Fasteners as well as epoxy at sheer/deck joint?

I'm decking over my 19' sportboat with a 1/4" plywood layer and then another laminated layer of 1/4" meranti strips. With first ply subdeck down via drywall screws and fender washers as clamps -- I'm wondering if I should also put stainless screws into the sheer/deck clamp -- it's 1/2" cedar sheathed on the outside laminated to a 1/2" x 2.5" meranti strip on the inside -- so a 1 1/4" #6 or 8 will go. The scantlings also call for an 8" tape to cover the seam -- are the screws overkill/unecessary wieght?

 

This sounds to be a pretty heavy deck, for a sport boat. If the screws are hitting the cedar, they will not have much holding power. This sounds like a cedar strip hull, with a meranti sheer clamp. You'll want to hit the clamp with the screws and they will provide a lot of sheering load strength, plus the pull out needs of the deck. Fillets and tape are your real structure, the weight of a few fasteners shouldn't effect anything.

 

I have acquired the wood screwing habit of drilling the screw pilot hole, running the screw all the way in, back it out, put 2 or 3 drops of THIN instant glue down the hole. Wait 1 hour, final run in of screw. Should the screw be too tight? Out, bar soap on the first 1/2 of threads. Pratice on scrap first. Never know you have weak wood or bad grain direction.

 

1/8" and glue or epoxy of the strips is overkill, if the deck has any upward bowing in it with curved deck supports under it. 3/8" total ply is the siding thickness for wood runabouts up to 50 mph.