Epoxy, is it the greatest or what?! - SailNet Community
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post #1 of 29 Old 02-02-2009 Thread Starter
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Epoxy, is it the greatest or what?!

Hi all,

I have been going through some reading and seeing the pros and cons of various types. For instance, a balsa core rarely seems better (in my reading so far) to a foam one.

So I am going through the boat porn (Cruising World). Hanse mentions it has 37/43/47/54/63 footers available. Interestingly it highlights that the 37 and 43 have epoxy options. Elsewhere, I have read that epoxy is 'better' but haven't seen the exact reasons versus a typical boat from a more mass market builder.

So, you are buying a new boat, what is epoxy worth to you vs the base boat? Would a 49 foot non epoxy at 650k make you want to step up to a 750k epoxy version in the same size (or switch from one builder to the next from the non to epoxy version). For instance, I have seen a more mass market maker in the above scenario on the low side vs a more custom route at the higher end (both very similar in general design; biggest difference is epoxy vs fiberglass).

Thoughts?

Regards.
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post #2 of 29 Old 02-02-2009
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Epoxy is a bit lighter and stronger than plain ol fiberglass. So you have a lighter stronger boat, hence faster if the design is the same etc. So dependng upon the cost difference, it can be worth it depending upon how you sail etc.

To me, it is worth it. I've had a step dad that was an engineer at Boeing in the 60's thru the late 80's, and he was always exorting the positives of epoxy! I would pay a premium to a point for an epoxy boat. Altho, for my needs, probably no more than 10-15% at best.

Now hopefully this thread will not turn into a Novis bashing thread, as they did have some issues in the last 2 yrs with some of there epoxy built boats, but "MOST" boats built of epoxy have been well built boats!

marty

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I drives me dinghy!
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post #3 of 29 Old 02-02-2009
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Tartan/C&C are building outstanding quality boats. The issues have been adressed and corrected.
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post #4 of 29 Old 02-02-2009
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I don't believe that for a second. The company still has serious legal, financial and technical issues from everything I've read.
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Tartan/C&C are building outstanding quality boats. The issues have been adressed and corrected.

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Actually, for many things, a balsa core is much better than foam. Balsa has better adhesion, tensile and compressive strength than most of the foams used as core materials. Its main drawback is that if the core's integrity is violated, usually by improper installation of hardware, the balsa core can get wet and rot--leading to delamination. Also, balsa does not allow large areas to delaminate as easily as foam core materials do, since water can wick along the boundary between the foam and the laminate skins, since it can have poor skin adhesion problems, especially with polyester/vinylester resin-based laminates. This is because the foam core materials do not wet out and absorb the resins as well as end-grain balsa does.

As for epoxy based laminates--yes, they're often worth it and often used in cutting edge racing boats, due to epoxy's greater tensile strength. However, epoxy does have some drawbacks, when compared to polyester/vinylester resins.

The biggest one is that most epoxy resins are prone to thermal deformation at much lower temperatures than are polyester/vinlyester resins. This is one reason most of the high-end epoxy resin boats are white in color. If painted dark colors, they can heat up to the point where the epoxy resin can soften and start to deform.

Epoxy resins are often used in repairs for another reason. Epoxy resins have much stronger secondary--adhesive--bonding characteristics than do polyester/vinylester resins. This means that the repairs made with epoxy resin are often far stronger than similar repairs made with polyester/vinylester resins.
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Hi all,

I have been going through some reading and seeing the pros and cons of various types. For instance, a balsa core rarely seems better (in my reading so far) to a foam one.

So I am going through the boat porn (Cruising World). Hanse mentions it has 37/43/47/54/63 footers available. Interestingly it highlights that the 37 and 43 have epoxy options. Elsewhere, I have read that epoxy is 'better' but haven't seen the exact reasons versus a typical boat from a more mass market builder.

So, you are buying a new boat, what is epoxy worth to you vs the base boat? Would a 49 foot non epoxy at 650k make you want to step up to a 750k epoxy version in the same size (or switch from one builder to the next from the non to epoxy version). For instance, I have seen a more mass market maker in the above scenario on the low side vs a more custom route at the higher end (both very similar in general design; biggest difference is epoxy vs fiberglass).

Thoughts?

Regards.

Sailingdog

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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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post #6 of 29 Old 02-02-2009
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just because the layup incorporates epoxy doesn't necessarily dictate quality. Just ask any Farr or Mumm owner made by Carroll Marine and sit back entertained by all the stories of epoxy problems like decks peeling off and topsides blistering as a result of incompatibility with many resins and gelcoat more so than curing time or temperature deformation.

As with most things, it's not as simple as it appears. Some mfgs have the competence to use it and others don't.

Last edited by k1vsk; 02-02-2009 at 02:13 PM.
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post #7 of 29 Old 02-02-2009
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The single biggest factor in favour of epoxy is that it is much much less likely to blister than polyester resin.

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post #8 of 29 Old 02-02-2009
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Just to set the record straight. AFAIK, epoxy OR polyester are used as binding agents together with fibreglass to build a boat. There is no such thing as epoxy vs. fiberglass. Epoxy boats are fiberglass too, but the epoxy is substituted for polyester resin as the binding agent.

Unless of course you are talking carbon fibre or other composites vs. fiberglass, but I doubt it.

Eric

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post #9 of 29 Old 02-02-2009
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Divinycell

I did not realize it when I bought the boat ( I bought it primarily on purpose, condition and cost ), but later found out it is cored with Divinycell. I know Giu would be happy to hear ( I read his thread on construction of his magnificent speedster), but what is the general consensus on this as a construction material back in 1990 when this boat was built?

I have not had reason to access the hull, but I have replaced the solar vent fans in the cabin top and it looks like this is also cored, I assume with the same material. Looks to be 3/4 inch thick with a sandwich construction. All I can say is that it was hard as H*** trying to modify the openings even the slightest.



Alright, I don't really expect a consensus, but maybe at least a few relevant (and a few irreverent) comments.

Ron
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post #10 of 29 Old 02-02-2009
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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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