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Old 27-11-2007, 11:38   #1
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Epoxy and Vinylester

Catamaran forum:

A client of mine sent me a thread posted by someone on why more catamarans are not built from epoxy? And why in his view they all should be.

First off, epoxy now is very expensive, and most epoxy boats must be postcured and later spray painted. This makes for a lighter boat, for sure, but the spray finishes never hold as long as gelcoat. It is very hard to build a boat in production in this fashion as well.

Vinylester in my view is the best option right now as it is nearly impervious to water incursion (they make water pipes from the stuff!) and can be laid up in female tooling and gelcoated easily. Many builders will offer a vinylester upgrade if you ask for it and pay for it.

Polyester is the resin of choice for production builders because it is a lot cheaper than vinylester or epoxy and the majority of new cat buyers are terribly unsophisticated and shopping on price for the most part. You can build a poly boat, with balas core, and marine ply bulkheads for a lot less than you can build a foam core vinylester boat or a foam core epoxy boat. And since the poly/balsa boat is heavier, the hulls must be wider to handle the extra weight - but, guess what, most buyers want all that extra space! So they get "more boat for less money." What they also get is a slower boat and a less durable boat over time. But, again, if getting the best price and the most space for the money is the short term goal, a poly/balsa/ply boat is the way to go. Hard to argue with the success of Moorings or Lagoon!

From a cost benefit standpoint I think vinylester is the way to go right now.

But if you get a poly boat, make sure it has a great epoxy barrier coat and you bottom paint your boat regularly and do a new barrier coat job every five years to be safe.

Phil Berman, President
The Multihull Company

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Old 27-11-2007, 13:57   #2
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welcome Phil, to our prestigious group

Denny and Diane
Lagoon 37
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Old 27-11-2007, 16:21   #3
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Vinylester, in my experince (albeit, limited), is fine for laying up glass, but not great for fairing and absolutely lousy for gluing.
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Old 27-11-2007, 22:40   #4
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First of all, welcome to the board.

Originally Posted by Phillip Berman View Post
Catamaran forum:
This makes for a lighter boat, for sure, but the spray finishes never hold as long as gelcoat.

Phil Berman, President
The Multihull Company
This topic has been previously discuss and I believe there were statements about well painted hulls lasting much longer than gelcoat. My experiece was that a dark colored gelcoat in the tropics really broke down in about a year. I've heard fastcat435 suggest a well painted epoxy boat looked good as new 5 years later. Just curious if you can elaborate on your experience/opinion on gelcoat holding longer than spray finishes.

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Old 29-11-2007, 14:01   #5
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We just discussed this pretty exhaustively

- People who say it cannot be done should not interrupt those who are doing it. -George Bernard Shaw
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Old 01-12-2007, 07:16   #6
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I agree, it's been discussed very thoroughly. Also, charter boats have very different needs than owner boats.

1) Speed would be a detriment in a charter boat as it would mean it would be also more prone to flipping and collisions would be at higher speed and damage. The couples fly to the charter and from day one the boat is in a great location. For an owner boat, they intend to sail to different locations and speed and passage making are far more important.

2) Charters look for large accomodations to be able to distribute the costs renting the boat among 4 charter couples, for owner designed boats those huge accomodations are at the cost of having large areas of reserve bouyancy for safety and reducing the size of the galley and storage for having births that would sit useless 99% of the time and often have to be retrofitted into storage.

One thing I think that charters do contribute to the advantage of catamarans is access for repairability. I often marvel at the well thought access panels and conduits on many boats like the moorings.
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Old 02-12-2007, 00:42   #7
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Welcome to the forum Philip and good to hear from you.
You are right from a cost perspective Vinylester is a good choice , however if weight and strenght come into play epoxi is the choice.You are also correct that it is far less labor intensive to build a gell coated Yacht .
I strongly disagree to your statement that a Spray painted boat does not hold as long or nice as gellcoat. To the contrary with gellcoat especcially on a cat very fast hair cracks appear and discoloration is also a issue with gellcoat, If repairs need to be done to gellcoat surface it always shows a different color .
Also see the Epoxy thread

Greetings Gideon

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