Seat Base Material - Plywood Alternatives??

[dyost]

Hey guys,

So in typical fashion, a small boat project turned into a potentially major boat project. I bought an 89 Sunsport (Okie Boarder's old boat) in January. After almost 40hrs (a lot of it hard riding) this season, I thought it might be a good idea to tighten all of the tower bolts, including the feet. So I started at the rear left, remove the vinyl panel, find there is a hole cut in the deck (probably for wiring, ballast, or maybe tower install while Okie put the tower on). Perfect!, wrench goes right in and I give the nut on the bottom side of the tower foot about a turn and a half, enough to make me think I should give them all a snug while the tools are out....

So go the front port side. Can't reach the nut, no matter how I try to contort myself into the little storage compartment behind/under the passenger seat. Figure the bow seat base on that side must have to come out, and maybe I'll get lucky and there's an access hole. Go to work on the seat base. 7/16 nut on the side and two screws into the back, except for my stereo amp is on that back wall and the screws used were long enough that they go into the bow seat base, so the amp has to come out.... 3 of 4 screws into the amp removal I find there is a stripped phillips head, on the hardest one to reach. Cordless recip saw, back up and running. Seat base comes out, find there is in fact NOT an access hole, so I cut one in with my jigsaw and tighten the tower foot. Good thing, this one took about 1 3/4 turns.

So here's where the trouble starts......

When I got the first bow seat base out I saw the wood is kinda rotten and moldy. A bunch of little bugs crawling around and I freaked out immediately thinking "TERMITES". Seat base goes to the driveway, wood gets a healthy dose of insect killer as does the bow base under the seats. This first seat is probably structurally ok, I figure at the time I'll kill any bugs, then soak it down with a bleach solution to kill any mold/mildew, clean it up and put it back in....

But my mind has me wondering, if that one is that bad, how do the others look.

Next I go for the nose seat base. PITA to remove cause one of the threaded studs attached to the seat base had come loose and was turning with the nut. Had to remove bow speaker for 2 hand access to hold it with pliers.
This seat base is trashed, completely rotted. I don't even want to put it back in like it is.

Finally, remove the starboard side rear seat base in the bow. This one is in ok shape. It looks like it had some patchwork done to the plywood when the previous, previous owner had the interior vinyl done in what Okie tells me was 2009.

So I'm considering building new seat bases and putting the existing foam and skins on (skins are in great shape, not sure about foam, it seems structurally good but won't know if it's totally rotten till I get them apart).
Anyone have any ideas for alternative materials to plywood? I'm willing to spend a little extra money but not a stupid amount. Any ideas???

Also, if I decide to go the wood route again, what is the best material to use, and how would you seal it up to make sure I can prevent mildew/mold/rot for as long as possible? Any tricks to removing/reinstalling seat skins and foam? Anyone know where to get stainless staples for putting the skins back on?

IMG_6894.jpgIMG_6895.jpgIMG_6897.jpgIMG_6896.jpg

Want to get this going ASAP so can get back to riding.

I've attached some pics for reference. Thanks for the help.