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Old 19-01-2015, 04:58   #1
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Polyester vs fiberglass

Hi all.
I have a question we are use to fiber glass and I'm seeing a lot of cats for sale saying built of polyester. Is polyester more strong then fiberglass and what is made of polyester? Thank you.
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Old 19-01-2015, 05:14   #2
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Re: Polyester vs fiberglass

I believe the reference to polyester is the resin used to bind the glass, boat I feel pretty sure is still fiberglass and possibly carbon fiber still.
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Old 19-01-2015, 05:15   #3
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Re: Polyester vs fiberglass

Greetings and welcome aboard the CF, SueJoe.

There are three main types of Resins used today for use with Fibreglass: Epoxy, Vinylester, & Polyester.
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Old 19-01-2015, 05:16   #4
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Re: Polyester vs fiberglass

Fiberglass is technically just glass fibers which is the reinforcing part. When coated with a resin it is now a composite and becomes the hard plastic stuff used in boats and Corvettes and other things. The resin choices are polyester, vinylester and epoxy. Poly is the cheap stuff and very easy to work with. Over 90% of all boats use this. Epoxy is the good stuff and much stronger and only high end manufacturers use this. Vinyl is in between. Poly is not waterproof and requires an epoxy bottom coat. Vinyl is being used in many boats these days as an additional waterproofing barrier on top of the poly (which would be the outside bottom) for the hulls. You still need an epoxy bottom coat though. Many home built boats use epoxy and when properly done results in a really well made boat. All of the resins are not UV resistant and will degrade in the sun so you have to paint your boat and urethane is a popular choice for this.
A fiberglass boat may have other non-glass fibers like Kevlar or carbon but it's still called fiberglass.
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Old 19-01-2015, 06:34   #5
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Re: Polyester vs fiberglass

Hi again. I saw your other post about the L450 and Salina. The new trend is to have all or part of the boats hulls built in vinylester. All vinyl would be very good. The construction specs are vague about this for these and other boats so do your homework.
A common problem for poly boats is blisters and osmosis caused by water infiltration into the laminate. Vinyl takes this issue down to almost nil.


Edit: Your welcome.
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Old 19-01-2015, 06:37   #6
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Re: Polyester vs fiberglass

Thanks to all.
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Old 19-01-2015, 06:50   #7
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Re: Polyester vs fiberglass

And to complicate it even more there is orthophthalic-polyester and Isophthalic-polyester. By selecting different resin matrices you can change the ultimate strength of the fiberglass composite.
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Old 20-01-2015, 09:48   #8
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Re: Polyester vs fiberglass

Hello Boys and Girls,

Long while no chat had a bit head under the dunk! Believe though i will be OK.

Sand Crab, any info of a resin to stick Kevlar on the glass hull in support of high strain areas. Thanks.
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Old 20-01-2015, 10:08   #9
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Re: Polyester vs fiberglass

Kevlar and iso/orth polyesters do not play well together. Best bet is to get a hybrid kevlar/fiberglass fabric. Vinyl ester or epoxy is the way to go with any kevlar.
Sorry for the hijack, sand crab.
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