Flaking/delamination so a gelcoat peel

[DaveC]

Hello,

So I hauled out my boat because I saw that there was some antifouling paint cracking at the boot stripe when I dove on her to scrape the slime away from her waterline. I had to replace some thru-hulls and I figured I'd sand and repaint the bottom while she is hauled out. There is a large buildup of antifouling, probably 20 years worth at least.

Well, upon removing the chips it looks at thought the gelcoat underneath cracked and is flaking off. It is unusually thin gelcoat (0.5mm or so) and it appears to flake off in dime sized chunks as I run a scraper across it lightly. The laminate underneath is fine and solid from what I can tell by knocking on it with a wooden hammer, and I don't see any cracks or other suspicious things in it. I checked a few other random places around the boat and it's the same underneath the paint. The boat does have extensive crazing on the deck also so I'm not really surprised.

I decided after talking with the yard that I would have everything peeled off (including the gelcoat) from the boot-stripe down and start fresh with a sealer, barrier coat, and new antifoul. So because this is my first time at this, I have a couple of questions:

1. Is there any reason not to have the gelcoat peeled and then apply new gelcoat before the barrier and antifoul? (in consideration of the abrasion resistance gelcoat offers to grounding or such) I know it adds cost but is that the only reason not to?

2. What is the best method of buildup after a peel? I've heard using vinylester resin before or as a barrier coat is a good thing to prevent water intrusion, but I was thinking Interlux Interprotect 2000 which I used on a boat years ago with good results.

3. Would it be beneficial to add a layer of glass to replace what comes off in the peeling? I know that supposedly not much is lost but I wonder if applying a layer of vinylester or epoxy resin impregated glass would help to seal it and add a layer of gouge protectance?

Any suggestions are appreciated, especially from those who have gone through this...

Thanks and fair winds,

-Dave

[Neptune's Gear]

Are you SURE it is gelcoat that is flaking?? That would be pretty unusual - could it not be a waterproofing paint (like interprotect is)??

[DaveC]

Thanks for the reply.

I'm fairly certain.

It does seem thin for gelcoat, but directly under it is resin and laminate.

I suppose there is a chance that it was peeled previously and someone put some kind of white sealer on it that is now flaking off. The bottom paint is at least 3mm thick and of many different colors so it was done long ago if that was the case. I'll try to go to the yard and take a picture of it tomorrow.

I should state that the hull is very fair and show no signs of blistering at all. The boat is a 1979.

-David

[Neptune's Gear]

OK, that is not unusual, I suspect it has been painted on top of the resin. Perhaps has a bottom epoxy job? If so, no issue with just sanding off all the crap and going ahead with the interprotect - it can go direct on epoxy.

There are some others on here with better paint knowledge than me - you might get some more replies yet! Read the manual on the interprotect and it will give you details of what and how to go ahead.

Sanding the hull is not a nice job!

Good luck.

[DaveC]

Thanks for the replies. I'll try to make certain that it's not painted over epoxy.

Originally Posted by Neptune's Gear

Sanding the hull is not a nice job!

Been there done that... That's why I was going to have it peeled.

[minaret]

You should consider doing a search here on the forum. There are many threads on this and all your questions have been answered before.