Boats are exposed to a variety of elements and objects — water and all the vegetation and organisms that come with it, UV rays of the sun, extreme temperatures, sand, trailers, docks and more. It’s no surprise the paint on boats begins to crack and fade over time. When this happens, a fresh coat of paint can make a world of difference, but only if it’s done properly.
With the exposure to all these elements and objects, boats end up with peeling paint and dents. Simply painting over this uneven, damaged surface will leave you with an ugly paint job that is susceptible to peeling — and an expensive bill to fix it. They key to getting your boat like new is in the preparation. According to Sailing World, 75 percent of a successful paint job is the preparation. That means taking time to inspect your boat for problem areas, scrape off peeling paint, sanding, feathering, filling and priming — all before you apply your first coat of paint.
What you’ll need to get started:
- Mask
- Protective glasses
- Tape
- Tack cloth/rag
- Putty knife
- Dewaxing solvent
- Primer
- Epoxy filler
- Random-orbital sander or finishing sander
- 80- to 120-grit sandpaper
- Paint roller
- Paintbrush
- Topside boat paint
- Boat bottom paint
How to Prepare a Boat’s Hull for Painting
If you’ve been wondering how to prepare a boat for painting, there’s no short answer. The reality is the actual painting of your boat takes the least amount of time — the preparation is the time-consuming part. However, with the right preparation, your coat of paint will last several years and make your boat look like new. So how do you paint a boat hull?
How to Choose an Environment to Prepare and Paint Your Boat
The preparation and painting of your boat begins with choosing a place to prep and paint. While the location may not seem like a big deal, this process is an investment of time and money, and the environment you choose can have a significant impact on the result. Here are a few of our recommendations for determining the perfect location.
- Choose a sheltered area.
The ideal location for both preparing and painting your boat is under some sort of shelter. A shed is the best option, but you can also create your own shelter from tarps or plastic sheeting if a shed or other structure isn’t available. The ultimate goal is to have an area free of any windblown debris. Protection from the elements, including the sun, is another perk of prepping and painting your boat in a sheltered area.
- Make sure the area is well-ventilated.
The ideal location for both preparing and painting your boat is under some shelter. A shed is the best option, but you can also create your shelter from tarps or plastic sheeting if a shed or other structure isn’t available. The ultimate goal is to have an area free of any windblown debris. Protection from the elements, including the sun, is another perk of prepping and painting your boat in a sheltered area.
- Pick a day with a low chance of rain.
While protection from the elements and debris is ideal, it’s also important to balance that protection with ventilation. Even before you begin priming and painting your boat, you’ll be sanding and using solvents, both of which require a well-ventilated area to keep you safe from sawdust and fumes.
- Plan to paint mid- to late-morning or mid-afternoon.
Moisture isn’t just present on a rainy day, but also in the dew in mornings and evenings. Avoid painting first thing in the morning or last thing in the evening for these reasons. It’s also wise to avoid high noon, when the sun is at its peak for heat. Both of these extremes will impact paint drying time, so it’s best to plan accordingly and paint mid- to late-morning or in mid-afternoon — after the dew has evaporated. Save noontime for your lunch break.
How to Prepare a Boat for Painting
While getting a fresh coat of paint on your boat is the ultimate goal, the preparation is going to take the longest amount of time. If you skimp on the prep work, it will show in your paint job. Here’s how to do it right:
- Clean the boat.
The very first step is to thoroughly clean your boat. This is easiest to do shortly after you remove the boat from the water, when it’s still wet. To ensure you get a deep clean, you should use a combination of a pressure washer or high-pressure hose, scraper and rags.
Make sure you remove everything from the surface of your boat, including barnacles and other hard growth that may have attached to your boat. You want to start with a clean slate — anything like slime, dirt, sand or hard growth that is stuck on your boat will get in the way of a smooth paint job.
- Remove the hardware.
We know removing every single piece of hardware possible is time-consuming, but it’s the only way to ensure the best possible paint job. This includes any aluminum siding on your boat. If there are pieces of hardware you absolutely cannot remove, you can carefully cover them with painter’s tape.
If you’re wondering why you can’t just mask and paint around all the hardware, the answer is that the paint will often be on the piece of hardware and the boat. Over time, that paint will be much more likely to crack, welcoming in water and debris, which results in flaking and peeling paint and creates more work for you in the end. Do yourself a favor and dedicate the time to removing the hardware up front to avoid problems down the road.
- Strip the wax coating.
Almost all boats have a wax finish on them. Primer or paint won’t adhere to wax, so you must remove it before you apply to prevent headaches. If you aren’t sure whether or not your boat has a wax finish, usually simply running a finger along the surface of the boat will give you the answer.
Boat solvents, with the help of rough sponges, can help you get rid of any bit of wax that is on your boat. It may take a few rounds of scrubbing — you’re only finished when there’s absolutely no waxy feeling left on your boat.
- Tape off an area to paint.
