Reinforcing Bench Seats

[DTro]

I have a 14ft starcraft with three bench seats in it. I have mounted quick release brackets to the front and back benches and intalled seats. I mounted the brackets simply by screwing directly to the benches. The benches are thin aluminum filled with foam. I'm roughly 200lbs and the alum seems to flex quite a bit when leaning back or rotating.

Any tips or suggestions on making a good secure modification.

My thought was to take a good marine grade plywood (maybe 3/4") and run that the length of the bench, screw that to the bench (any better way?) and then screw quick release to the plywood.

Thoughts?

[Polar Bear]

dtro, This summer I replaced the plywood seats in my Lund with the Trex brand synthetic decking material. I had to order the facia board to get the full 12 inch width needed for the seats. I comes in several colors, cuts and drills like wood but is made from a plastic, wood matrix.

The stuff is rot proof and never needs sealing or maintainance of any kind. Its virtually indestructable.

[DTro]

wow what a great idea. I never thought of that. Even be more sturdy at 5/4. Also rounded corners.

Now, what's the best way to attach to the bench? Deck screws?

[Surface Tension]

I like PB's suggestion. I find bench seats to be too low anyway so the extra 1 1/4 is nice. Now you can spread out your screws past the swivels base and along the entire bench seat.

Without using the board theres a couple ways to anchor into thin material with an expanding anchor or a toggle bolt.

If you have a sheet metal shop around you can have them make you a plate the width of your bench with 1 1/2 brakes that fold over the edges of your bench. Attach a mounting block to that then screw the plate into the side of your bench instead of on top. This changes the forces the screws are subject to and also wider anchor points.

Or remove the bench and carve out the foam to place a backer plate.

[Polar Bear]

Yep, Stainless screws. Very expensive but no corrosion.

[Steve Bakken]

ST's idea is definitely your best fix. If you're not feeling that ambitious, a good thick piece of plywood with alot of screws will be your next best thing. Pre-drill your hole in the plywood so that the threads of the screw will slide through, using a screw every few inches will help distribute the stress over a larger area, and use the afore-mentioned stainless machine screws. After 20+ years in the boat repair business, that recipe hasn't failed yet.

[DTro]

Thanks for the replies.

I ended up using plywood and carpet. It turned out pretty good. I'm still not completely satisfied with the way the seats swivlel. The corners are still rubbing. I think I will get some sort of short pedestal.

Here are some before and after pics: