What paint below the waterline on a hard dinghy?

[TaylorC]

The gelcoat on my dinghy was toast, and the PO's repaint was fading and scratched, so I painted my dinghy last year with Interlux Brightside Polyurethane. This paint is for topsides only. I thought I would be putting the boat on deck occasionally, but I ended up not doing that. It turns out that three weeks in the water does not make this paint happy, it bubbled up quite a bit.

But the kicker was that over the winter with a plastic tarp over the upside down dinghy, water got through some pinholes in the tarp and was held against the paint, causing an rash of little bubbles/blisters all over bottom of the boat.

The topsides are still OK, I might be able to get away just from the waterline down with a hard antifouling/bottom paint... but I want an white or offwhite.

I'd spray gelcoat, but this is a lapstrake style dinghy and the wet sanding would take me forever.

What paint do people use below the waterline when sections of the gelcoat have been ground down and removed?

Any ideas?

[sailingdog]

Use interprotect 2000e barrier coat... the fact that it is underwater won't bother it.

[TaylorC]

I was thinking of that, it comes in white and I've used it before and it levels to a nice smooth finish. Can you use it without a covering coat?