Boat Painting

Preparing Your Boat for Boat Painting

boat painting

A new paint job protects your boat, makes it look great, and easier to clean. It’s a worthwhile investment. Start with the manufacturer’s instructions. Most topside paints can be rolled or brushed on, but some require specific thinners or have other requirements for application.

Many racing sailboats use thin-film paints that contain a PTFE finish and biocides to keep marine growth from adhering to the hull. These can be used in fresh or salt water.  


As with all paint jobs, prep is the most important part of painting a boat. If you don’t prepare your boat properly, you will end up with a poor-quality finish that may not last. This is especially true for bottom paint, which needs to be properly applied and thoroughly dry before your boat can be launched.

One of the most important parts of preparation for bottom paint is removing any hardware that is on your boat’s hull. This can be time-consuming, but it is essential to ensure that you have a smooth and even surface for your paint job. If you have hardware that cannot be removed, you will need to carefully mask it and use a filler to cover the area.

After removing the hardware, you should then thoroughly wash your boat. This will help remove any slime or dirt that is stuck to the bottom of your boat and prevent a smooth, even surface for your paint. You should also try to make sure that your boat is free of any barnacles or hard growth. This is easiest to do shortly after removing the boat from the water.

It is also a good idea to de-wax your boat before you start sanding. This is because a little bit of wax can prevent your bottom paint from adhering to the fiberglass, so you need to be thorough with this step. You can use either acetone or a dedicated de-waxer to get the job done.

Another thing to consider when preparing for a bottom paint job is the weather. If you can, it is best to apply the paint on a day that is dry and cool. This will reduce the potential for nature-induced problems, such as rain or wind, that could ruin your new paint job.

When you are ready to begin applying your primer, be sure to follow the manufacturer’s instructions to a T. Most marine coatings require at least two coats, with a light sanding between each application. Make sure that you apply the primer evenly and let each coat dry completely before sanding again and applying the second coat.


A boat’s paint requires a different type of primer than most other surfaces. Marine epoxy primers are a versatile compound with excellent filling and paint adhesion properties. They can be used both above and below a boats waterline and work well on fiberglass vessels as well as aluminum or steel substrates.

Whether the primer is a topside or bottomcoat, it is important to follow the manufacturer’s recommendations for use. The primer may be a key to a successful antifouling paint system, and it will improve the adhesion of future coats.

Before you begin priming, you’ll want to make sure your surface is free from dirt, debris and other contaminants. You’ll also want to make sure that the area you’re working in is well-ventilated. Sanding and painting can produce a lot of sawdust and fumes that can be hazardous to your health if not properly ventilated. For best results, work outside or in a well-ventilated garage or shed.

Once your surface is clean, it’s time to prep for a fresh coat of paint. First, you’ll need to wash your boat thoroughly to remove any waxy coating that may have built up. This is necessary because the wax will prevent your new primer and paint from bonding to the surface. A good scrub with rough sponges will get the job done; you’ll know you’re finished when you can no longer feel any residue or waxy feeling on your surface.

Next, you’ll need to sand your surface for a smooth finish. Use 120-grit sandpaper to achieve this, and be sure to sand both the high and low areas. Once you’ve sanded, wash your surface again with solvent to remove any residual debris and allow it to dry completely before moving on.

If your boat is left in the water for long periods of time, you might want to consider a barrier coat for the bottom of your vessel. These epoxy undercoats provide a moisture-resistant surface that greatly decreases the risk of gelcoat blistering. Check out West Advisor’s article on Epoxy Barrier Coats to learn more.


While proper boat maintenance goes a long way toward keeping your pride and joy looking new, it’s not possible to stop the inevitable aging process. If your boat is beginning to look a little rough around the edges, a fresh coat of paint is all it takes to take it back to its original glory. A new paint job also helps protect the hull from damage and makes it easier to keep clean. While painting a boat is a fairly time-consuming project, it’s one that anyone can tackle with a little know-how and preparation.

Before you can begin painting, you’ll need to thoroughly wash the hull. Seaweed, sand and dirt can all stick to the paint and eventually cause it to chip or peel away. Using a pressure hose and rags, scrub down the entire hull surface. You’ll want to be especially thorough in areas that are most exposed to water, such as the bow, rudder and leading edge of the keel.

Once the hull is clean, you’ll need to de-wax and sand it before applying your bottom paint. If you’re using a new gel coat, skip this step. However, if you’re painting over old bottom paint or ablatives, you will need to do the same prep work.

The most popular type of antifouling paint is a hard modified epoxy product. These paints have a very high performance and are easy to apply. They are durable and look great, although they do require some sanding and buffing between coats. These paints are typically sprayed and require special solvents for cleaning the spray gun and brushes.

Ablative and copolymer products are two other types of antifouling paints that are commonly used. These paints release their biocide at a controlled rate, so they wear away or “ablate” at a much slower rate than hard modified epoxy paints. This slow degradation reduces the amount of time between haulouts and can significantly extend a paint’s life.

Lastly, there are two-part polyurethane paints that provide the best protection and appearance of all the different options. These are more expensive, but they last longer than other types of paint. Polyurethanes need specialized application equipment and specific temperature and humidity conditions for best results. When applied properly, these paints can outshine the hull’s original gel coat.


If the previous steps were done well, you should be ready to apply a few coats of finish paint to your boat. Be sure to follow the manufacturer’s instructions on curing times, as these can vary. These cure times are designed to give the new paint time to bond to the fiberglass and allow it to withstand the water for years to come.

While you’re waiting for the paint to dry, take this opportunity to clean up any splatters, drips or missed areas. This will help ensure that the next layer of paint adheres better, and will also help prevent rust or corrosion on your hardware.

One-Part Polyurethane Paint

The simplest way to paint your boat is with one-part polyurethane, which will provide a tough, durable, long-lasting finish that’s easy to work with. These paints are great for the topsides of your boat, and you can get them in a variety of colors. Polyurethanes also have the advantage of being very resistant to moisture and abrasion, and they can resist direct and reflected sunlight, helping your boat maintain its color and integrity for a longer period of time.

For a more professional finish, you can use two-part polyurethane. These paints are much more labor-intensive than one-part, and they require a special epoxy primer and specific temperature and humidity levels to be applied correctly. However, they look amazing and last a very long time.

Whether you choose one or two-part polyurethane, be sure to thoroughly stir the paint before applying. The copper in these paints can settle into a thick mass at the bottom of the can, and stirring it back into solution is a pain. This will also give you the opportunity to make any adjustments in thickness or consistency that may be needed for your particular application.

While you’re working, carefully tape off any hardware or areas of the boat that are not getting painted. Be sure to tape very closely around thru-hull fittings and eyes, as well as upholstery and electronics. Taking the time to do this will make your job much easier, and it will minimize the amount of clean up you have to do once your boat’s final coat is on.