Swap wood panel in upholstery

[Lpgc]

My boat is a 1996 Four Winns Sundower.

The wood that forms the base of the upholstered panel that runs the width of the boat between rear seats and swim platform (the upward facing trim you'd climb over to get into the boat from the swim platform, it's hinged to the boat to allow access to the battery switch and rear of the engine) is rotten but the vinyl upholstery and sponge are in good condition. I want to keep the vinyl and sponge/foam but replace the rotten wood. I have already removed this panel from the boat and stripped it down without damaging the vinyl or sponge.

I think I'll need a piece of 3/4" x 80" x 33" marine ply to replace the rotten wood with, use the old wood as a template and jigsaw to the same rounded shape. I don't know if I should treat the new plywood after getting it to the correct shape? The foam was in some kind of clear plastic bag/wrap which was damaged during removal, what sort of plastic should I wrap the foam in? Should the foam be completely wrapped in plastic or no plastic where it contacts the new wood below it? Should the foam or plastic be glued to the wood?

 

[Chris1956]

Normally the wood in seats is 1/2 plywood. However, if yours is thicker, replace with the same stuff.

I would use pressure treated plywood that has had a chance to dry well. Apply a couple of coats of oil-based varnish or polyester resin to seal it and use stainless steel staples to reattach the vinyl.

PT plywood will not rot as fast as untreated plywood, and stainless steel staples will not rust out in a year or so, like galvanized ones.

Often a 3/4" hole is drilled in the center of the plywood to allow any water to drain. That likely provides some small benefit.

 

[jbcurt00]

Monel staples are an even better choice over stainless.