For under the waterline, I recommend using gelcoat
If you wish to use paint, use a two part epoxy
Before applying either, you will need to remove all traces of anti-fouling
, typically by sanding
Additionally, you should let the hull
dry as long as possible before coating (6 months is not too long).
1. Seal any raw fibreglass (sanded with fibres showing) with a coat of polyester resin.
2. Spray at least 2 coats of gelcoat.
3. Sand with progressively finer sandpaper (300, 600, 1200) and then wax.
4. If osmosis
protection is required, skip wax in step 3, and apply 4 coats of barrier coat (like Interlux
1. Apply a two part epoxy
to any raw fibreglass (like Interlux
Epiglass), to seal the fibres.
2. Apply 1 coat of primer (like Interlux Interprotect E2000).
3. If more osmosis
protection is required/desired, apply 4 or more coats of barrier paint (like E2000).
4. Apply at least 2 coats of 2 part epoxy paint (like Interlux Perfection).