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Old 12-06-2011, 03:54   #1
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Why a Composite Cat ?

I'm likely going to be in the market for a cat in about a year or so, and I've started looking online at what's available. I know the plus/minuses of fiberglass and aluminum but what are these "composite" cats? Should I consider one? Why or why not? Advantages and disadvantages? Maybe a pretty basis question I know, but actually I don't know ...
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Old 12-06-2011, 04:12   #2
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Re: Why a composite cat?

Composite means made from more than one material. Most composite boats will be made from marine plywood that is then covered in GRP and / or epoxy. The good points are that this makes then extremely strong without being heavy, both important properties in a cat.

However, if there has been ANY damage over the past few years, theres a good chance that water can get into the ply/grp sandwich, resulting in the wood sweeling up and splitting/delaminating.

My personal advise would be, get a FULL out of water survey done. If that comes up 100% then great, if ANY defects or poor repairs are found, run away!
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Old 12-06-2011, 05:06   #3
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Re: Why a composite cat?

You say they are "extremely strong". Would they be less likely to incur damage from a grounding or hitting something in the water than a glass boat? I guess what I'm asking is are they stronger than fiberglass?
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Old 12-06-2011, 05:30   #4
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Re: Why a composite cat?

Wood/epoxy whether strip planked, cold molded, double diagonal or simply plywood and glass are all considered "composite" construction. There are big variables in weight and strength to each method but each method less expensive to produce a "one off" design as you do not need to build a mold as in a 'glass boat (there are construction methods which allow for 'glass construction w/o a full mold but they are less common).
IMO cold molding and strip planking produce the highest strength to weight ratio of composite construction, followed by double diagonal and finally plywood. Generally puncture resistance is better than a cored 'glass (very thin outer skin) and about the same as a solid glass. None of the light weight construction methods is very good when it comes to serious groundings like being beached in surf or hitting a reef at high speed.
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Old 12-06-2011, 06:41   #5
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Re: Why a composite cat?

Fiberglass is "composite", glass in a polymer resin. I think you're going to need to be a lot more specific.
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Old 12-06-2011, 07:07   #6
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Quote:
Originally Posted by thinwater
Fiberglass is "composite", glass in a polymer resin. I think you're going to need to be a lot more specific.
When I look at a boat listing, say on YachtWorld, they list the hull as FG for fiberglass and C for composite. It's the composite other than fiberglass I'm interested in.
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Old 12-06-2011, 07:49   #7
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Re: Why a composite cat?

In the context of Yachtworld listings "composite" could also include carbon fibre and other exotic materials in addition to wood/glass composite construction particularly if looking at high tech race boats and high end multihulls.
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Old 12-06-2011, 07:55   #8
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Re: Why a composite cat?

"Composite" would include many hull types of more than one material. Wood or foam "strip plank" with structural glass inside and out, are one example, as is conventional "foam core" vacuumed in a mold, or WESTed ply with epoxy both sides and FRP components. Even "cold molded" wood, may or may not be considered "composite", depending on weather or not it has glass on both sides or in other ways... multiple materials.

In multihull's early days, (well not the EARLY days, which go back to ancient times), but recent early days... Like the 60s and 70s, most multis were built of plywood plank on frame, with thin skins and stringers. Most were trimarans, were not popular, and considered too expensive to mass produce at a profit. Most folks built it themselves, or bought it from the guy that did. This structure was covered with thin glass on the exterior for weatherproofness, and paint or wood preservative was applied on the inside.
They would last as long as you took care of the boat. We were, BTW, considered to be the "lunatics" of the boating world, and NOT welcome at the "yacht club".

Around the early 80s the WEST system came along and made a MUCH better boat. Being 100% mummified in epoxy, as well as exterior glass and glass or epoxy joining techniques, made a much stiffer more maintenance free structure. Dry wood stays light and stable! With both sides of thin plywood skins being coated, it also took on some characteristics of "I beam" construction. This made it a different animal, and the Gougeon Brothers, (of WEST epoxy), referred to these boats as well, as "composite".

On Our Searunner, the multiple chines themselves are all glass fiber inside and out, making it a true "composite" construction.

