish stands like Underdog paints.

However, if your boat use is occasional and it sits stagnant in water, you can reactivate Underdog’s antifouling features with light scrubbing. Hence, it is the best freshwater antifouling paint and a smart choice to protect your watercraft from a marine organism.

Runner-Up: Rust-Oleum Marine Flat Boat Antifouling Paint

Rust-Oleum Marine Flat is one of the products that received some best antifouling paint reviews. This product is an ideal option for you if you are planning to launch your yacht after a long time. It creates a durable protective coating on the bottom hull to prevent algae, barnacles’ build-up and other marine growth.

• Provides the best protection to fiberglass surfaces
• Has a smooth, glossy finish
• Works best in moderate and mild fouling conditions
• Slow release of copper prevents fouling
• Comes with an oil-based  advance formula for self-leveling
• The seal on can comes off quickly and causes paint leakage

Many boat experts appreciated the adhesive qualities of Rust-Oleum Marine Flat. Based on its excellent performance , boaters consider it the best outdrive antifouling paint. Ideal for steel surfaces, Rust-Oleum paint effectively prevents fouling from growing beneath the waterline of your boat.

What stands out with its all these qualities is the copper-based coating. It covers the entire hull bottom with its hard coating. That is why it releases slowly to ensure maximum prevention from marine growth.

Plus, Rust-Oleum paint is suitable for moderate and mild antifouling conditions. Whether it is salt water or fresh water, Rust-Oleum provides unparallel protection.

Source: rustoleum.com

Furthermore, the excellent product contains around 45 percent of cuprous oxide that makes it one of the hardest antifouling paints. With its tendency of copper release, it has become an excellent formula for trailered boats. However, using it on the aluminum surfaces is not safe. It might give you unfavorable results if copper reacts with aluminum.

For the best antifouling performance, launching painted boats within sixty days is ideal. You do not need priming on the fiberglass or on the surfaces you have painted in the past. If you are applying paint on bare wood, you need only 10 percent of mineral spirit to mix in the Marine flat antifouling paint.

Hence, there is no denying that Rust-Oleum is not only the best antifouling paint for saltwater but also a superior protector for your watercraft. It is a high-performance product with it hard finishing. It provides a smooth flat sheen-particularly for aged antifouling coats.

Alternative: Interlux Trilux 33 Aerosol Antifouling Paint 16 Oz

Are you looking for the best antifouling spray paint?   Interlux Trilux is a high-quality antifouling paint- particularly formulated for aluminum boats. With its tin-free formulation, Interlux Trilux has outnumbered its competitors in the antifouling paint industry.

• Provides long-lasting protection
• Comes with Biolux technology
• Perfect for aluminum boats
• Available in bright colors
• Easy cleaning and durable
• It requires  professional expertise to use spray paint

The product has a high-end paint formula to provide full strength to hull bottom to withstand any water condition.

It has an active protection formula that makes it a perfect choice for your outboards, outdrives, and aluminum boats. Available in bright colors, the Interlux spray paint invigorates the color scheme of your boat.

The incorporated Biolux technology sets this spray paint apart from the rest of antifouling paints. Not only does this pain gives your yacht a beautiful bright color, but also ensure improved control over marine growth.

Interlux Trilux antifouling paint comes with some revolutionary features. It has replaced the traditional liquid paints such as Micron 33 because of its Biolux technology. Protecting underwater hulls and other parts of the boats,

Source: ebay.com

Trilux 33 is suitable for brackish water, fresh water, and salt water. If you cannot afford spray painting, you can apply the paint with roller or brush.

However, spray application requires you to have the professional expertise to apply paints. Safety equipment like professional applicators and full-face shields are must to use for spray painting. The paint has a highly effective formula that suits different material. You can use it with wood, underwater metals, and fiberglass.

Slow polishing in Trilux 33 is another standout feature that makes it ideal for robust, fast and frequently used watercraft. No longer do you need to worry about galvanic corrosion with Trilux 33 as it contains cuprous thiocyanate. It also makes paint super absorbent.

Unlike other antifouling paints, Trilus 33 does not lose its effectiveness when you expose it to air. This feature makes it perfect for trailered boats. The new formula of antifouling paint impresses buyers. According to them, there is a significant reduction in marine growth on the bottom hull of their boats.

Thus, purchasing Interlux Trilux 33 is undeniably an ideal option if you want to experience high performance.

Features To Look Out For When Buying

Buying a quality antifouling paint is essential to maintain your boat’s efficiency . You need to consider the following elements before you purchase antifouling paint.

Type of Surface

Determining whether your boat has wood, aluminum or fiberglass surface will help you choose the right antifouling paint. There are several antifouling paints, which only work best with fiberglass surfaces. The paint reacts unfavorably on aluminum or wood surfaces.

For example, choosing paints with high cuprous oxide for the aluminum surface can be harmful.

Type Of Fouling Conditions

Understanding different types of fouling conditions is an important aspect to consider before you purchase antifouling paint. It can be algae, barnacles or mussels or any other marine organism that damage the hull of your boat.

