Clearly, most of us are inclined to use epoxy for repair on our polyester boats, and maybe even for new pieces. Why?
No doubt this has been discussed at length over the years but maybe a definitive discussion and even a table, to be placed with the sealant table would be instructive and useful. Maybe even include the types of fiber reinforcement, too.
Epoxy, polyester, vinyl ester
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Quetzalsailor
- Master of the Arcane
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- Boat Name: Quetzal
- Boat Type: LeComte North East 38
- Location: Philadelphia, PA
Re: Epoxy, polyester, vinyl ester
For me personally, it is the secondary bonding characteristics of epoxy that make it vastly preferable to the "esters" for repair jobs. Most all repairs at some point require a mechanical bond to the boat and epoxy is far and away stronger than polyester at adhering to the repair area. There are arguments for repairing with the same type of material that the original object was made from, but frankly I haven't heard one yet that begins to overshadow the advantages of epoxy and the bond that comes with it. FWIW.
Ryan
Ryan
Re: Epoxy, polyester, vinyl ester
I use all three. Mostly Vinlyester these days.
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Quetzalsailor
- Master of the Arcane
- Posts: 1100
- Joined: Fri Aug 26, 2005 9:53 am
- Boat Name: Quetzal
- Boat Type: LeComte North East 38
- Location: Philadelphia, PA
Re: Epoxy, polyester, vinyl ester
Surely, cost is an important consideration. Particularly when large volumes are in question. (The cost of doing it twice should be taken into account, too.)
Cold bond strength is important, but enough is really enough; excessive is not necessary. Many boats are tabbed and joined with cold bonds, probably few are consciously bonded when the parts are 'green'. We're still sailing 'em.
Vinyl ester resins are not, so far as I know, readily available for amateurs. Advantage includes, I understand, workability like ordinary polyesters, only a little more expensive than polyesters, better resistance to osmosis and water intrusion.
Some of these resins are simply unsuitable for the purposes for which they are often used: I would say, contrary to lots of examples demonstrating otherwise, that polyesters are unsuitable for tabbing or bonding wood where the wood is alternately wet and dry; the wood changing size will sooner or later break the bond between wood and polyester. Epoxy does better, but not perfectly. Encapsulating wood, members or cores, with polyester is less proof than epoxy because the epoxy has lower permeability to water. Plenty of examples demonstrating adequacy of either, though. Comes down to workmanship and subsequent abuse (like not sealing holes).
Longevity is a concern, more when the structure is heavily or cyclicly loaded. Most parts of our heavy cruising boats are not susceptable to this problem, but there are areas where the better strength of epoxy is desirable (to avoid having to fix it again, or to cope with an inadequacy that shows up after only a few decades). On the lightly constructed side, there are epoxy-glass FD from the early '60s that are still raceworthy; polyester-glass FD are not raceworthy after a decade or so.
Cold bond strength is important, but enough is really enough; excessive is not necessary. Many boats are tabbed and joined with cold bonds, probably few are consciously bonded when the parts are 'green'. We're still sailing 'em.
Vinyl ester resins are not, so far as I know, readily available for amateurs. Advantage includes, I understand, workability like ordinary polyesters, only a little more expensive than polyesters, better resistance to osmosis and water intrusion.
Some of these resins are simply unsuitable for the purposes for which they are often used: I would say, contrary to lots of examples demonstrating otherwise, that polyesters are unsuitable for tabbing or bonding wood where the wood is alternately wet and dry; the wood changing size will sooner or later break the bond between wood and polyester. Epoxy does better, but not perfectly. Encapsulating wood, members or cores, with polyester is less proof than epoxy because the epoxy has lower permeability to water. Plenty of examples demonstrating adequacy of either, though. Comes down to workmanship and subsequent abuse (like not sealing holes).
Longevity is a concern, more when the structure is heavily or cyclicly loaded. Most parts of our heavy cruising boats are not susceptable to this problem, but there are areas where the better strength of epoxy is desirable (to avoid having to fix it again, or to cope with an inadequacy that shows up after only a few decades). On the lightly constructed side, there are epoxy-glass FD from the early '60s that are still raceworthy; polyester-glass FD are not raceworthy after a decade or so.