Bottom paint on boats is designed to repel aquatic organisms, plants, and algae that can damage the hull, affect the boat’s performance, and create a continuous maintenance chore. Bottom paint is ideal for boats that stay in the water for long periods of time.
Read on to learn more about what bottom paint does, how to choose the right paint for your boat, and how to maintain your boat.
What is Antifouling Paint For Boats?
Bottom paint or antifouling paint are interchangeable terms for paint that is applied to the bottom or hull of a boat. This paint acts as a protective layer for the part of the boat that sits in the water.
Bottom paint can also be applied to the lower unit of the motor and trim units.
Most boats don’t come with bottom paint; it’s something you add aftermarket. If your boat is going to be sitting in the water for long periods of time, it may be a good idea to apply bottom paint.
What is the Purpose of Bottom Paint?
The formula of bottom paint wards off marine growth, keeping the hull cleaner and leading to less discoloration.
A layer of bottom paint also makes it easier to clean the hull of your boat, as marine growth will come off easier than it would if your boat were not painted.
Cleaning is important because a buildup of marine growth on the hull can hinder your boat’s speed and cause lower fuel efficiency and performance from your engine.
How to Choose the Right Bottom Paint For My Boat
Bottom paint is mainly recommended for those who boat in saltwater and particularly for those who plan to leave their boat sitting in the water.
Coastal areas usually see the most sunlight throughout the year, and the more sun there is, the more growth happens on the seafloor. Hulls in these areas are more susceptible to the buildup of marine growth, and the antifouling properties of bottom paint prevent the rapid growth of buildup.
Excessive marine growth on the hull can break through the gel coat of a fiberglass boat and leach into the fabric of the boat. This can cause blistering that allows water into the fiberglass and leads to delamination. If the salt water breaks through because of delamination, it will eat away at the material of the hull.
Saltwater also speeds up oxidation, which leads to discoloration of the hull.
There are different antifouling formulas depending on the material of the hull. For example, pontoons need a different type of bottom paint than wooden or fiberglass boats do.
What Are the Steps to Bottom Painting?
First, you need to determine the waterline and create a straight tapeline that makes a clean border between the bottom and the side of your boat. Previous marine growth can direct you where to make this line.
If your boat bottom has never been painted, the next step is to use 60 or 80-grit sandpaper to scuff sand the gel coat to remove any wax or debris and create a smooth surface that the paint can adhere to. You should also fill in any chips in the gel coat and sand smooth.
If your boat bottom was previously painted, light sanding is required to remove any debris and create a good adhesive surface.
Generally, one to two coats of antifouling paint provide adequate protection.
After painting, pull the tape off while the paint is fresh, and launch your boat after the paint dries overnight or soon after.
How Often Does Bottom Paint Need To Be Applied?
On average, a properly applied layer of bottom paint should last two to three years if you use your boat regularly. If your boat sits at the dock in the water year-round and you take it out for cleaning only once or twice a year, the paint will not last as long. In this case, you should re-apply the paint every year.
What Is Marine Paint?
Marine paint is a urethane paint that is specifically formulated for boats and leaves a glossy finish. It’s one option you can choose for your boat’s hull. Another option is gel coat, which is a resin-based finishing material that dries into a hard, shell-like casing.
What Is the Best Bottom Paint For Boats?
The bottom paint you should choose depends on what kind of boat you have and your boating habits. If your boat sits in the water and stays there, you need “hard” bottom paint. If you use your boat frequently and pull your boat out of the water sometimes, ablative bottom paint is a good choice.
What Is Ablative Bottom Paint?
Ablative bottom paint is self-polishing paint that wears off the surface paint as your boat moves through the water. As the paint sloughs off, it exposes fresh paint that continuously protects your boat’s hull. When you put your boat back in the water, it softens the paint, and the protection is activated.
If you don’t use your boat frequently, ablative paint is not a good option for you, because it requires your boat to be in motion to expose the fresh paint surface. On the other hand, if you have a high-performance boat and often run at high speeds, ablative paint is too soft and will wear off quickly.