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Let me jump in here and add a few words to what's been said.
We're talking about hulls made from composite material. That just means there are two components in the material, the reinforcement fiber (glass, aramid/Kevlar or carbon fiber) and a resin (polyester, vinylester or epoxy).
The standard is glass fiber with polyester resin. It's the lowest cost and provides one level of strength. Kevlar has similar strength to glass, but is just over half the weight and provides more stiffness (less flexible parts). Carbon fiber can be stronger (depending on specific grade), but is dramatically stiffer than glass fiber.
Epoxy resin is a little stronger than polyester (about 15%), but its big benefit is it is far less brittle. In a polyester/glass composite, the resin starts cracking long before the glass breaks. The cracked resin no longer supports the glass fibers, then the fibers start breaking. If you see fatigued fiberglass turning white, this is what's happening. Epoxy, being much less brittle, can flex more without damage, so the glass fibers reach their full load and break before the epoxy.
So, epoxy/glass composites can tolerate higher loads and more fatigue than polyester/glass.
That would mean a boat built with epoxy resin would be stronger than one built with polyester resin, but only if the builder puts in the same amount of reinforcing fiber. Boats are designed for a certain level of strength and stiffness. By using the expensive epoxy resin the builder can achieve that strength and stiffness with less reinforcement, which saves weight for the owner, but much more importantly, saves money for the builder.
I see the benefit of epoxy as being a slightly lighter boat. On the Hanse 430 this looks like about 4% (22,958 lb vs. 24,031 lb). It'll also never blister, but has blistering of recent boats been much of a problem?
Tim
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