Tag Archives: ablative bottom paint

Using a Signal Coat Indicator for Repainting Ablative Antifouling Paint

Anti-fouling paint is a type of underwater hull paint, also known as bottom paint. These specialized coatings are designed for the exterior of the hull of a ship or boat and combat the growth, as wells as, the detachment of underwater organisms, such as seaweed, algae, and barnacles. These aquatic life forms bind to the hull and impact a vessel’s performance and longevity.

Anti-fouling paints are often applied as one component of a multi-layering process which can have other benefits in addition to their antifouling properties, such as acting as a barrier against corrosion on metal hulls that will degrade and weaken the metal, or improving the flow of water past the hull of a boat or yacht.

Boaters recognized early on it is important to keep the bottom of their craft free of barnacles due to loss of speed and performance. The key is knowing when to pull your boat out of the water for a new bottom paint application. Ablative paints are typically reapplied every 1–3 years. One way to ensure you reapply your ablative antifouling paint when it’s needed is by adding a signal coat or flag coat.

To apply a signal/flag coat, when you are getting multiple coats of ablative bottom paint applied to your hull, make the first coat a different color. For example, if the bottom is going to be painted blue, make the first coat red. When the blue paint wears off and you see the red flag coat, it is time to repaint.

ablative bottom paint
Aquaguard is an excellent antifouling bottom paint

If you need further assistance with your boat painting project feel free to contact our technical team Monday-Friday 8:30-5:00 pm EST.

Do I Need Bottom Paint on My Boat?

Sea Hawk Cukote Bottom PaintTypically when people discuss bottom paint on a boat they are referring to Antifouling paint. Bottom paint prevents growth of organisms that attach to the hull and can affect a vessels speed, performance, and durability when boat is kept in the water for extended periods of time.  If you don’t have that problem, you may not need bottom paint. Antifouling bottom paint typically has a flat, dull finish that is used below the waterline.

If you don’t have a growth problem or would like a nice shine to your boat’s bottom look to our other items like gelcoat or a topside paint for moderate water exposure or an aluminum paint with no antifouling agents. Gelcoat adheres to most gelcoats or fiberglass/resins, see how to apply gelcoat.  A boat bottom with antifouling will need to have it removed via sanding, sandblasting or bottom paint remover before a different type of paint will adhere.

There are generally two types of bottom paint both of which have several variations that create a multitude of products in the market place. The two different types or categories of bottom paint include hard bottom paint and ablative bottom paint.

Hard Bottom Paint vs. Ablative Bottom Paint

Hard bottom paint is bottom paint that is a hard modified epoxy. After you apply hard bottom paint it is very durable and does not wear off. Hard bottom paints typically have a higher ratio of pesticides (usually copper) in them that are exposed in the outer surface of the bottom paint coating. As time goes by, the coating oxidizes and becomes less effective in combating marine growth. Hard bottom paint is generally used on boats when the boat sits for long periods of time without moving at all, or there is little movement of water (current/ tide) around the boat. You should not use a hard paint if you boat comes out of the water such as on a trailer or a lift. After 72 hours, the hard bottom paint will oxidize on the outer surface from the air and becomes ineffective. If you are trailering your boat, or keep it on a lift you should always use ablative bottom paint.

Ablative bottom paint, also known as self- polishing bottom paint, is softer and allows the coating to wear off at a controlled rate. Much like a bar of soap, once the boat moves in the water or there is a current and or tide, the outer layer slowly wears away. The wearing away of the self-polishing bottom paint allows for new, unoxidized paint to be exposed. Therefore, if you are trailering your boat, or it comes in and out of the water for any reason, the paint will oxidize within 72 hours. However, once placed back in service, that oxidized ablative paint wears away and exposes a new fresh outer coating with active protection. Ablative bottom paint is a newer technology then hard paint. It is the preferred bottom paint of most users since it typically lasts longer and continuously exposes a new active outer coating that protects against marine growth.

How long does bottom paint last on a boat?

In general, you should apply boat bottom paint once a year, however; some bottom paints can last for two years. If your boat is kept in the water or you use it regularly, you you have it checked annually to determine if it requires a new bottom paint coating.

For more how to use details see How to apply bottom paint to bare fiberglass or How to apply bottom paint over existing bottom paint.

How much does it cost to bottom paint a boat?

How much does it cost to bottom paint a boat?

The cost to paint the bottom of your boat depends on a number of factors including the size of your boat, the paint you choose and whether you use a primer or not. Other factors include whether you will paint your boat or hire someone to paint it. For example, Biocop TF by Sea Hawk, is a popular bottom paint and currently costs $269.77 a gallon and provides theoretical coverage of 315 square feet per gallon. If the bottom surface of your boat is 700 square feet you would theoretically need to purchase three gallons (Biocop is not offered in quarts) at a total cost of $809. 31 for the three gallons.

That may seem expensive for paint however boat bottom paint uses antifouling properties in order to protect the boats bottom from organisms found in saltwater and other elements.

For information on calculating how much paint you need to paint your boat bottom you can refer to our Bottom Paint Calculator.

What is the difference in Hard Bottom Paint and Ablative Bottom Paint?

Hard Bottom Paint Vs. Ablative Bottom Paint

Bottom paint is generally used to keep the growth off of the bottom of your boat. There are generally two types of bottom paint both of which have several variations that create a multitude of products in the market place. The two different types or categories of bottom paint include a hard bottom paint, and an ablative bottom paint.

Sharskin Hard Bottom PaintHard Bottom Paint is bottom paint that is a hard modified epoxy. After you apply a hard bottom paint it is very durable and does not wear off. Hard Bottom Paints ypically have a higher ratio of pesticides (usually copper)  in them that are exposed in the outer surface of the bottom paint coating. As time goes buy, the coating oxidizes and becomes less effective in combating marine growth. Hard bottom paint is generally used on boats when the boat sits for long periods of time without moving at all, or there is little movement of water (current/ tide) around the boat. You should not use a hard paint if you boat comes out of the water such as on a trailer, or a lift. After 72 hours, the hard bottom paint will oxidize on the outer surface from the air and becomes ineffective. If you are trailering your boat, or keep it on a lift you should always use an ablative bottom paint.

AF-33 Ablative Bottom PaintAblative bottom paint, also known as self- polishing bottom paint, is softer and allows the coating to wear off at a controlled rate. Much like a bar of soap, once the boat moves in the water or there is a current and or tide, the outer layer slowly wears away. The wearing away of the self-polishing bottom paint allows for new, un-oxidized paint to be exposed. Therefore, if you are trailering your boat, or it comes in and out of the water for any reason, the paint will oxidize within 72 hours. However, once placed back in service, that oxidized ablative paint wears away and exposes a new fresh outer coating with active protection. Ablative bottom paint is a newer technology then hard paint. It is the preferred bottom paint of most users since it typically lasts longer and continuously exposes a new active outer coating that protects against marine growth.

Related Articles and links:

Hard Bottom Paint

Ablative Bottom Paint

Applying Bottom Paint