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From: (no name) (no email)
Date: Fri Mar 23 2007 - 09:59:00 EDT
In a message dated 3/23/07 12:01:11 AM, Brian writes:
> Gotta agree with Bob England on this statement - if the vessel is truly
> cold
> moulded (multiple layers or strips saturated with epoxy) as opposed to
> stitch
> and glue or epoxy over wood with a bit of glass cloth, then there are
> multiple
> advantages over a frp hull. This assumes the builders know the trade.
>
> Strength to weight ratio - substantially over fiberglass (some say 4 times
> stronger 1/2 the weight).
> Sound dampening and insulation.
> Superior Impact abortion - unlike a glass hull, since the primary material
> is
> wood, it will crush rather than shatter.
> Fairly user friendly to repair if damaged.
>
Greetings Brian,
What you are talking about is not traditional cold molding but the Gougeon
Brothers (West Epoxy) resin impregnated wood process. In this process wood
strips are saturated with epoxy then laid on a male mold. The hull retains the
strength and lightness of the wood but is almost immune to the problems of
moisture absorption and rot. I believe that the Gougeon Bros. process was originally
developed during the '50s to fabricate rotors for wind turbines and
helicopters.
Traditional cold molding is an earlier technique that was used primarily to
make lightweight racing dinghies and aircraft prior to, and just after WW2.
Both the British Mosquito night fighter and the Hughes Spruce Goose had many
cold molded sections. In this earlier technique thin strips of wood veneer were
glued on a mold with a resorcinal or urea formaldihyde type glue. This glue
has excellent moisture resistance but no gap filling properties so the strips
had to be clamped or stapled in place until the glue cured. In terms of
strength, stiffness, and weight, wood is a superior boatbuilding material but
unfortunately tends to deteriorate if left out in the weather. We rarely see
traditional cold molding used in boatbuilding today because, for most purposes,
fiberglass construction is cheaper and more weather tolerant, although heavier.
Both cold molding techniques are very labor intensive and thus expensive. The
real advantage is that they permit a very strong and light hull to be built
with complex curved sections out of wood, a relatively straight growing and
stiff material.
The cold molded dinghies I used to race were fast and attractive, but they
required as much maintenace as other wooden boats. Trust me on this.
Larry Z
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