Boat Bottom Painting
If you’re a boat owner then I’m sure you’re already aware of the importance of this subject. In this article we’re going to mainly be discussing the different types of paint and why they’re needed.
Fouling - What is it?
Fouling occurs when barnacles, zebra mussels, weeds, algae and other marine life attach themselves to the submerged area of your boat.
Some Facts About Fouling
- Once fouling starts, it spreads rapidly.
- It has been proven that fouling creates drag and reduces speed which creates extra demand on the engine and increases your fuel cost 15% – 20% or more and causes damage to the hull.
- Boats kept in cold water will not foul as quickly as boats kept in warm water or water in a highly industrialized area.
Antifouling Paint – Why Is It Important?
Antifouling paint will keep barnacles, slime and weeds from attaching to your boat. There are different types of antifouling paint: Self-polishing copolymers, controlled solubility copolymers, ablative antifouling and hard antifouling.
Types of Paint
Copolymer and Ablative are partially soluble. As the water steadily removes the paint fresh biocide is continually on the surface. Because these types of antifouling paints wear away, there is no buildup and preparation for new paint is minimal. These types of paint are good for boats that are used regularly. Repainting would need to be done every one to three years depending on the original application (thickness) and use of the boat. Generally, light sanding is all that is needed prior to repainting.
Copolymer paints allow for hauling and re-launching without repainting but ablative paints do not retain their antifouling ability for more than 30 days after being hauled out of the water.
Hard antifouling paints, such as Teflon paints, are a good choice for fresh water since there is less fouling and for fast powerboats and racing sailboats. If your boat is kept stationary for considerable amounts of time and you have the bottom of your boat cleaned regularly, this would also be a good option for you. Hard paint needs to be repainted yearly. Preparation for a new coat involves heavy sanding to improve adhesion and prevent build-up.
Teflon paints have formulas for both fresh and salt water. Whatever type of paint that you have on your boat must be completely removed prior to applying the Teflon paint.
Epoxy-based paints are excellent for marine application. Instead of replacing the gelcoat on a fading fiberglass boat hull, opt for epoxy boat paint which is harder and more durable than traditional paint. Before applying epoxy, however, the hull must be prepped first with a solvent based/thinned epoxy sealer to prevent osmosis (this is where small cracks and holes pull water into the hull). Applying waterproof clear coat or marine spar varnish over the epoxy paint will help to prevent the paint from yellowing over time.
To maintain a uniform coat and prevent your paint from chipping and blistering you need to have a barrier coat applied before applying antifouling paint. The hull should have a chance to completely dry out, then the wax needs to be removed from the bottom of your boat with solvent and the surface needs to be sanded and possibly stripped depending on the type of paint so that the barrier coat can adhere. Another advantage of the barrier coat is that it prevents water absorption which keeps your boat lighter.