Before exotic construction materials, (Kledgacell foam, carbon, etc.), multihulls were best (or most often) made of either cold molded or plywood on frame construction, because an all glass multihull would be MUCH too heavy.

Now, the above two building materials, as well as, Cedar or foam strip plank, CC panels, Carbon/Kevlar, or foam core, would ALL be considered better multihull materials, over using solid glass. Weight is everything on multihulls, and if you make it too heavy, you ruin the boat.

Think of a fabric covered bi-plane. You can beef up the paper thin fabric skins to the point that a bird will no longer go through the wings on impact, but the plane will no longer fly!

In light weight multihull construction, "One Offs", or custom builts... IF they are done well, they have the best shot of having the beef "only" where you need it. Our boat for example, is mostly glassed with ONE layer of 4 oz glass. This is about like a piece of paper! It makes it vulnerable to hard dinghies pulling alongside, mooring ball rings, and dropping tools on deck. Otherwise... on the minikeel, (which can support the boat), the glass is quite thick, and the bottom is 3/8"! The stems, foil edges & bottoms, all seams, chines, and hundreds of linear feet of radiuses, are glassed in multiple layers of bi-axial. This puts IMPACT resistance where you really need it, only. STRENGTH from the sea's impacts, comes from the lightly glassed 90% of the structure, and IMPACT RESISTANCE to hard things, comes from the localized heavy glass buildups. Given a lifetime of care and maintenance of the skins, as well as paint, and EVERY major bolt hole having been lined with epoxy in construction, these structures will last every bit as long as a solid glass one. The custom "composite" will be considerably lighter, and probably stiffer as well, but less forgiving of ignoring maintenance. EPOXY IS VULNERABLE TO UV RAYS! You must keep it painted for it's entire life.

The same applies to more modern "composite" materials used in production boats. They will be stiffer and lighter than solid glass, and (properly designed), just as tough from impacts like flotsam or the bottom. They will, however, be a bit less puncture resistant in the UN reinforced areas where impact is neither likely or important.

One thing to remember, is that in identical designs, a lighter structure, lightly cruised, is higher off of the water and gets far less impacts than the heavier boat. (Think of the bi-plane analogy). The "stronger boat" may well be the one more lightly built, either literally, OR because it is under less stress.

Design also becomes VERY important. Wing clearance being at the top of my list. If a boat pounds constantly, the entire boat is breaking down, even if the hull can take it. The rig especially takes a beating!

IMO... The best multihulls are the top 10% of custom built "one offs", that are designed to sail rather than sell! They are generally VASTLY better/safer boats than solid glass. The handful of "EXPENSIVE" semi custom or full production multihulls, that are well designed for seaworthiness rather than palatial accommodation, and lightly built in modern composites, are in the same category of, VASTLY better/safer boats, than solid glass. These composites may be less maintenance than the first composite example, but cost three times as much to buy.

Enjoy the search,

Mark
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Old 12-06-2011, 07:56   #9
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Re: Why a composite cat?

Quote:
Originally Posted by Doodles View Post
When I look at a boat listing, say on YachtWorld, they list the hull as FG for fiberglass and C for composite. It's the composite other than fiberglass I'm interested in.
Very true and other posters have listed possibilities. However, that is simply insufficient information from Yacht World and you aren't going to get a useful answer. It could be any of the constructions mentioned, and how it is construced using that method (all can be excellent or poor for your purpose) depends on the specific boat. It is going to comedown to the reputations of the designer, builder, and surveyor unless you are interested in doing a lot of research.

I could add Kevlar honeycomb to the list (my last boat). It was still going strong at 30 years when I sold it.
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Old 12-06-2011, 08:07   #10
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Re: Why a composite cat?

Quote:
Originally Posted by Doodles View Post
When I look at a boat listing, say on YachtWorld, they list the hull as FG for fiberglass and C for composite. It's the composite other than fiberglass I'm interested in.
I have a feeling the "FG" boats are all actually "C", and that the person filling in the blanks on the form was a little confused. I think they are just trying to make it clear that it is not a wood or aluminum boat. While there are many cats with solid fiberglass below the waterline, I can't think of any "fiberglass" cat that is not cored above the waterline. Apart from a handfull of ply/cold molded or aluminum boats, pretty much all cats you will be looking at will be composite, using either balsa, foam or honeycomb as the core, with fiberglass skins.

