How to Bottom Paint a Boat on a Trailer

How to Bottom Paint a Boat on a Trailer? – Easiest Way Explained by Experts

Bottom paint of a boat is necessary since that will prevent marine growth. With the right paint, you can prevent aquatic plants from getting attached to the boat, so picking the suitable paint and knowing the right way of bottom painting is extremely necessary. Painting a boat is a little sweat breaking job, but it is more daunting to paint the bottom part of the boat. You need to give real effort when doing the bottom side painting.

Thankfully, we have experienced people who know exactly how to minimize the effort and get effective results. If you want to learn how to bottom paint a boat on a trailer, then you are going to love this guide.

We have designed a step by step guide of bottom painting, and it is suggested by expert boat painters who have been doing the job for very long. So without further ado, let’s get into the process!

How to Bottom Paint a Boat on a Trailer? – Step by Step Guide by Expert

For boat bottom painting, having a trailer is a must! With a trailer, the bottom painting will become easier. In the case of small boats, they can be turned upside down easily, but make sure you remove the motor first. For the medium size, the boat trailer is essential. If you don’t own one, you can rent one. However, let’s get started!

Things You Will Need

There are a bunch of things you will be needing to do the bottom paint successfully. Here are them!

  • Paint tray.
  • A Trailer.
  • Primer.
  • Suitable paint.
  • Sander.
  • Liners.
  • Paint roller. (high-quality)
  • Brush (disposable)
  • Protective suit.
  • Hand gloves.
  • Head sock.
  • Respirator.

Choose best quality bottom paint

Choosing the hi-quality bottom paint isn’t a tough job since the suitability is labeled on the paint bucket. You just have to check that. When choosing paint, you have to consider two things: the climate condition under which you will paint and another is the material of the boat. The most widely used materials for the boat are Fiber and steel.

For fiber boat painting, these paints will work well.

  • Rust-Oleum Marine Topside Paint.
  • TotalBoat Wet Edge Topside Paint.
  • TotalBoat JD Select Bottom Paint.
  • Aquaguard Water-based Anti-Fouling Bottom Paint.
  • Rust-Oleum Marine Flat Boat Bottom Antifouling Paint.
  • Interlux Fiberglass Antifouling Paint.

And for steel boat, the best would be the Hawthorne Synthetic Enamel Paint. A lot of users have used this paint on a steel boat, and the result was outstanding. That’s why experts suggest only Hawthorne Synthetic Enamel Paint for steel boat bottom paint.

However, before you finalize paint, check the manufacturer's recommendation. You will find recommendations for climate conditions, temperature, boat material.

Taking Out the Boat

You can’t do the bottom painting in water, obviously. So you have to haul up the boat. You won’t be hauling the boat with your hand, that doesn’t make any sense, you have to use a trailer hitch that is attached with a vehicle, that will take out the boat from the water. You will need someone to assist you. If there isn’t anyone, there are marinas that can be hired.

Remove fouling & Cleaning the boat.

If you haven’t applied any anti-fouling paint on the bottom of the boat, then there is a high chance that there will a lot of aquatic plant growth. And for painting it, obviously, you have to remove those fouling.

For removing that there isn’t much to think about. Pick a used cloth and wipe off all the fouling; they should come loose easily. And if the fouling has become hard, then try to remove that with a strong knife.

After you have removed all the fouling, thoroughly wash the boat bottom with water. Some people use soapy water, but that isn’t necessary.

Prep and Sand

If the bottom of the boat has old paint, then it is mandatory to remove that first. You cannot paint over old paint; the paint wouldn’t last. For cleaning out the old paint, the best way is sanding. If you have an electric sander, it will be more comfortable, but if you don’t have one, you have to do that with hand. Pick 80-grit sandpaper and keep sanding until you have removed all the oil paint.

Once the sanding is done, remove the dust layer and thoroughly wash the surface suitable for priming.

Tape the waterline

The bottom paint is applied to the boat portion that remains under the water. When you have cleaned all the fouling and removed old paint, you might not get the waterline. You can make an assumption and tape a line from where you will start painting. You don’t have to be accurate if the paint goes a little up from the waterline, that’s not an issue.

Use primer

Time to add the primer, and then you can paint. Before applying, stir the primer properly with a stick and then apply the primer on the surface. The edges should be primed with a paintbrush. The primer will take one or two hours to get dried properly. And once the primer is dry, with the 80-grit sandpaper sand properly.

Apply the paint

Like primer, before applying the paint stir that with a stick for 5-minutes. Then take the tray, fill that with paint and dip the roller in. You should start bottom painting from the edges and then keep distributing paint. Make sure you paint evenly. The area that is hard to reach, or where the roller won’t work, use a paintbrush in that case. Once you have done painting, wait for a while and let it scorched.

And the sand again for the second coating. Why should you repaint it? For a better lifespan. When you sand the paint and apply again, the paint sits extremely strong. Once the second coating is done, leave the boat for a day to get dried properly.

Consider the Weather Condition for Bottom Painting

As we mentioned above, before finalizing any paint, check the manufacturer recommendation. You cannot paint anywhere you want, there are a few things that you need to consider, and the weather condition is the most important one. Look at the paint labels; the manufacturer recommends the required temperature and humidity under which the paint should be applied.

Since there are different kinds of paints from different manufacturers, we cannot say the exact temperature or humidity. But most paint requires a temperature between 50 to 90-degree Fahrenheit. This is the ideal temperature.

And for moisture, you have to look at the manufacturer's recommendation. But one thing that you should never do is, painting in direct sunlight, that will make the paint extremely ineffective, and they will come to loose very soon.

Frequently Asked Questions

What is the Bottom Paint?

Paint that is applied at the bottom of a boat that is called bottom boat paint. This paint is done on the boat portion that remains under the water. Bottom paint isn’t similar to topside boat paints or other paints. Bottom paint comes with some anti-fouling properties which prevent all the aquatic plants to get attached to the boat bottom and grow. Topside paints don’t come with such properties because the top side of the boat doesn’t require that.

How do you prepare a boat for bottom painting?

A good anti-fouling bottom paint wouldn’t cost much. You should get your hands on a good one within 10 to 20 dollars. There are few which are expensive, if you don’t have the budget, going with the under 20 dollar paints is absolutely beautiful.

What happens if you don't bottom paint your boat?

If you don’t apply anti-fouling bottom paint, it has major drawbacks. First of all, there will be a lot of aquatic plant growth at the bottom of the boat. And then, when those aquatic plants grow bigger, they affect the speed and turns of the boat, which is a very serious thing. Lastly, if the plants grow very big, it can affect the balancing and the lifespan of the boat bottom.


This is exactly how to bottom paint a boat on a trailer! We would suggest having an assistant with you when you start preparing the boat for painting, that will be extremely helpful. When picking the paint, make sure you read all the manufacturer's recommendations because there are different paints for different boat materials.

You cannot apply a fiber boat paint on the steel boat, that wouldn’t last. Make sure you consider the weather condition as well.

So this is all! Follow the guide; you will be able to paint the bottom efficiently. If there is anything else you need to know, make sure you hit us through the comment section.

Happy painting!

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