Michael O'Dell wrote:

In article ,
"Allan" wrote:

Hi. I'll probably get some thoughts on this. I built a 20' Osprey Triple
kayak using epoxy resin. Nice boat. Now I'm building an 18' Trident Power
Cat ( johnsboatstuff.com ). He's recommending epoxy for structural work and
polyester (either orthothalic or the other one, I can't remember right now,
would have to look at my plans) for glassing up. Anyway it's the "better"
polyester. I like the price of the polyester, but..................

Anybody have any thoughts on why I should go all epoxy or use the
epoxy/polyester combo??? Thanks for any comments, thoughts.

Amateur 2nd boat builder in the Great White Frozen North,

Allan



build in epoxy - period.

polyester has no secondary bond strength and not
a lot of primary bond strength. epoxy is not
that much more expensive and could well save
your boat. epoxy actually sticks to the glass
where polyester does not; it merely hardens
*around* the glass fibers. that's why a polyester
laminate peels apart along the surface of the
reinforcement when it goes into failure.

-mo

I guess that's why all my 30 year old poly boats just collapsed
into piles of hairy dust in my backyard, eh? Zero strength, eh?

How do you calculate the cost benefit from this supposed longer
life for epoxy, given that the life span is still generally
indeterminate for both types under reasonable stresses? I have
heard of very few poly boats disintegrating in any remarkably
shorter time than epoxy, even in contests involving rocks and
stuff.

Such extremeist statements suggest you must be a berserker stock
market manipulator with interests and positions in the epoxy
chemicals market bordering so extremely on the insane as to
suggest you sell epoxy mainly to be able to continue to dispose
of toxic chemicals added in small amounts to the resins, just
like some shampoo vendors I suspected of doing just that until
your arguement was so strongly stated and foolishly revealed ;-)

Now, as far as skin irritation and developed allergies and
consequent lifetime sensitivities and costs associated with
respirators, deformed babies, etc, I would favour poly quite
strongly for a hobby builder, especially a relatively
inexperienced one, especially for a first build. Commercially,
the evidence is overwhelming. I cannot imagine anyone smart
enough to be able to afford the costs of epoxy being insensitive
to those cost benefit analyses so evidently performed and adhered
to by professional builders.

You just try to get an informed professional to build in epoxy
and then count the costs.

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