Bottom Paint Source

[Ironfish]

Originally Posted by NoBozo

The old paint HAS to come off.

Not necessarily. The new paint has to be the same as (or compatible with) the old paint, and the old paint has to be structurally intact. I have an ocean boat that stays in the water year round (south winters and north summers). Four years ago, it was stripped to the gel coat, Interlux barrier coated (prevents water intrusion into the fiberglass, aka blisters), and painted with 4 coats of Micron brand antifouling bottom paint.

Every year since, it has been hauled, cleaned, scuff sanded, and painted with a single coat of Micron bottom paint, right over the old paint. I probably won't have to strip it to the gelcoat for another 10 years.

If the bottom paint isn't peeling off, a marina can have a sample of the paint tested, and a new coat of the same (or similar/compatible) paint can be applied over the old paint. It's done all the time, and for that matter, most of the time.

Most bottom paints contain copper. Recently, low/no copper paints have been introduced, that are apparently more eco friendly. Some people claim that the copper free paints do not do as good a job at inhibiting growth, but that is probably a non issue for seasonal lake use. However, finding a copper free bottom paint that is compatible with older paint may be a challenge.