GRP boat with no gelcoat?

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GRP boat with no gelcoat?

Post by realnutter » Sun Apr 10, 2016 6:01 pm

Is it possible?

My Flipper Scow appears to have no gel coat.... I've been sanding paint off the bottom... I'm pretty sure it's paint from the way it flakes off... But underneath I seem to be straight into the polyester resin, with no intervening hard shiny gelcoat layer...

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Re: GRP boat with no gelcoat?

Post by JimC » Sun Apr 10, 2016 6:48 pm

Unusual for a mass produced boat but situation normal for the more exotic craft.

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Re: GRP boat with no gelcoat?

Post by Keith66 » Sun Sep 04, 2016 9:19 pm

Gelcoat is heavy, i just built a 16ft rowing skiff & it takes 6kgs plus of gel to do one coat, add another 6kgs of flowcoat on the inside & it adds up rapidly. The upshot is gelcoat can be a significant percentage of a boats weight.
Leave it off & paint it & the boat will be quicker.

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Re: GRP boat with no gelcoat?

Post by Ed » Mon Sep 05, 2016 2:12 pm

Three possible options come to mind:

First, is that they only put on a very thin gel-coat, which didn't adhere terribly well to the laminating resin, hence it is now just falling off, much as paint would do.

Second, is that they used a clear un-pigmented gel-coat, pretty common practice in those days. When we made practice kayaks at school we only used to colour the tops, the bottoms were all just bare unpigmented gelcoat.

Third, is that as you say, they did just laminate straight onto the mould, but this would seem the least likely as it wouldn't do the mould much good and would make it that much harder to get the shell out of the mould.

Easy enough to tell though, I would of thought. If you look at the glass under the paint/gelcoat once removed and you can polish it back to something close to shiny, it must of come out the mould and it must be the second or third option. Now try to sand the glass, under the paint/gelcoat and it goes straight into the fibre, then I would think it is the third option, but if not it is the second.

But as others say, I wouldn't loose any sleep about this, I would just put on a hard epoxy primer, sand and either polish or paint.

Ed Bremner

Jollyboat J3
Firefly F2942
IC GBR314 ex S51 - 1970 Slurp
MR 638 - Please come and take it away
Phelps Scull
Bathurst Whiff - looking for someone to love it

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