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  #11  
Old 05-25-2006
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Unfortunately, the different resins have some drawbacks, which don't appear to be mentioned above.

Polyester resin is the most common and cheapest, but is the most prone to blistering and osmosis problems.

Vinylester resin is a bit more expensive than polyester resin, binds well to polyester and vinylester resins, and is much more resistant to osmosis problems.

Epoxy resin is the most expensive of the three resins, and it binds well to both polyester and vinylester resins, and is quite resistant to osmosis problems. However, most epoxy resins will lose structural strength at higher temperatures, and this can be a serious problem if you want a dark colored deck or topsides. It is extremely unadvisable to haven anything other than white if you're using epoxy. Epoxy generally requires oven curing to ensure a complete and consistent cure.

Vacuum infusion is a good way to get a low resin, high strength laminate. However, vacuum infusion has to be done properly, with the right resin consistency and proper pressure for the piece being laminated. One caveat, the surface left by a vacuum infusion process is a bit more difficult to tab additional fiberglass to later on from what I have read/heard from people in the industry.

Cored hulls are generally lighter, stronger and stiffer than solid laminate hulls. A properly laminated cored hull is going to make a much stiffer and lighter boat than one with a solid laminate of equal strength. The real problem with cored hulls is what can happen if the cored hull is not properly designed where the through hulls penetrate the laminate surface.

On better boats, the area around the through hulls is either solid glass, or has had the core removed and been filled with thickened epoxy, to seal the core and prevent water penetration and migration into the laminate. Anyplace a cored laminate is breached, the core should be sealed from any possible moisture penetration, or the moisture entry can lead to delamination. This is true of both the hull and the deck.

Some boat manufacturers avoid this by either using solid laminate below the waterline, or leaving a section adjacent to the keel solid laminate. Some only core the deck, where the ight weight and high stiffness are more critical, than in the hull.
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
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her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

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  #12  
Old 05-25-2006
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Sailingdog,

Good points all. I did want to touch on one thing that you mentioned. While it is true that epoxy does lose strength with elevated temperatures, (as does polyester and vinylester but to a proportionately lesser extent), I did some research on this topic a few years ago. From what I was able to turn up, the data that I saw suggested the better grades of epoxy formulated for marine use, if properly cured (and you and I are in agreement on epoxy curing) really does not begin to lose significant amounts of strength due to high temperature until the laminate sustains prolonged exposure to temperatures in the very high 200 to mid 300 degree range for an extended period of time. While temperatures in that range can occur in the marine environment, they are not likely to occur in the marine environment, even on dark hulls. From what I was able to tell the problem of strength loss due to heat should be considered more relevant on boats that have not been properly post-cured.

If I had to pick a resin to build a composite boat today, I would probably chose vinylester resin with epoxy secondary bonds.

Respectfully,
Jeff
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  #13  
Old 05-25-2006
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This is not to say that epoxy is not a good or proper material for patching, strengthening or re-inforcing GRP boats, or making repairs to GRP boats.

Epoxy, in the relatively thin and small quantities used in most repairs will cure properly. The statement about requiring an oven for proper curing has to do with the quantities of epoxy that are used in building an entire hull as a single piece.
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

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  #14  
Old 05-26-2006
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Bernie....it sounds like you're talking about a Tartan or C&C. The builder would be a good indication to how well done the process is.
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PBzeer:

You are right on - Tartan. While I was looking around I was warned about their cored hulls. That is what brought on this discussion threat --- I've learned quite a bit. I'm still a little unsure but after I reread these the replies to this post for the umpteenth time I'm hoping it will sink in.

Any thoughts on the newer 1990+ Tartans and/or C&Cs for primarily coastal and some Carribean sailing?

Bernie
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  #16  
Old 05-26-2006
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Cored hulls aren't necessarily a bad thing. If the manufacturer has taken the care to put the thru-hulls through non-cored areas, then the hull should be fine.

One thing about cored hulls, they are more complicated to repair, compared to solid laminate ones.
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

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  #17  
Old 05-26-2006
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Though I'm no expert, if I could have bought new, I would have bought the Tartan 3400.
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Free, is the heart, that lives not, in fear.
Full, is the spirit, that thinks not, of falling.
True, is the soul, that hesitates not, to give.
Alive, is the one, that believes, in love.
JCP


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