I'm pretty sure that that's disallowed :-(

Check and make sure. Cement has very little tensile strength. You really
can't build a thin shelled cement structure without some reinforcement.
Glass fiber is denser than water so it will not add any buoyancy.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com