A thorough power-washing should remove all slime and barnacles
- leaving only the barnacle glue rings. Don't use too aggressive a tip on the power washer.
If you're going to paint
anyway, you can remove the rings fairly easily with a putty knife, as long as they're on a reasonably flat surface. There may be a better way, but that's what I did.
When I bottom-painted my 8 year old hull
, I power-washed, used a putty knife here and there, and then hand scrubbed w/ boat soap. After that, I used a solvent to be sure there was no wax remaining on the fiberglass
I masked the waterline with blue painters tape. Then a sandless primer (2-3 coats), and then Pettit Hydrocoat water-based bottom paint
(2-3 coats). Carefully followed directions as to timing between coats.