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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.
 

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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 don't believe that for a second. The company still has serious legal, financial and technical issues from everything I've read.
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.
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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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.
 

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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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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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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? :confused:

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. :laugher

Ron
 

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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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Also, Epoxy is not UV resistant. I used to build strip canoes and they were covered in glass fabric and epoxy. I used West's 207 hardener with UV blockers in it, but they still want you to use UV protected varnish. On the smaller scale of boats, many builders use epoxy to create plywood wonders of all types. leak proof and amazingly strong. Some things now done with the amazing stuff allows for amazing things to be done with wood, stone, even steel! Polyester resin doesn't bond with wood very well like epoxy, which makes me wonder how well it ever worked on balsa cores.
 

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Boatpoker...does your "YES" mean you are seeing blisters on vinylester hulls from the last 10 years now? If so, do you recommend that even new boats get an epoxy barrier coat despite the anti-blister hull warranties?
 

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What an excellent question as I have an 05 Capri with a blister warranty until 10. I was planning to lightly sand the factory barrier coat to add an epoxy barrier coat followed by epoxy antifouling paint (want to try the zinc stuff to be less toxic to the environment).

Gven the existing factory antiblister/barrier coat, should I just lightly sand and go straight to the paint? And what about the zinc paint, anybody tried it?
Thanks,
Glen
 

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I just went on zanhiser's site (one of the BEST places around if you need blisters repaired) and here's what they say about vinylester:

"http://www.zahnisers.com/repair/blister/blister1.htm
Vinylester: A modified epoxy resin in a ester linking system. High physical properties and outstanding corrosion resis-tance. To our knowledge, there has never been a blister in a boat built with vinylester resin."

I would imagine boatpoker is referring to boats still built in polyester resin.
True poker?
 

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Boatpoker...does your "YES" mean you are seeing blisters on vinylester hulls from the last 10 years now? If so, do you recommend that even new boats get an epoxy barrier coat despite the anti-blister hull warranties?
My "yes" was in answer to Gramp 34's question "is blistering still a problem on recent boats". He did not specify vinylester or epoxy.
I am a bit of a skeptic and don't always believe the sales brochures. I have seen a few blisters on boats purported to use vinylester gelcoats but none on epoxy boats. I believe paying a premium for vinylester or epoxy outer coats is worth the money however epoxy bottom jobs after blisters appear is of dubious value unless you sell the boat immediately after.

I have seen hundreds of blisters in epoxy bottom jobs on older boats and would guess that 60-70% of these jobs fail within 3-5yrs. Many of these failures I am sure can be attributed to residual moisture in the hull. I once did an epoxy bottom job on my own boat ... peeled in in September, put in a heated shop with infrared lamps on it until the following April, washed with fresh water periodically and then applied 8 coats of epoxy. Blisters back in three years !

Once moisture is in the laminate (polyester resin can aborb no more than 3% moisture, glass fibers absorb no measureable amount although glass is hygroscopic to a very minimal degree) I don't believe you can ever get it out and epoxy bottom jobs are a delaying tactic only and not a cure.
 

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Boatpoker's comments are consistent with much of what I've read. Steve D'Antonio (at Zimmerman Marine) has written extensively about the need to fully peel any laminate into which moisture has penetrated before rebuilding the laminate and applying the epoxy barrier coat (he makes a persuasive case that it is not possible to dry a laminate with the application of heat.)

But I think we're getting off on a tangent and now are talking about remedial epoxy "bottom jobs" intended to correct or prevent blistering, rather than the o.p.'s question about epoxy construction.

I don't think Boatpoker would apply his concerns about epoxy bottom jobs to epoxy construction. Yes?
 

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Original epoxy construction is the way to go in my opinion as I have never seen these blister. Aeration is definetly one of many factors in blister development in polyester hulls but when you consider that most "hand laid" hulls are laminated by itinerant labour at $7.00/hr. what else would you expect
 

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There are a couple quick thoughts that I would like to add to this discussion. First of all, we tend to talk about Epoxy, Vinylester and Polyester like each of these are a single material when in fact they are all families of materials formulated for specific purposes. The properties of these materials can vary widely with the formulation.

Gramp34's discussion hits most of the important nails on the head. A few points that I would add to the overall discussion:

-An epoxy/kevlar matrix has tremendous advantage from an abrasion resistance standpoint, but Epoxy/Kevlar is more difficult to layup as the kevlar tries to 'float' out of the resin.

-There are vinylester resins manufacturerd for the crash helmet industry which when combined with Kevlar have the highest impact resistance per pound of any boat building material.

-There are major gains in impact resistance and fatique resistance per pound that can occur by eliminating (or minimizing) non-directional materials but again, like kevlar lay-up, this requires specialized lay-up techniques.

-There is a slight reduction in impact resistance over the vinylester/kevlar laminate using this same vinylester resin from the crash-helmet industry combined with axial fiberglass lamaninates, which yield and excellent ballance between cost and impact resistance when combined with the elimination of the non-directional materials mentioned from above. There can be an increase for minimal extra cost including some strategically placed kevlar in the matrix.

-vinylester itself is one of the most blister resistant materials that are out there, even more water impervious than epoxy but there can be adherence and blistering between the gelcoat and the vinylester.

-Epoxy has far superior 'peel strength' over vinylester making it a better choice for secondary bonds such as glassing in components or making repairs.

-Near as I have been able to research, blisters come in a wide variety that result from variations in source of the problem, be it the resin formulation used or issues with the lay-up method.

One of the problems with blister repairs is that the source of moisture causing the blistering may actually be coming from bilge water rather than external moisture sources. This is often the case on Asian vessels where the lay-up is often cruder relying more heavily on heaviest weight roving and larger percentages of non-directional fabrics, and may also not be as wet out, providing passages for moisture.

-Simply peeling the outer plys and applying multiple barrier coats of epoxy or vinylester will almost never permenantly repair serious blisters. The closest thing to a permanent repair is to have the boat peeled and dried out. Barrier coat the bilges, and then build up cloth and epoxy resin on the bottom. Having helped to do one of these it is a miserable job in that trying to ground hardened epoxy is a real bear.

-A slightly dated but excellent discussion of the Fundamentals of Fiberglass can be found at:
The Fundamentals of Fiberglass - Fibre Glast Developments

And that's about it, lunch time is over.....

Jeff
 
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