Marking off the area you’re going to prime and paint is just as important as choosing the right kind of tape. If you pick the wrong tape, you’ll be spending a lot of time removing the tape and/or the residue it leaves behind. Invest in a “long-mask” tape, like 3M’s 2090 Scotch Blue Painter’s Tape, which can handle the UV rays, but also can be left on a surface for several days.
- Mark trouble spots with tape.
Once you have marked the area you’re going to paint first, it’s time to inspect that area for trouble spots. What exactly is a “trouble spot”? Look for dents, dings and places where the paint is chipped and/or peeling. Mark them all with a small piece of tape so when you’re finished, you can see all of the trouble areas that need to be addressed.
- Scrape off peeling paint.
Peeling paint isn’t going to help your new paint job. Air and water have already made their way between the paint and the surface of the boat, which means it will continue to peel even with a fresh coat of primer and paint on top of it. To ensure an even, well-adhered coat of fresh primer and paint, remove all peeling paint. If you’re applying a different type of paint than the old paint, you’ll need to scrape and sand off all the pre-existing paint.
The best way to do this is to scrape the paint off with a sharp putty knife, making sure you keep the edge of the knife parallel to the surface. Cutting into the surface will result in creating new dents, and ultimately, more work.
- Sand and feather.
Once you’ve scraped off all of the peeling paint, it’s time to sand and feather the edges around those areas to get the surface as smooth as possible. Put on your mask and protective glasses to avoid inhaling toxic paint chips and sawdust. Use a random-orbit or finishing sander, like our Mirka Pneumatic Random Orbital Finishing Sander, but never a belt sander, which is sure to do more damage than good. You’ll want a rough sandpaper to get the job done — somewhere between 80- and 100-grit.Once you’ve scraped off all of the peeling paint, it’s time to sand and feather the edges around those areas to get the surface as smooth as possible. Put on your mask and protective glasses to avoid inhaling toxic paint chips and sawdust. Use a random-orbit or finishing sander, like our Mirka Pneumatic Random Orbital Finishing Sander, but never a belt sander, which is sure to do more damage than good. You’ll want a rough sandpaper to get the job done — somewhere between 80- and 100-grit.
The particular type of sandpaper you choose depends on the boat’s material. We recommend Mirka Abranet sandpaper, which relies on flexible fabrics with breathable, net-mesh designs. Breathable means this sheet provides dust-free sanding for materials ranging from aluminum to carbon steel. If you’re working with wood, Mirka Bulldog Gold Proflex Sandpaper has aluminum oxide grain, which gives you a good cut and excellent scratch pattern.
How to Prime a Boat
Once you’ve prepared the surface and have a clean, smooth surface free of peeling paint, you’re ready to prime the boat. While our directions are for two coats of primer, please note you may need to repeat filling and sanding a few times, depending on the number of dents and low spots you have.
- Wipe surface with a tack cloth.
Regardless of whether you use dust-free sandpaper and/or a vacuum to collect the dust, you still want to follow your sanding and feathering with a tack cloth. This cloth has just enough of a tacky finish on it to remove any remaining loose particles, leaving you with a flawless finish.
- Apply the first coat of primer.
Once you’ve wiped down the entire area with a tack cloth, it’s time to apply your first coat of primer. Resist the urge to apply a thick coat — instead, paint on just enough to cover the surface of the area you’re going to paint. Let the primer dry. Make sure you follow the manufacturer’s instructions for drying time and time between coats. Don’t panic if you can see uneven spots on the surface — we’ll address that in the next step.
- Fill low spots with epoxy.
Inevitably, you’ll notice uneven spots on the surface — maybe left over from dents or peeling paint you tried to sand out. Once the primer has dried, it’s time to touch up these low spots with epoxy. Using your putty knife, apply the epoxy and do your best to evenly spread it over the low areas, creating a surface that’s as even as possible. Then, let the epoxy cure.
- Lightly sand.
Once the epoxy has cured, you want to lightly sand the area with a higher-grit sandpaper, something close to 320-grit, to get a completely smooth surface. We recommend using Mirka Waterproof Sanding Sheets, specifically designed for wet sanding — just in case the epoxy isn’t 100 percent cured, this sandpaper will still get the job done without worrying about creating a mess.
- Wipe with a tack cloth.
Once you’ve sanded the epoxy, wipe the entire area down with a tack cloth. You should reveal a smooth surface, free of low spots and dents. If you discover the area is completely smooth, move on to the next step. If you still see some low spots that could be improved, fill them with epoxy and repeat until you have a smooth surface.
- Apply a final coat of primer.
When you finally have a smooth surface, apply your final coat of primer and remove the tape while the primer is still wet. Let it dry — again, making sure you follow the manufacturer’s instructions for drying time and time between priming and painting. This final coat of primer should even out the color over the already seamless surface, proving your preparation is complete and you are finally ready to paint your boat.
How to Paint a Boat
The preparation is officially complete once the final coat of primer has dried. Now, it’s time for the final set of steps to complete your project — painting your boat.
- Wipe with a tack cloth.
Once your primer has dried, wipe the entire surface down with a tack cloth, removing any loose dust or dirt that has accumulated.
- Tape the edges.
