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

From: Michael Daly <michaeldaly_at_rogers.com>
Date: Fri, 06 Jun 2003 00:23:46 -0400
On 5 Jun 2003 at 21:44, jwd_at_acm.org wrote:

> Their justification was that gelcoat provides no
> structural benefit to the boat, and going without it saves 5-8 lbs of
> essentially useless weight. 

Not true.  The gelcoat increases the thickness of the hull and 
provides for greater stiffness.  Without the gelcoat, you're more 
likely to get oilcanning and possibly buckling at the limit of what 
the kayak can handle. (Unless you beef up the fibre and resin, which 
negates some or all of the weight saving.)

> I guess it protects the glass or kevlar fiber from UV
> exposure (does current generation fiberglass and kevlar fabric NEED UV
> protection?). 

Fibreglass does not, but Kevlar and _the_resin_  need protection.  At 
the very least, building without gelcoat means adding a UV coating.  
Varnish works and is used on strippers with exposed resin.

The gelcoat also protects the resin and fibre from impact and 
abrasion.  With the gelcoat, you've got a sacrificial layer.  Without 
the gelcoat, the damage is done to the resin and to the fibres 
directly.  I'd rather not see damage to the main structural element 
in the composite.

> I also know that some in the industry, Tom Derrer of Eddyline among
> them, have staked their reputation (and their business) on foregoing
> gelcoat.  But even Eddyline's high-end "modulus" boats, which are
> vacuum bagged glass/kevlar composites, still use a Carbonlite
> (polycarbonate?) shell on the outside.

Six of one, half dozen of the other.  Polycarbonate is a very tough 
plastic, but it still scratches.  I'd rather get regular construction 
and know I can fix it.

The only folks that see a real advantage in kayaks (or canoes) 
without gelcoat are the racers.  They are willing to sacrifice the 
gelcoat in order to save a few pounds.  The rest of us have little 
need for dropping a few pounds from our kayaks.  

Next time you see these kayaking friends, check to see if they are so 
buff that they couldn't lose 10 lbs weight and be more fit!   Unless 
they're national team calibre, their likely wasting time and money on 
an ultralight boat.

Mike

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Received on Thu Jun 05 2003 - 21:19:37 PDT

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