noseoil wrote:I used 5/16" elevator bolts for my build, plus a couple of carriage bolts when I couldn't find long enough elevator bolts. It's way-overkill, but 3 per side on the frame & 3 more in the middle at different points. Elevator bolts have larger heads & a square shank, so it's like a washer counter-bored into the wood surface.
Grade 8 bolts are overkill, they're used where excessive forces are concentrated in the loads being carried. They are a much stronger alloy than common hardware store bolts, which are plenty strong enough anyway. The grade 8 alloy is rated at 150,00 psi!
I would use white oak if you're concerned about a good rot-resistant hardwood. Strong, tough & heavy, use it sparingly. I used red oak for my hatch spars, as I wanted the higher fiber strength of oak to hold fasteners for the hinges. Poplar is too soft. The lower deck framing is just poplar at the frame. Not too worried about the bolts pulling through. If that happens, we have other problems to deal with.
Thanks, white oak it is! Only gonna use it on the hinges and a piece at each of the three attachment points to the frame. My bolts will be attached to steel gussets on the frame, rather than through the tube steel. Will E using standard pine framing on top of the frame rails/crossbars, and will tie in the oak above the gussets.