Repair & maintenance: Epoxy or polyester?

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Epoxy or polyester?

Printed From: Yachts and Yachting Online
Category: General
Forum Name: Repair & maintenance
Forum Discription: Questions & tips on the subject
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=6597
Printed Date: 15 May 25 at 12:42pm
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Topic: Epoxy or polyester?

Posted By: Guest
Subject: Epoxy or polyester?
Date Posted: 01 Apr 10 at 4:03pm

I have acquired a very old & knackered tasar (638) which I guess is 30 years old.

It has a number of splits where the hull meets the deck.

I am guessing it was built with a polyester resing; and I fix these with epoxy or should I buy "matching" resin?

Replies:

Posted By: alstorer
Date Posted: 01 Apr 10 at 4:30pm

if the surfaces are well prepared, epoxy will bond well to nigh on anything.

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Al

Posted By: Jack Sparrow
Date Posted: 01 Apr 10 at 5:07pm

As long as the polyester isn't fresh, your fine, I believe. I always thought
polyester over epoxy is a bit dodgy but the LINK seems to suggest
otherwise, well at least with regard to gel coat.

http://www.boatbuilding.net/article.pl?sid=06/02/14/142213

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Posted By: Guest
Date Posted: 01 Apr 10 at 5:24pm

Thanks chaps ... I have some epoxey in the garage so I will use that.

I've sort of got it in my head that this boat can only be fixed with stuff kicking around in the garage ... apart from some specalist parts which I will have to buy.

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Posted By: Lukepiewalker
Date Posted: 01 Apr 10 at 5:56pm

I believe the issue is not one of incompatibility as such, more that the different flex characteristics mean the epoxy will tend to be more rigid and 'pop' off when the underlying poly flexes.

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Ex-Finn GBR533 "Pie Hard"
Ex-National 12 3253 "Seawitch"
Ex-National 12 2961 "Curved Air"
Ex-Mirror 59096 "Voodoo Chile"

Posted By: I luv Wight
Date Posted: 01 Apr 10 at 8:17pm

The other way round - epoxy is more flexible than polyester ( especially polyester gel-coat which is very rigid and brittle).
Epoxy sticks better too, but it doesn't colour match.

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Freedom 21 Codling

Posted By: Lukepiewalker
Date Posted: 01 Apr 10 at 8:39pm

I take it back... what Guru Andy said...

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Ex-Finn GBR533 "Pie Hard"
Ex-National 12 3253 "Seawitch"
Ex-National 12 2961 "Curved Air"
Ex-Mirror 59096 "Voodoo Chile"

Posted By: alstorer
Date Posted: 01 Apr 10 at 8:46pm

careful now with your generalisations- I could mix you an epoxy that was as brittle as anything- but I could also make a pure epoxy bouncy ball. They're a remarkably broad range of materials

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-_
Al

Posted By: Rupert
Date Posted: 09 Apr 10 at 12:20pm

I've used both for Laser gunwales at various times, and both worked.

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