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Old 12-06-2011, 08:47   #11
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Re: Why a composite cat?

A clarification... On US federally documented boats, a planked wood boat covered ONLY with paint, is listed as "wood". IF it is glass over plywood or over any other material, it is listed as "FIBERGLASS". (These are the "check one" instructions on the document, and "Composite" is not an option). It can be misleading.

Looking at listings... they use the paperwork as a reference, and it could actually be any number of hull materials, and still be listed as "fiberglass". You have to inquire!

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Old 12-06-2011, 13:05   #12
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Re: Why a composite cat?

I did a quick yachtworld search and noticed many fiberglass boats labeled composite that I knew were not constructed with wood like a Catana 50 and many more. The other posters are correct about the confusion, fiberglass is a composite and composites can include fiberglass. Personally I wouldn't focus on a wood core boat and I wouldn't discard it out hand because it is a wood core boat. They can be good and they can be bad, fast and slow just like fiberglass. Oops, I meant to say composite.
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Old 12-06-2011, 17:49   #13
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Re: Why a Composite Cat ?

Thanks guys for all the great replies, very helpful.

What I'm understanding here is that production boats are mostly made from fiberglass because using a mold is cheaper if there is going to be some sort of production run, whereas composite boat are generally one-offs or custom jobs. That may be a generalization but let me stick with that for a moment.

Now, it often seems to me that these one-off composites tend to be cheaper. Is it because they aren't well known, because of they are composites and not as popular, of questionable construction ... why? Or maybe it's just a misconception on my part.

Bottom line, if you were shopping for a cat would you consider one or stick with the fiberglass? And why?
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Old 12-06-2011, 18:30   #14
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Re: Why a Composite Cat ?

Some mold built production boats are "composite", because they are perhaps a glass lay up, then Kledgecell foam, then more glass, bagged up, and then vacuumed down to cure.

"Composite" just means multiple hull materials like glass & wood core, glass & foam core, carbon/glass Nomex core, etc.

"One off/custom built" means "not" a production boat. These "One off"s are often the very best AND very worst boats out there! Because they have less track record, banks and insurance companies are sometimes leery. This, and the fact that a lot of custom/one offs were someones first boat, or their own unproven design, and therefore not so good, has created an unusually low market value on the type. It is justified and fair regarding the bad ones, that's all they're worth. The really good ones, built by experienced builders to a well proven design, are worth several times what they often sell for! I have no idea the percentage here, but we,re talking less than half of them.

IF you do your homework to know what you're looking at, look around patiently and long, and then get a marine surveyor that knows the type, (like John Marples), then you might find a vastly superior "cherry" for half the price of a similar production boat.

As an example... This cold molded wood/epoxy composite "One off" work of art, was designed and built by a talented friend of mine and his wife. It eventually sold for a very good price, but 50% less than a similar production boat.

There is more risk, as you have no repercussions if you get a "rotten apple". This is why everyone and his brother are not doing it. I would, because I would go over it all day for two weeks to figure out what it really is.

Buying a custom is not for the multihull uneducated or timid, but you can otherwise get a hell of a good boat for a really good price this way.

Good luck with it,
Mark

BTW... there are some DAMNED expensive semi customs that are professionally built, like the Atlantic 42. This would be less risk, as there is a company there to complain to, but what goes with the "less risk", is double the purchase price up front. It would not be a better boat than a true "cherry" of a one off, just seemingly less risky.
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Old 12-06-2011, 18:42   #15
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Re: Why a Composite Cat ?

Doodles, You are correct in your conclusions. Those one offs are usually cheaper because they are unknown and I suspect one reason would be it would be harder to get financing on. With all the problems that production run cats have had I feel that most fears regarding one offs are unfounded. Take Hecla, a well known tri built out of cedar strips that has a proven race winning history. http://www.yachtworld.com/core/listi...g_id=1427&url=
Would I buy this boat? Hell yes. In a heartbeat. Would I buy a brand new one built by an unknown. Maybe, but I would scrutinize it more. Any boat requires careful consideration and those customs are probably even with production cats quality wise more or less. I think you've got a good grasp already. Good Luck
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