RE: [Paddlewise] Spare the gelcoat -- pros & cons of skin-coat boats

From: Severn Clay <severnclay_at_earthlink.net>
Date: Fri, 6 Jun 2003 09:07:01 -0400
* While having a wide ranging conversation recently with a fellow sea
* kayaking enthusiast, the person made a statement that surprised me a
* fair bit.  They said that they've ordered their recent boats, whether
* for race use or not, WITHOUT gelcoat (these are fiberglass or kevlar
* composite boats).  Their justification was that gelcoat provides no
* structural benefit to the boat, and going without it saves 5-8 lbs of
* essentially useless weight.  When queried about what they did about
* repairing the inevitable dings, they said they just used clear epoxy.
*
* So, I got to wondering about the pros and cons of going with a skin-coat
* hull (or hull and deck) configuration.  What do Paddlewise people think
* of the idea?  Any direct experience with it?
*
After building a stitch-and-glue boat, which is essentially a composite
sandwich construction, I've been wondering about other sandwich materials.

Lightweight airplane parts are  constructed of glass (fiber- or graphite-)
around a lightweight core.  Has anybody tried this with kayaks?  Granted,
the abrasion-resistance needed in a boat is much higher, but it seems that a
laminate of just fiberglass, with or without gelcoat, is a really
inefficient use of the materials.  I'm imagining either foam core panels
laminated on both sides with glass, or a layer of glass coated with some
sort of two-part foam, covered with a layer of glass on the inside.  You
could even "tune" the lay-up in higher-stress areas with layers of kevlar or
graphite.

I think one of the ideas behind a composite construction is to spread the
structural requirements over a larger area, rather than concentrating them
on individual structural members.  In any case if a ding is causing
structural failure, something is wrong.  This works in skin-on-frame boats
as well because the joints aren't rigid, so they have some give and spread
stress around the frame.

Clear varnish or paint provide UV protection for fiberglass.  I think
repairing dings on fiberglass alone is probably easier than repairing
gelcoat.  All that fuss over a shiny paint job...  of course, if you don't
HAVE to drag the boat down the beach because you can carry it on your
shoulder...

Severn



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Received on Fri Jun 06 2003 - 06:07:12 PDT

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