On Fri, 07 Jul 2006 04:41:35 GMT, dog wrote:

This is probably a really bad idea for several reasons.

1) The thermal expansion coefficient of metal is far greater than that
of foam, wood or fiberglass. The heating and cooling cycles will cause
stress cracks and delamination.

My data book gives linear thermal expansivities as follow:
glass 8 to 9 X 10-6 /degC
epoxy resin 39 X 10-6/degC
18/8 stainless 16 X 10-6 /degC
Aluminum 23 X 10-6/degC
Bronze 17 X 10-6/degC

Hardwood 10 X 10-6/degC on up....

Plastics 80 to 240 X 10-6/degC

Seems like they are all in the same ball park except the plastics in
general?

Brian Whatcott Altus OK

Interesting numbers. We typically use a glass reinforced epoxy which would
seem to put the composite's coefficient somewhere between 8e-6 and 39e-6.
The average is squarely on top of aluminum's 23e-6.

Roger (I'd put the reinforcement under the deck, myself)

http://home.insightbb.com/~derbyrm

"Brian Whatcott" wrote in message
...
On Fri, 07 Jul 2006 04:41:35 GMT, dog wrote:

This is probably a really bad idea for several reasons.

1) The thermal expansion coefficient of metal is far greater than that
of foam, wood or fiberglass. The heating and cooling cycles will cause
stress cracks and delamination.

My data book gives linear thermal expansivities as follow:
glass 8 to 9 X 10-6 /degC
epoxy resin 39 X 10-6/degC
18/8 stainless 16 X 10-6 /degC
Aluminum 23 X 10-6/degC
Bronze 17 X 10-6/degC

Hardwood 10 X 10-6/degC on up....

Plastics 80 to 240 X 10-6/degC

Seems like they are all in the same ball park except the plastics in
general?

Brian Whatcott Altus OK

Brian Whatcott wrote:
On Fri, 07 Jul 2006 04:41:35 GMT, dog wrote:

This is probably a really bad idea for several reasons.

1) The thermal expansion coefficient of metal is far greater than that
of foam, wood or fiberglass. The heating and cooling cycles will cause
stress cracks and delamination.

My data book gives linear thermal expansivities as follow:
glass 8 to 9 X 10-6 /degC
epoxy resin 39 X 10-6/degC
18/8 stainless 16 X 10-6 /degC
Aluminum 23 X 10-6/degC
Bronze 17 X 10-6/degC

Hardwood 10 X 10-6/degC on up....

Plastics 80 to 240 X 10-6/degC

Seems like they are all in the same ball park except the plastics in
general?

Brian Whatcott Altus OK

Honestly, I don't know how to read that thermal expansion coefficient
table. I assume you mean that the expansion rate of a 18/8 stainless
steel metal is close to epoxy resin, and we should not need to worry
about the difference in their expansion rate. I guess this may explain
the reason why people use epoxy as a bedding to secure metal fitting
onto the boat in addition to metal fasteners. Great! This means I can
embed the whole metal plate in epoxy instead of free-floating it, and I
will have one less thing to worry about. Thanks for the info.

Jay Chan