Once you’ve wiped down the entire area, tape the waterline and along the top edge of the topside. Again, be sure to use long-mask tape. In addition to taping the waterline, consider covering the boat bottom or antifouling area.
- Review paint manufacturer’s instructions.
Since there are different types of topside boat paints, it’s important to remember to consult the manufacturer’s instructions before you begin painting. Some paints require thinner or have other specific mixing instructions. You want to make sure you’re following every piece of advice the manufacturer gives you before you begin to apply the first coat of paint.
- Brush or roll on the first coat of paint.
Once you’re certain you have read the manufacturer’s instructions and have mixed the paint accordingly, it’s time to apply your first coat. The majority of topside paints can be rolled or brushed on, but again, the deciding factor should be whatever the manufacturer recommends. Begin by rolling or brushing perpendicular to the waterline, making sure to take shorter strokes and covering only a small area at a time. Then, brush or roll parallel to the waterline to finish. Let the paint dry and apply additional coats per the manufacturer’s instructions.
- Remove the tape.
Before the final coat of paint is dry, remove the tape. Waiting until the final coat is dry puts you at a higher risk of peeling paint along with the tape, causing you to have to start some of the preparing and painting processes all over again.
Painting the Deck and Bottom of the Boat
While there are a lot of similarities when it comes to preparing and painting the deck and bottom of your boat, there are also some notable differences.
The deck of your boat is likely a combination of fiberglass and non-skid surfaces. On the deck, it may not be possible to remove several pieces of hardware. In that case, you should meticulously tape off all the hardware and cover upholstery and electronics. Aside from that, the preparation and painting are very much the same, except for the non-skid surfaces. When these areas are damaged, you have two options — stick an entirely new non-skid surface over them, or paint them with a paint that contains a non-skid compound.
The bottom of your boat has maximum exposure to the water and all the growth and organisms living in it — so the paint selection for the bottom of your boat is different. What is bottom paint on a boat? Bottom paints contain a biocide, often in the form of copper, that is meant to continuously slowly fade away to expose more of the biocide, which prevents barnacles and other marine growth. For more information on bottom painting a boat, visit our how-to guide for painting the bottom of a boat.
Paint Your Boat Propellers and Running Gear
We’ve covered the topsides, deck and bottom of a boat, but should you paint your boat propellers and running gear? While the appearance of your propeller and running gear may not be a high priority, the performance is a top priority.
If you’ve been wondering how to keep marine growth from fouling your propellers, painting it just might be the answer. Applying a foul release coating to these areas can improve performance and protect your boat propellers by preventing the buildup of weeds, barnacles and more by creating a super-smooth hydrophobic surface marine life can’t latch onto.
By painting a foul release coating onto your propeller and running gear, you can expect to:
- Improve acceleration and maintenance of speed. The ultra-smooth surface creates less friction, which decreases drag and resistance, resulting in more knots.
- Decrease fuel consumption. Even the slightest buildup on your propeller and running gear causes more fuel to be used to compensate for the loss in speed and engine power.
- Reduce cavitation. An unhindered surface causes less disruption in the propulsion, and therefore causes fewer air bubbles.
- Eliminate the need for biocide and produce fewer CO2 emissions. Poisonous biocides aren’t necessary with this slippery surface, and the reduction in drag also means fewer CO2 emissions are produced.
Different Types of Topside Boat Paints
As a whole, topside paints are similar. Meant for use above the waterline, they’re durable, resistant to moisture, can endure hull expansion and contraction and resist UV rays. The differences between the types of topside boat paints are in how well they rank in each of these areas.
- Two-part polyurethane paints outperform every other topside paint when it comes to hardness, scratch and UV ray resistance and gloss and color retention. Why not stop here? Because it comes with a price tag to match. In addition to being the most expensive topside paint, it also requires very specific primer and application equipment.
- One-part polyurethane paints are perfect for do-it-yourselfers. While they don’t quite have the performance of two-part polyurethane, they’re easy to apply and provide a beautiful shiny gloss finish. They’re affordable, safer to mix and apply and easy to touch up.
- Alkyd marine enamel paints are very popular because they’re easy to apply, glossy and affordable. They require fewer coats, but will require a fresh coat each year, as they aren’t as durable. Their oil base makes them a great match for wood, and they’re easy to touch up.
It’s important to remember that regardless of which type of topside boat paint you choose, you’ll need to check compatibility with the paint that’s currently on your topside. Two-part polyurethane paints, for example, can only be painted over other two-part paints. If you’re unsure what topside paint is currently on your boat, you can do a solvent test to check or strip the entire topside before painting.
National Abrasives, Inc.
At National Abrasives, we’re here to help you prepare your boat for painting, so it looks like new. Our random-orbital finishing sanders and Mirka specialty sandpapers will get every part of your boat ultra-smooth as you prepare to paint it. Take advantage of our bulk discounts free shipping and excellent customer service to make sure you always have what you need to prepare and paint your boat for the next season. Contact us to discuss your boat preparation needs, and we’ll recommend the products that will work best for you.