Back in the early 1980's Eddyline didn't use gelcoat on their vacuum-bagged kayak hulls. The color was put in the resin with translucent dyes. The boats were as strong as they would have been with gelcoat but were lighter (and I assume given the relative costs of gelcoat and dye, less expensive to build). So why did they start using clear gelcoat (at first on the decks and then also gelcoat on the hulls a little later)? I don't know for sure, it wasn't my decision, you'd have to ask Tom Derrer about that. For years before switching totally to Carbonlite exteriors, Eddyline used gelcoat on both the hulls and decks and their kayaks lasted a lot longer and had better resale value because of it. I suspect Tom's decision had something to do with how those no gelcoat boats were aging. The problem was that after a few years of sun exposure the surface resin eroded ever so slightly. The pressure from the vacuum-bagging process had plastered a lot more of the glass fibers up against the mold surface during construction so it didn't take much erosion to expose significant amounts of glass fiber on the boats outside surface. Have you ever seen one of these no gelcoat kayaks? You'll recognize them by the silvery, sparkly sheen on their surface. Touch the surface with a tender area of your skin and you'd get the fiberglass itch from all those little needle sharp slivers. The more weathering the boats got the quicker this would happen. This would happen to hand laid boats with no gelcoat as well, but it took a little more weathering for them because the glass fibers only touched the mold surface at the points where the cloth's weave touched it. When it happened though, the hand-laid "skin coat" kayaks would look like they were covered with a rash of glass fiber spewing pimples/mini-volcanoes every 1/8th inch or so across the surface. The had the same itch too. If only stored indoors and out of the weather, the non-gelcoat kayak can last a long time before this happens. Kirk Olsen's experience with his canoes is an example. His first is ugly but the ones he always keeps covered or indoors have aged very well. Clear gelcoat can be sprayed on thinner without the need to worry about good coverage (with pigmented gelcoat it must be thick enough so you can't see through it in places, making it look mottled). These clear gelcoat kayaks can be somewhat lighter than some of the pigmented gelcoats but not as light as with no gelcoat. Don't mistake them for non-gelcoated boats though just because you can see the glass weave through them. Given the same kayak lay-up they are also a little more flexible because their are no reinforcing fibers in clear gelcoat as there is in pigmented gelcoat and the laminate (including gelcoat) is a little thinner. I think getting a thin even coat of gelcoat on the mold without much of it running down and pooling into the bottom of the mold (eventually becoming a thick brittle part of the boat) takes quite a bit of skill. Most of the kayaks I've seen from Europe are mainly constructed (especially the decks) with chopped strand glass mat, the most brittle of fiberglass construction materials used in kayaks (because they are very resin rich). The mat conforms around recessed fittings much better than the stronger more expensive materials with a hand lay-up. Most kayaks I've seen that were imported from England get good strength and stiffness on the deck by making the chopped strand mat laminate on the deck very thick, but that also translates into a very heavy kayak. Those that attempt to make the mat decks thinner and lighter end up with a very brittle kayak. To my mind by far the biggest benefit of gelcoat is the UV protection and long-term itch free environment it provides the user. Speaking of the environment, it is clear that gelcoat gives off some styrene fumes before it cures and that makes its use in kayak building much more expensive to meet government regulations for a spray booth and fans and filters and periodic inspections by the EPA. My question is: does polycarbonate give off any potentially toxic chemicals in any stage of its manufacture or use. It is my understanding that polycarbonates can leach out some chemical that mimics a female hormone and that some folks are now warning against its use for water containers for that reason. Matt Broze www.marinerkayaks.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Sat Jun 07 2003 - 07:37:42 PDT
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