"DSK" wrote in message
...


I have a buddy who used to have a 100% chopper gun canoe. Weighed about
200#.

That must have been fun to portage.

OK, it may be that you've spread the compression over a large enough area
that it's not a problem. But there will be a concentration of stress at
the edge facing the direction the line pulls from.

It was installed three years ago and so far no evidence of any indentation
on the forward edge (facing the mast--it's a main halyard stopper).

Hey if it works, it must have been done right!

Beginner's luck, and a bit of overkill, according to the glass wizard at our
marina.

From what I've read, the issue is bonding the skin to the core. Airplanes
use some exotic technology to achieve this, and it could be done (I
believe it has been done) with some high end boats for critical
components. The easiest way to get a good bond is to fill the cell with
resin, but then you don't have such a light structure any more!

I found a website which claimed that Yamaha built a few prototype sailboats
with honeycomb aluminum coring throughout the hulls and on the flats of the
decks. It was great, according to the author, but the cost would have been
prohibitive. As for bonding the skins to the honeycomb, Hexcel Skis, which
used the technology, used to laminate the skins first and then apply a
slurry of resin and finely chopped fibers to the surface, into which the
honeycomb was pressed. Both inner skins were applied simultaneously and
bonded under high pressure--I vaguely tend to recall that it was about
150psi. Hexcel warranted the skis against delamination from the core for
life. My wife had a pair--they were light and responsive, according to
her--and we eventually threw them away after they hung in the rafters of the
garage for a decade or so after she'd gotten several new pairs of skis.
They never delaminated, but all my older French skis did--Rossignol, Dynamic
and others all used wood cores.

Max

I have a buddy who used to have a 100% chopper gun canoe. Weighed about
200#.


Maxprop wrote:
That must have been fun to portage.


Didn't. It rode on a ski boat trailer. The guy worked in a
fiberglass plant making bathtubs & such, and brought in a
canoe to use as a mold plug. He wanted to make a sailboat
but the canoe was not enough of a success to justify the work.


I found a website which claimed that Yamaha built a few prototype sailboats
with honeycomb aluminum coring throughout the hulls and on the flats of the
decks.

Yamaha builds some cool boats. They're currently making a 30
(IIRC) and a 33' sport boat that looks at least as fast and
more practical than anything else on the market,
unfortunately I've lost the web page & can't find it again.

There have been some "superyachts" built with structural
panels (floors & partial bulkheads, I think) with aluminum
honeycomb core.

... It was great, according to the author, but the cost would have been
prohibitive. As for bonding the skins to the honeycomb, Hexcel Skis, which
used the technology, used to laminate the skins first and then apply a
slurry of resin and finely chopped fibers to the surface, into which the
honeycomb was pressed. Both inner skins were applied simultaneously and
bonded under high pressure--I vaguely tend to recall that it was about
150psi.

The ones I read about used a different adhesive than
laminating resin to glue the core to the skin,
vacuum-bagged, then post-cured the whole structure (as I
understood the process). It's not a mature technology, but
it's hard to imagine what's coming up next by the time they
get this stuff completely figured out.

I've been working with some carbon fiber & foam core
laminations, learning enough to make a dinghy out of the
stuff. It's amazing, weighs nothing. A friend had a new
Int'l 14 hull made in a pro shop, then brought it home to
install the hardware. Could pick it up with one hand and
throw it across the yard like a huge paper plane!

Fresh Breezes- Doug King

"DSK" wrote in message
.. .
I have a buddy who used to have a 100% chopper gun canoe. Weighed about
200#.


Maxprop wrote:
That must have been fun to portage.


Didn't. It rode on a ski boat trailer. The guy worked in a fiberglass
plant making bathtubs & such, and brought in a canoe to use as a mold
plug. He wanted to make a sailboat but the canoe was not enough of a
success to justify the work.


I found a website which claimed that Yamaha built a few prototype
sailboats with honeycomb aluminum coring throughout the hulls and on the
flats of the decks.

Yamaha builds some cool boats. They're currently making a 30 (IIRC) and a
33' sport boat that looks at least as fast and more practical than
anything else on the market, unfortunately I've lost the web page & can't
find it again.

There have been some "superyachts" built with structural panels (floors &
partial bulkheads, I think) with aluminum honeycomb core.

... It was great, according to the author, but the cost would have been
prohibitive. As for bonding the skins to the honeycomb, Hexcel Skis,
which used the technology, used to laminate the skins first and then
apply a slurry of resin and finely chopped fibers to the surface, into
which the honeycomb was pressed. Both inner skins were applied
simultaneously and bonded under high pressure--I vaguely tend to recall
that it was about 150psi.

The ones I read about used a different adhesive than laminating resin to
glue the core to the skin, vacuum-bagged, then post-cured the whole
structure (as I understood the process). It's not a mature technology, but
it's hard to imagine what's coming up next by the time they get this stuff
completely figured out.

I've been working with some carbon fiber & foam core laminations, learning
enough to make a dinghy out of the stuff. It's amazing, weighs nothing. A
friend had a new Int'l 14 hull made in a pro shop, then brought it home to
install the hardware. Could pick it up with one hand and throw it across
the yard like a huge paper plane!

I've wondered why carbon fiber hasn't been exploited more as lamina in
production boat hulls and decks, such as class racers, etc. If utilized in
mass quantities, the high cost factor should be mitigated somewhat. And how
about a carbon honeycomb core? Shouldn't present the bonding issues that
aluminum honeycomb did.

Max

Maxprop wrote:
I've wondered why carbon fiber hasn't been exploited more as lamina in
production boat hulls and decks, such as class racers, etc. If utilized in
mass quantities, the high cost factor should be mitigated somewhat.

It is being used more & more for spars, especially sprits &
spinnaker poles, also foils. For example Hobie Cats have
been using carbon fiber rudder blades for years.

The cost of the raw material just took a leap upward,
supposedly the military is buying up 110% of production for
the next few years. Fortunately I had already bought some
rolls of woven carbon for my dinghy project, I think I have
enough.

.... And how
about a carbon honeycomb core? Shouldn't present the bonding issues that
aluminum honeycomb did.


There is an expanded carbon core material, but it has to be
carved to shape. Difficult to work with. And it's *real*
expensive.

Fresh Breezes- Doug King