Hard paints are best for boats that are in the water for long periods since these paints will oxidize out of the water. Ablative paints "self clean" and wear away slowly as the boat moves through the water and will not lose effectiveness outside of the water making them a great choice for trailered boats.
Bottom paints are usually one of two types: hard or ablative, with variations whose effectiveness depends on how much time the boat spends in the water, and how often it moves. Hard bottom paints are typically less expensive than ablative antifouling paints.
Many of us in the Great Lakes (cold freshwater) use a thin, slick, low-friction copper based product like Interlux VC17m, Pettit SR-21, or West Marine FW-21. It's easy to apply and doesn't require a ton of prep or sanding.
How often you use your boat can impact the lifespan of the antifouling used. Antifoul on boats used regularly will last around 10-12 months, however, if your boat isn't used for extended periods and is sat on a mooring this will reduce to around 8-10 months before the hull becomes excessively fouled.
Although effective at preventing bioaccumulation, these paints – made from compounds such as copper, arsenic, and other biocides – eventually flake off or leach out into the water releasing harmful chemicals into the marine environment.
If you plan to store your boat in any aquatic environment, you will need to apply antifouling paint. By leaving your boat in the water with no protection, you are letting marine life grow and attach to your boat, increasing your boat's fuel consumption and slowing the boat down on the water.
Do you need to apply a primer before using antifoul? If you are starting from scratch with a bare hull or you're applying on top of an unknown antifoul, you will likely need to apply a primer before using antifoul.
Complete a high pressure fresh water wash to remove loose antifouling. Ensure all residue and wash water is contained and disposed of according to local legislation.
Typically, 2-3 coats are required for one season of use. However, if your existing antifouling is in good condition, a touch-up may be suffice. Also, some antifoulings, including Seajet Coastal 037 Antifoul and Hempel Tiger Xtra Antifoul only require one coat for a whole season.
Boats that stay in the water the entire season will need to be painted more frequently than a boat that is trailered or lift kept. A general rule is to paint the bottom once a year, however, boats that do not spend a lot of time in the water when not is use may be able to stretch the paint out for up to two years.
Modern antifouling paints
In modern times, antifouling paints are formulated with cuprous oxide (or other copper compounds) and/or other biocides—special chemicals which impede growth of barnacles, algae, and marine organisms. Historically, copper paints were red, leading to ship bottoms still being painted red today.
When choosing a bottom paint, it's essential to consider factors such as the boat's usage patterns, the type of water the boat will be used in, and environmental regulations governing antifouling agents. It's also important to choose a paint that is compatible with your boat's existing paint and surface preparation.
There are several on the market designed specifically to paint a boat deck. They have some sort of grit or tiny rubberized pellets mixed in with the paint, to give the boat's deck a fresh look but still maintain its non-slip properties.
How do I prepare the boat for bottom painting? Preparation involves thoroughly cleaning the boat's hull, sanding the existing paint (if any), and making sure the surface is smooth. It's important to remove any dirt, algae, or old paint to ensure proper adhesion of the new layer of antifouling paint.
If the bottom of your boat is well-covered by a layer of gel coat, you'll need to de-wax it before sanding. Otherwise, if you're just painting over an existing coat or repainting boats, you can go straight to sanding or power washing away loose paint.
Boaties use it to keep the nasties away – slime, weed, barnacles and other creatures that love to grow under your boat and slow it down or eat it away. The way it works is by using a biocide, which means 'life-destroying'.
The process of bottom painting can be messy and costly to do every year. It requires sanding down the boat's bottom and repainting with new antifouling paint to continue protection. But luckily if you use multi-season paint you can get away with a touch up for a year or two.
Full cure is achieved at 72 hours.
Here's how antifouling benefits your boat: Prevents Marine Growth: The biocides in antifouling paint actively repel marine organisms, stopping them from forming colonies on the hull. Without this layer of protection, marine growth can quickly accumulate, causing drag and slowing your boat down.
Durable, strong, and resistant to abrasions, steel is one of the most popular boat construction materials, especially in the realm of large sea-traveling vessels. Due to its strength, boats crafted from steel can often safely undergo professional pressure washing without suffering damage.
If your existing antifouling is in poor condition, we strongly recommend removing it completely before repainting.
International's antifoulings are formulated to the optimum viscosity, or thickness, for their designed application thickness. Thinning can significantly affect the application properties of an antifouling. You can use our Paint Estimator to determine how much paint is required.
WHAT ARE THE TYPES OF ANTIFOULING PAINT? There are 2 basic types of anti-fouling paints – hard and soft. Those that allow the release of the toxins through the paint film, and those that shed part of the paint binder/toxins in layers through friction. The latter are referred to as “soft” or “erodible” coatings.
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.