I've recently stumbled acroos these folks:

http://www.precisionboard.com/Mar/

who offer a High Density Polyurethane board, in various desities and
thicknesses. To quote fom the site... "Precision Marine Board is
ideally suited for components such as decks, stringers, transoms, fish
boxes, livewells, and all other areas that require a high strength,
light weight and high durability material."

I then consulted Hankinson (Fiberglass Boat Building for Amateurs) who
says that Urethane foams are too firable to be used as a structural
core material, recommending instead linear or cross-linked PVC (Airex)
or extruded polypropylene (Nida Core).

My immediate need is bulkheads, though I'll eventually get to decks.

So... what gives? Is the Precision Board - as a 'poly' urethane -
different from the urethane foams of yesterday? Is it, in fact
suitable for ..."decks, stringers and transoms..."?

Any insight would be appreciated.

Mike Worrall
Los Angeles

I have used foams for this purpose in the past and they all worked well for
me, but the real danger is water/liquid intrusion. They all absorb to some
degree, which makes repairs impossible. In that light, any structure that is
expected to maintain some element of value over time, should never be made
using any foam. Your call, my 2 cents.
Steve

"mike worrall" wrote in message
m...
I've recently stumbled acroos these folks:

http://www.precisionboard.com/Mar/

who offer a High Density Polyurethane board, in various desities and
thicknesses. To quote fom the site... "Precision Marine Board is
ideally suited for components such as decks, stringers, transoms, fish
boxes, livewells, and all other areas that require a high strength,
light weight and high durability material."

I then consulted Hankinson (Fiberglass Boat Building for Amateurs) who
says that Urethane foams are too firable to be used as a structural
core material, recommending instead linear or cross-linked PVC (Airex)
or extruded polypropylene (Nida Core).

My immediate need is bulkheads, though I'll eventually get to decks.

So... what gives? Is the Precision Board - as a 'poly' urethane -
different from the urethane foams of yesterday? Is it, in fact
suitable for ..."decks, stringers and transoms..."?

Any insight would be appreciated.

Mike Worrall
Los Angeles

"Steve Lusardi" writes:

I have used foams for this purpose in the past and they all worked well
for
me, but the real danger is water/liquid intrusion. They all absorb to some
degree, which makes repairs impossible. In that light, any structure that
is
expected to maintain some element of value over time, should never be made
using any foam. Your call, my 2 cents.

And where did that come from?

Lonza, makers of Airex, for one, probably would take exception to your
statement.


--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures

Lew,
Lurk here for a couple of years and count the number of threads that
reference just that problem. As long as there is no exposure, the problem
doesn't exist. When there is exposure, the extent of liquid migration is not
determinable. In the end, total removal and replacement of the foam is the
only certain repair and the cost can be unaffordable for large sections like
sandwich hulls.
Steve

"Lew Hodgett" wrote in message
hlink.net...

"Steve Lusardi" writes:

I have used foams for this purpose in the past and they all worked well
for
me, but the real danger is water/liquid intrusion. They all absorb to
some
degree, which makes repairs impossible. In that light, any structure
that
is
expected to maintain some element of value over time, should never be
made
using any foam. Your call, my 2 cents.

And where did that come from?

Lonza, makers of Airex, for one, probably would take exception to your
statement.


--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the
Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures

"Steve Lusardi" writes:

Lew,
Lurk here for a couple of years and count the number of threads that
reference just that problem. As long as there is no exposure, the problem
doesn't exist. When there is exposure, the extent of liquid migration is
not
determinable. In the end, total removal and replacement of the foam is the
only certain repair and the cost can be unaffordable for large sections
like
sandwich hulls.

They above does not apply to Airex used in hulls, including mine.

Maybe that is why it is 2X-3X the cost of other foams.

Airex is also why I use the tag line, "The Bullet Proof Boat" in my SIG
file.

--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures