Painting over bottom paint

Sep 29, 2007
22
-Gemini 3400 #379 -Gemini Palm Beach, Florida
Hi, I've owned (or adopted) my 20+ year old Gemini for about 5 years and bottom painted her 3 times so far - getting ready for the 4th time less than ten months after previous paint.

I used a very high end ablative with bioside, two coats with 3 at the waterline as I always do. Moored in a lagoon off Lake Worth Lagoon in South Florida - the testing lab for trouble with bottom paints.

The paint failed immediately - growing lab experiments on the sides and ablating off the leading and trailing edges of the hull within weeks to months. Worse, at the waterline where there were 3 coats, the paint pulled off up to 10 layers of old bottom paint down to the gel coat.

I have no idea what the original zillion coats of paint were, but when I adopted her, I applied one red (flash) coat of ablative paint (slightly lower end from same manufacturer) and two coats of normal blue over a well sanded bottom. Worked fine for nearly 5 years - repainted each time lots of red showed.

Now the manufacturer tells me I must sand down to the gel coat, remove all bottom paint, and paint with a their "low quality" ablative that has moderate copper. Huh? Apparently, the high end paint's chemistry damaged all the other paint's ability to adhere.

What should I really do.
 
Last edited:
Jun 8, 2004
10,536
-na -NA Anywhere USA
Painting bottoms for nearly 45 years personally and as a sailboat dealer. Usually after three bottom paints, I always suggested removing the paint and start anew. In addition, most folks think you can intermix manufacturers paint with another. Not true. If you are not sure, a test sample near the water line is in order. Then there are some paints that can go over anything.

I think you were given good advice about the removal. Since I am not there to see physically what is happening, there is not much more than I can say.
 
Dec 1, 1999
2,391
Hunter 28.5 Chesapeake Bay
Do you really want 10+layers of bottom paint on your boat? Get rid of the old stuff, prep the bottom correctly, and put an end to your adherence problems.... Your boat will love you for it.
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Strip it. As Dave says compatability is tough to manage.

 
Feb 26, 2011
1,440
Achilles SD-130 Alameda, CA
What- is it a state secret what you're using? Some reason you can't give a product name?

BTW- when all else fails, follow the manufacturer's instructions.