Bottom paint type

[Bob L]

Is there a test to find out what kind of bottom paint is on a boat?

I just bought this boat from NY. The bottom is in great shape, with maybe just one layer of bottom paint. There are no areas with peeling, etc. But it is wore thin in some places. Since I'm in NC, and the boat will be in the water year round, I wanted to give it a coat before dunking it. Sorry Tim, but I don't want to make a big production out of this, no stripping, grinding, barrier coat or any of that. The paint is black in color, if that helps.

I thought I could give it a good brushing, light sanding, then a coat of paint, but I've been told the wrong paint will peel off the old. The PO is a JO, and won't return calls now that he has his money, and I doubt if he would know anyway.

Thanks,

Bob

[Tim]

Since you say the paint is worn thin in places, it would seem to be an ablative paint. One way to test this theory would be to wet an area and see if a lot of paint comes off on a brush or your hand. Harder, non-ablative coatings will leach out much less paint in this test than an ablative, which will basically rub right off if you scrub enough.

If it's ablative, just scrub the bottom with a brush and water (if necessary) before repainting; otherwise, just repaint over what's there, as long as it's more or less clean and in sound condition. If you go with another ablative paint, you should apply at least three coats if your boat will be in the water for a year or more. For seasonal use, one coat per season is just adequate. Ablative paints work by constantly rubbing away and exposing new material, so the effectiveness of the coating is directly related to the thickness of paint on the boat.

For more traditional paints (non-ablative), the thickness of the coating is not directly responsible for the effectiveness of the paint, so avoid applying multiple coats each time, as you will only build up the thickness with no overall effect on fouling resistance.

The marine catalogs usually have a compatibility chart to show which paints can be used over which. Check that out for more info.

[Bob L]

Yep, it rubs off. if you brush up against it will come off on your clothes, sort of like a chalkboard, except with black chalk.

Are all ablative paints compatable with each other?

Thanks Tim!

[Tim]

There are generally only compatibility problems between broad categories (chemical makeup) of paints, not between brands. So any ablative should be able to go over any ablative, no problem.

The chalkboard analogy sounds exactly like an ablative paint would act. It's a safe bet that's what you're dealing with.

Good luck!