Replacing plywood bottoms of vintage seat cushions

We've begun what looks to be a rather arduous process of repairing the seats in my 1960 Crestliner Flying Crest boat. The seats had all been rebuilt almost from scratch about 20 years ago, I'm guessing. They used treated plywood on the bottom of the seat cushions with no additional sealant applied, then wrapped the vinyl upholstery over the edge and stapled it there. The plywood has gotten rotten and moldy over the years although, surprisingly, most of the upholstery and foam is quite salvageable.

We're taking the upholstery covers off then cleaning and disinfecting those and the foam. We should be able to reuse just about all of it. My question has to do with replacing the plywood in such a way that this won't happen again anytime soon. I'm sure that some folks will recommend that I use marine ply. I'll see if I can afford it, but I'll certainly use a good grade of plywood with few voids.

But how should I seal it? I'm considering giving it 2 or 3 coats of some decent marine varnish top and bottom before reassembling, although I suspect that even a topside paint would do the trick. I'd like to stay away from real high-priced products. Remember that these seats are far from perfect to begin with.

Any reports about similar projects would be appreciated. Thanks!

Re: Replacing plywood bottoms of vintage seat cushions

Just some regular exterior plywood with several coats of a good varnish.....The ones you have now lasted 20 years with nothing....

Coating the wood with expoxy would be better, (and some will argue) but I've done plenty of seats just a good varnish and had no problems at all.

Oh and the just rolled over and stapled is very much the norm.....glad to hear your coverings are still in good shape.

Re: Replacing plywood bottoms of vintage seat cushions

Thanks for that info, Cadwelder!

Re: Replacing plywood bottoms of vintage seat cushions

Like you said, ideally marine ply is best, however for this application I don't think it necessary. I would use a good hardwood ply (NOT treated) and seal it in epoxy (3-4 coats) getting the end grains really well (end grains are the most important part to seal). In my opinion, I guess if you're going through the work of re-doing the seats, for under $120 you can do it right by using epoxy. As far as using staples, as long as the staples are stainless, that's how it's done. Hope this helps!

Re: Replacing plywood bottoms of vintage seat cushions

Thanks, BWT. I don't doubt that you're right about epoxy being a better product. Cash is just so tight tight right now, and I've got a long list of repairs before this thing is "sea-worthy." I bought marine varnish yesterday and actually got lucky and found a nice sheet of better grade 1/2" exterior ply finished on one side for $20! Realistically, by the time the varnished plywood fails, I think it will be time for new seats again.

Also, I do not receive notifications to threads that I'm subscribed to. I've contacted the list admin but got no response. Does anyone else have this problem?

Re: Replacing plywood bottoms of vintage seat cushions

Yeah, the Notification thing has not worked since the NEW IMPROVED forum format came out. I would recommend this. Buy some of the 10 Minute epoxy that comes in the Syringe Tubes @ Lowe's Use it JUST for the edges of the wood That is the MOST important area where moisture attacks the wood. If you get them coated well, then the varnish will protect the rest and your Grandkids will be enjoying those seats when they are your age. I just rebuilt and reupholstered some fishing seats for my boat and that's what I did and it worked great!!!!

Re: Replacing plywood bottoms of vintage seat cushions

That's an interesting idea. You're talking about the two tube products that you stir after extruding?

Re: Replacing plywood bottoms of vintage seat cushions

Yeppir, Like this...

Comes in two small bottles, Sets up in 5 minutes. Easy to mix and I used acid brushes to apply. Worked GREAT!