Bottom Painting - FAQ
- Why bottom Paint?
Antifouling paint discourages the growth of algae, barnacles, mussels and other marine life on the underwater portion of your boat. If you boat is wooden, it prevents marine borers.
There is no acceptable antifouling agent that will stop growth altogether. If your boat remains in the water year-round, you'll have to prep the bottom and recoat it with antifouling paint at least every couple of years.
- What type of Antifouling Paint should I use?
Three of the most commonly used types of antifouling paints:
An ablative paint gradually and constantly wears away to reveal a new surface of biocide. It wears from the scouring action of water on the hull. Its advantages are:
- As long as the paint remains, it's usually effective.
- It retains its biocidal properties when the boat is left out of the water.
- It reduces excessive paint build up. However, most ablative paints need a minimum of two coats for a reasonable service life.
- Modified epoxy
With modified epoxy antifouling paint, it's the copper that wears away, not the paint. Copper particles in the epoxy gradually dissolve and allow the water to penetrate deeper until all the copper biocide is used. You can scrub modified epoxy to reinvigorate it. However, if you leave it out of the water, it will lose it potency.
One benefit of this type of paint is that one coat at each haulout will usually suffice. However the drawback to a hard paint is that over time and many bottom paint jobs, the paint film builds up and most occasionally must be removed - an expensive and messy job. Modified epoxy antifouling is a good choice for boats left in the water year-round.
Similar in action to modified epoxy, vinyl antifouling paint creates a very hard smooth finish that you can burnish. This is a good option if you race your boat. Like epoxy, it is non-ablative.
Vinyl paints cannot be applied over other types of antifouling paints.
- My boat has never had antifouling paint, but now I'd like to keep my boat in the water, what is the process for making this change?
The first time that a boat is painted, it requires some additional preparation steps. First, we would like for the boat to sit in the water a couple of days to develop a water "scum" line. Once we start to layout the new waterline, we allow for 2" - 4" of extra waterline area above the scum line. This will accommodate for future additions of equipment & gear to the boat. The first step after the waterline is laid out, would be the de-waxing of the entire underwater body. The hull is then sanded for proper adhesion and the first coat of an epoxy barrier coat is applied. Usually on the next day, the second coat of epoxy barrier coat is applied and within approximately a two hour window, the first coat of antifouling paint is applied. Applying the first coat of AF in this window will create a chemical bond which improves the antifouling adhesion. The second coat of antifouling is then applied on the following day.