Nowhere close to being as heavy. Even with fiberglass, it's less dense than
water. (It floats.) Steel ranges from 7.5 to 8 times as heavy as water.
(It sinks.)
If you laminate the pieces with filled epoxy, it will be better than a solid
beam because you will get rid of the defects (knots, splits) and "cross"
them with defect free pieces.
Roger
http://home.insightbb.com/~derbyrm
"Thomas Wentworth" wrote in message
news:INDsf.1413$SW3.595@trndny08...
Is plywood as heavy as steel? If you cover it with fiberglass?
For the backbone ... can you use wood that is put together rather than a
solid beam?