Bottom Painting a Boat on a Trailer in 9 Easy Steps

Have you ever wanted to learn how to bottom paint a boat while it’s being towed? Slime, barnacles, grass, and other ugly marine animals won’t grow under your boat if you paint the bottom. It’s one of the most effective strategies to keep its integrity and performance intact.

Unfortunately, experienced sailors do not recommend bottom painting a boat while it is on a trailer since you will miss some areas.

Bottom painting a boat on a trailer is still possible, and I’ll show you a few tricks that some boaters utilize. Follow my 9-step procedure, which includes double-cleaning, removing old paint, sanding the surface, and more.

how to bottom paint a boat on a trailer

Things You Need for This Tutorial


When painting the bottom of your boat while it’s still on the trailer, you’ll need to do the following:

  • Cleaning equipment
  • Materials for surface preparation
  • Resources for the Paint application
  • The best bottom paint on the market

Boat owners who seek a more controlled release of biocides without sacrificing the antifouling capabilities of the bottom paint will love copolymer ablative paints. This paint is ideal for individuals who keep their boats in storage over the winter.

You’ll need a hard-modified epoxy paint with a high copper concentration if your watercraft stays on the water all year. This paint is also available in single-season variations.

Composite copper technology can be used by boat owners who do not want to work with high-copper-content paints. Copper content in these bottom paints can be as low as 40%.

Algae growth is always a worry when boating in freshwater. A thin-film paint is the best choice for the bottom.

Steps for Painting a Boat’s Bottom on a Trailer


Step 1. Clean your boat.

It’s preferable to get rid of any organic growth or slime while your bet is still wet. Leaving these items to dry on the watercraft’s bottom necessitates chiseling them off, which is a more time-consuming process.

That is why you should power spray the bottom of your boat as soon as you get it off the water and onto your trailer. A hand scraper can also be used to remove difficult barnacles, slime, and other things.

If you see any chipped paint, you should spray it as well.

Step 2. Strip the old paint, if necessary.

It’s never a good idea to paint a boat’s bottom without first removing the previous paint, especially if you’re using vinyl paint over a non-vinyl coat. These paints include powerful solvents that can remove non-vinyl paint coats off the surface of the boat.

If you see paint peeling, chipping, sloughing, or lifting on the bottom of your boat, inspect it. Overpainting certain areas will result in poor pigment adherence. It’s for this reason that it’s preferable to remove the old paint.

Remove the old paint from the boat’s bottom with a hook scraper. It is both safer and easier than using a chemical stripper.

If the existing paint on your boat’s bottom is in good condition, you can skip to Step 3.

Step 3. Sand the surface.

If the bottom paint of your boat is still intact and in good shape, all you have to do is smooth it out with 80-grit sandpaper and a random orbit sander. Using 80-grit disks might damage the laminate by chewing through the bottom paint. It’s also not a good idea to use a belt sander because it can flatten the hull.

It’s preferable to use a vacuum hose to collect and remove sanding dust from your sander. You could also wish to invest in a shop-vac to help with debris cleanup.

When sanding the bottom of your boat, use safety goggles and a particle respirator.

Step 4. Clean again.

To remove any sanding-related dust and debris, wash and clean your boat’s surface once more. A quick wipe with a clean towel would suffice if you are confident in your vacuum attachment.

In order for the paint to form a firm bind to the surface, a particulate-free surface is required when bottom painting a boat on trailer.

Before moving on to Step 5, make sure everything is completely dry.

Step 5. Mask off borders.

Masking tape that is used on a regular basis will tear off in less than 24 hours. That’s why a long-mask tape like the 3M 2090 ScotchBlue Painter’s Tape is necessary. Because it clings to the surface for up to 60 days and is UV-stable, I find this masking tape excellent for boat painting chores.

Check the boot stripe on your boat and begin applying the tape to a natural break in the line. To ensure a smooth border, press the masking tape to the surface every 1.5 to 2 feet.

Transducers, through-hulls, propeller shaft struts, and other metal components should all be taken off.

Step 6. Cover your trailer.

Despite the fact that you’ll be using a paint roller for this endeavor, pigment may spray into your trailer. That’s why covering your trailer with old newspapers or thick plastic sheets is a good idea.

Tape the overlapping papers together, making sure there are no gaps or holes. It will also assist to tie a rope around the sheets’ outside edges to keep them from flying away.

Step 7. Prepare the bottom paint.

The bottom paint should not be applied straight from the can. To ensure that the pigments and copper are thoroughly mixed, it is necessary to shake it first. Ideally, you should put the paint can on a paint shaker and shake it for five to ten minutes.

If you don’t have a paint shaker, you can use a mixing paddle hooked to a power drill.

Pouring half of the bottom paint into a container is an improvised method. Get a mixing paddle and stir the remaining paint in the can vigorously. Continue scraping the bottom of the can with the paddle until it can no longer scrape anything.

Slowly pour the remaining half into the paint, mixing constantly. Stop until you’ve achieved a consistent consistency and color, which should take around 15 minutes.

Step 8. Paint the surface.

Pour the paint onto a roller pan and use your foam roller to pick up some pigment. Apply the paint to the bottom of your boat in an up-and-down motion. Starting at the waterline and working your way to the keel is a good place to start.

Because this paint kind dries quickly, it’s best to work swiftly. Also, every time you refill your paint tray, remember to mix the bottom paint.

Read the paint manufacturer’s instructions to figure out how many coats you’ll need. Before applying the next layer of paint, make sure the previous coat is totally dried.

Attaching an extension handle to the roller will allow you to reach higher portions of the boat.

Step 9. Reposition your boat.

Allow for complete drying of the bottom paint before relocating your boat.

Take your watercraft into the water and back into the trailer, making sure to expose any areas that haven’t been painted yet.

Return your boat to your shed and begin working on the areas that are still unpainted, following the methods mentioned above.

West Marine has a great video on how to paint the bottom of your boat. Although the boat is not on a trailer, the procedure remains the same.


Many boat owners have no idea how to bottom paint a trailered boat. Knowing this tip provides you an advantage over others when it comes to maintaining the hull of your watercraft.

Would you be willing to share this tutorial with your social networks if you found it useful? I’m sure they’ll want to know how to bottom paint a vessel on a trailer as well. Any comments or feedback you may have will be much appreciated.

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