: Hi Mike,

: Not withstanding your argument that it isn't that much glass, wouldn't you
: agree that a kayak deck will see a lot less rough service that a kite sail
: board? I don't know anything about foam core but I would think any of the
: more conventional layups with the reinforcements we see on wood core decks
: would be strong enough, and lighter than multiple layers of 6 oz glass. It
: is being built for speed rather than expedition use after all. Besides, if
: the board has 3 layers all around, how does that work out on the deck in
: question? One outside two inside? Vice versa? 3 in and out? If I
: understand core construction correctly the interior and exterior skins of
: glass provide the structure while the core provides a space between those
: skins to enhance the performance, and for the home builder, the form on
: which to build those skins. Even an all composite boat has a core of some
: description, like several plies, a different fabric, mat rather than woven
: glass, or combinations of the above and honeycomb or foam between the
: skins.

: Perhaps some experimenting is in order to see if strip deck type layup is
: tough enough for the task at hand.

: Tom

Hi Tom,
I was comparing the amounts of glass between the board and the kayak, taking that the kayak is hollow structure where the inner surface is glassed as well as outer. If you take the number of layers and weights of glass from the lowest and highest part of each craft, a kayak actually has more weight of glass than a board.

The fact that boards take a hammering in use and they don't break all that often makes what is used on a kayak seem a bit of over-kill. I believe in over-engineering a bit.

For a boat deck, from memory, Half inch PU foam with one layer of woven, one layer CSM on one face and one layer of CSM and two layers of woven will have minimal deflection in a 3 foot span, using polyester resin.
This would not support a deck mounted mast without a sub-deck pillar and hardwood core replacement.
CoreCell with epoxy/glass would be stronger with the same schedule.

If the board has three layers all round, then the deck would have three on top and three underneath if you glued the board onto a hull as a deck.

Mike Savage
South West Cork