A fresh old gelcoat reveal

[Drinky Crow]

I just payed a lot of $$$$ to have 38 yrs of antifouling paint removed by dustless blast.

Haven't seen it yet but the contractor said the bottom looked very very good no major issues just a few small wounds needing putty.

So, has anyone here applied antifoul directly over gel coat? How'd it work out? Got some Petit hard ablative and was planning to use their tie coat primer but can't locate any locally. Not using Interprotect because of time needed to dry hull before application.

 

[marcham]

You'll need/want a barrier coat first.... after doing all that work.

 

[Don S/V ILLusion]

Putty? Please tell us not really.

 

[BarryL]

Hey,

Years ago when I had my boat bottom soda blasted, I used Pettit Protect before applying bottom paint.

Pettit | Pettit Protect

It was expensive, but was easy to work with and I believe was effective.

Barry

 

[Davidasailor26]

The gelcoat is probably polyester which, by itself, is not completely waterproof and could blister eventually. Some manufacturers use a thin layer of relatively waterproof vinyl ester over the polyester, but there’s a good chance the blasting would’ve removed that if there was any. You could just go over it with primer and paint, and take your chances, but if you get blisters you’ll need to grind them all out, dry the hull, fair, barrier coat, prime and paint again. I know epoxy barrier coat for the whole hull can be expensive and building up the recommended thickness is time consuming, but it’s the best way to ensure you don’t have even more work in the future.

For any existing imperfections use an epoxy based fairing compound. Under the waterline you don’t want any kind of polyester putty that will absorb water and fail.

 

[Drinky Crow]

Ok never mind. I has Primocon.
Using the word "putty" generically. Of course I have a two part waterproof epoxy product.
You guys that barrier coated how many wks did you leave the bare hull drying out in the sun or tented off with a de-humidifier working?
Yard guy who does boat repair and has build a couple race boats (Mt. Gay 30, did keel in my avatar) warned me off barrier coating unless doing above as without will trap moisture in which creates other issues.
Boat's been in the water 38 yrs and no blisters and of course a moisture meter will show it ain't dry so I won't risk the barrier but will risk the blisters.
Interesting about the vinylester. I'll ask Clint. Boat built Rhode Isl. in '86.

 

[BarryL]

Hi,

For me personally, the soda blast guy finished. i spent about a week fairing the keel. Then I put on the barrier coat. I didn't find any blisters after the old bottom paint was removed so I wasn't worried trapped moisture. This was back in 2008.

If you want to read more about, I documented the work here

https://www.sailnet.com/threads/bottom-paint-1-me-2-all-done-test.42402/#post-302572

For some reasons the pictures are gone but i still have them if anyone is interested.

barry

 

[FastOlson]

It's routine for a yard to sand (rough up) the factory gel coat. Then solvent wash it. Then apply a couple coats of bottom paint.
Your boat - your rules, tho.

 

[rgranger]

Putty? Please tell us not really.

 

[Drinky Crow]

Putty? Please tell us not really.

I hope not. There was a blister that bled red when squeezed.


When exposed looked reddish w/maybe some epoxy neat painted over it.

The one on the right. When Dremeled out turned grey. 5200? Can't be lead too soft and beside above keel joint.
Guesses?

 

[Drinky Crow]

So I'm about to slather this stuff... https://fibertek.ca/collections/epox...ducts/quikfair ...all over a divot under the bow and low spots just aft leading edge keel stubby approx. parallel to forward keel bolt. Find diagram this page...
C&C 27 Assoc – Sea Change – The Mark V
Got a buncha' smaller voids/pits on stubby.
Any reason why I wouldn't use excess fairing compound to also fill those?
Should I coat all fairing compound applied with neat epoxy?