I need to install a small 4x12" section of wood in my floor where I cut out and removed the factory installed subwoofer box. It's located inside the rear bench seat, so nothing fancy needed nor will be stepped on. It will be sealed on the underneath side before installed, then a layer of glass over the joint using some West Sytem I have. Can I use plain plywood? Don't want to buy a full sheet of marine plywood just for this.

Also, I'm installing a thru hull below the waterline on the side for my AC pickup. Do I need to epoxy a peice of wood backer board inside for the nut to tighten up to? If so, what type of wood (hardwood such as walnut?) or can I use a 1/4" thick SS washer larger than the dia as the thru hull fittings nut?

Thanks

yes you can use regular plywood if its outdoor rated. coat all sides and edges with resin and let cure before installing.

you only need the backer board if the fiberglass is to thin to allow the threads to draw up, use plenty of 5200.

Great!

I custom made the thru hull for a special application, so I can cut the threads as deep as needed. I didn't realize the hull side would be a little over 3/4" thick until tonight after drilling the hole, so my 1st thru hull fitting attempt is a little to short to get a shut off valve to seat. Going to make a longer one this week.

Thanks