Deck beams out of laminated plywood?

[imported_Paul VandenBosch]

I made up a deck beam for a small boat (Paradox), epoxy laminated out of six 1" strips of 1/4" ply, to make a 1" x 1-1/2" beam, as specified by the designer. The beam seems plenty stiff and its span is 4 feet or less.

Has anyone ever laminated deck beams or similar type structure out of plywood? Any concerns with this method?

The beam has to hold nails/screws, and the plywood laminates are lined up so the nails go in the face of the laminate, not the edge (which
should be good).

I'm using exterior ply, which is similar to the rest of the ply in the boat.

Paul V

[Phil Young]

I'd have thought one of our purists would have some words to say about this. I think engineering wise the use of ply is not ideal, because half your grain is running the wrong way, and so adding no real strength. Its almost going to a different principle where you would have a strong skin on the top and bottom, and just a spacer in between, like an I beam. But the ply makes a pretty heavy spacer, and the scantlings for that would be different. But I'd bet what you've done is structurally fine. Only real problem would be the potential for ingress of water through all the exposed end grain. Why not jusy use real wood? There's no benefit in using ply, unless maybe its scrap off the floor. Even then, for a 4' beam, go crazy, spend the momey on real wood.

[On Vacation]

Depending on the crown of the deck pieces, you will end up with weak beams if it is too great with solid pieces. Nothing wrong with lamination of plywood as long as you have wet out the plywood before clamping it up to glue. Even though the grains are turned differently, it creates a solid wood laminate.

We sandwich or scab on it sides pieces of plywood to reinforce the deck beams laminated with even solid wood.