On the other hand you can accept it like acne and deal with the process of popping, drying out, patching (epoxy filler and barrier coating), and repainting every couple years.
The epoxy barrier coat (and anti-fouling paint) was renewed two years ago. How often should the barrier coat be renewed? Is it time to paint again?
The epoxy barrier coat, if not mechanically compromised, should last much more than that. Antifouling paint does not last nearly that long and so needs to be recoated. Some antifouling loses its effectiveness quickly once out of the water (single season paints), and some is multi-season, but still the biocides eventually leach out or ablate away. You’ll need to lightly sand the paint to let a good surface for the fresh coat. Just be careful not to go too far through the paint and into the barrier coat.
The barrier coat needs to be renewed when it has been sanded through to the gelcoat. One trick is to use alternating colors of barrier coat. When you see an underlying color coming through the barrier coat, then it is time to patch the area or if it is extensive, then reapply the barrier coat. Barrier coats don't wear away, they get damaged by sanding off older antifouling paint.
I believe properly applied barrier coat is expected to last about 20 years. Of course, it depends upon if it gets damaged or sanded away. At least that's what I was just told as I'm about to apply Interlux barrier coat to my boat.
Is this your first time barrier coating or is this a removal and recoat ?
Can't speak to what S2 may have done, but vinylester is much less prone to blistering than polyester.
Did S2 use full vinylester throughout or only an extra layering of vinylester gel coat? Beneteau uses vinylester but only a thin gelcoat of it. Burn through that and it exposes polyester with the usual osmosis concerns. As a result they actually recommend against barrier coating on new hulls, since the prep for the barrier coat requires sanding the surface, which would compromise the vinylester layer.
Two things about that - One, if a motorboat is used frequently enough, bottom growth is not as much a problem, particularly in fresh water. Speeding through the water tends to strip much of it off. Two, having a boat out of the water for several months a year is very helpful in preventing blistering due to osmosis.
The OP is in the Caribbean where slime is not the only issue, barnacles and all kinds of other marine flora and fauna like to set up housekeeping. It will take more than an acid bath to clear the growth.
Removal only of existing bottom paints, going down to the barrier coat put on in 2000. So I can attest to a solid 21 years without problems, but now there is some small incipient osmosis cells and as I'm heading off for extended sailing I'm just redoing the barrier coat.
I don’t race the boat, it’s a com pac 19. But the growth on the bottom is mostly at the water line, much less under the water. The type of growth is seasonal with long green strands of algae, about an inch a month, in the winter, or cute little sprout-like plants, also about an inch long, in the summer. Under water it’s not green, but gray sludge, that scraps off in mats. We get a lot of sargassum here, and there’s some speculation that it scours the bottom and that the hydrogen sulfide has some effect on slowing the growth.
If you don’t paint, you’ll need to clean it more frequently. It all depends on what’s more convenient. In most areas people need to clean soft growth every 4-8 weeks even if they use antifouling paint, as the soft growth provides a foothold for the hard growth.