Once you determine the type of fouling condition, you will be able to choose suitable antifouling paint to address the problem.

Recoat Time/Launch Time

It is another critical factor that you should consider. There are paints with specific launch time limit. For example, paints like Rust-Oleum performs better if launched within sixty days. Plus, some antifouling paints need recoating every fourth week.

Fresh Or Saltwater

Assessing the suitability of antifouling paints in different water types is essential. Make sure to check to foul resistance ability of your paint in salt or fresh water before purchasing it.

If you exclusively use your boat in freshwater, your boat likely to develop a good amount of algae slimes. You need to look out for antifouling paint with high biocide quantity to deal with this efficiently.

Can You Apply It Over Other Coatings?

There is no doubt that bottom painting of a boat is a technical task. It is essential for good adhesion that the hull you are painting has a clean surface. Plus, if the previous coating has flakes and cracks, you will find recoating difficult.

So compatibility with the base coat is an important feature you should look out for buying antifouling paint. Make sure to check the compatibility of your chosen antifouling paint or with other coatings.

Overall, you cannot deny the importance of knowing the critical steps to paint the hull bottom of your boat. You need to consider several other factors like fouling condition, water type, launching and recoating time before applying paint.

The weather conditions in your region are another significant factor you should heed before choosing the right paint formula. It is important that you paint your boat’s hull bottom before hauling out in the next season.

If you use multi-season ablative, it can protect your boat from massive damage. Thus, the buying guide answers your all questions regarding choosing the right antifouling paint for your boat.

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Yachting Monthly

• Digital edition

Propeller antifouling tested: Prop Defender

• Theo Stocker
• July 7, 2021

How well does propeller antifouling work? Yachting Monthly editor Theo Stocker tests Prop Defender over a full season to find out

Preventing fouling on your prop can help cut down on fuel use

Protecting a propeller from fouling is not easy, thanks to high prop speeds, but infrequent use.

There are three possible approaches to take; polished metal, slippery silicone based coatings, or biocidal antifoul s.

By the end of the previous season, the generous fouling on the two-bladed fixed bronze propeller on our Sadler 29, Pasque , was costing us 1.5 knots under engine.

A season with Prop Defender yielded significant fouling from coral worm. Credit: Theo Stocker

Last season, it was time to try something else and we decided to put a new glass-reinforced, silicone-based and hydrophobic product to the test.

Prop Defender creates a slippery surface to which fouling will struggle to stick, and should slip off when it does.

It uses non-aggressive primers, making it suitable for all metals.

Although coral worm grew after a season with Prop Defender applied to the propeller, it was washed off easily with a pressure washer. Credit: Theo Stocker

It also contains no toxins, solvents, biocides or VOCs.

Application of the original product I tested is in three stages and proved to be pretty straightforward, though needs to be done carefully.

Start with a totally clean propeller before rubbing in the degreasing preparation paste with 180 glass paper pad.

Continues below…

Ultrasonic Antifouling Test

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Next, scrub clean using the supplied detergent, and rinse off with fresh water.

Leave it to dry and don’t touch the metal with bare hands, as this can reintroduce grease.

I then applied the top coat with a brush – it needs 24 hours before it goes in the water and three days before use.

The company has since updated the product so it now has a two-stage hydrophobic top coat, which it claims makes the finish even more hard-wearing and slippery.

Verdict on Prop Defender

Our boat was in the water for a short six months this year and on the whole I was pleased with the performance of Prop Defender.

Our speed reduction from fouling was kept to a maximum of half a knot under engine, which is a good deal better than with bare metal.

During the main summer months, there was very little fouling to spot.

When we pulled the boat out of the water in late October, after a period of little use, there was very little weed or other growth, though more tenacious coral worm had been able to stick, and any other fouling had grown on this, rather than the metal.

Overall, it wasn’t a perfect solution, but a significant improvement on last season.

Specifications:

Price: £74.95 Coverage: 100ml or 2 applications for 24in prop Includes: Prep paste, detergent, top coast x 2, stirrers, glass paper, gloves, brushes Contact: www.prop-defender.com

Other propeller antifouling on the market

Hempel Ecopower Prop

A biocide-free spray, Ecopower Prop is used as a coating for propellers making it difficult for fouling to fully attach thus making it easy to dislodge and remove when cleaning.

It has a ‘self-renewing effect throughout the season’, and needs to be applied over a primer.

Price: From £22.99

Buy it now at Amazon (UK)

Buy in now at eBay (UK)

Buy it now at eBay (US)

Marlin Velox Plus Propeller Antifouling

A hard biocidal antifoul paint suitable for all metal types.

The active ingredient is zinc pyrithione, combined with soluble and insoluble resins to offer high adhesion.

It can be overcoated each season.

Price: From £43.95

Buy it now from Amazon (UK)

OceanMax Propspeed

Propspeed claims to be ‘the original propeller and running gear coating system’.

It’s a silicone based topcoat that creates an extremely slippery surface.

Manufacturer Oceanmax recommends that it is applied by a professional applicator.

Price: From £349.99

Buy it now from eBay (UK)

Buy it now from eBay (US)

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.

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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.

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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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