Material to fabricate sub mount out of

[Asmodeus2112]

If this wasn't a marine install, I'd use plywood for this. What's the equivalent of plywood for a marine application? I'm mounting a bazooka sub, and just need a few .75" x 24" x 1" stips that I can screw down to the floor.

[Earmark Marine]

MDO or Medex are solvent-based adhesive constructed exterior-grade materials often used for outdoor signage that last years in the elements. It still helps to seal the material with a polyester resin, exopy resin or a polyurethane bed liner . And, I would elevate ANY wood-based product off the sole with a 1/2" thick polymer product like PVC, HDPE, ABS, KingStarboard, etc. Actually if you use one of these polymers as a bottom pad then you can use a standard birch plywood stacked on top.

David

[JTech]

Go find a scrap piece of Composite decking (Trex Deck, etc.) at a local lumber yard or deck company. Works great!

[skibreeze]

Azek is a brand of pvc trim that will work.

[TallRedRider]

Go find a scrap piece of Composite decking (Trex Deck, etc.) at a local lumber yard or deck company. Works great!

That is what I used on my new box.

The previous 'professional' installers didn't use any kind of feet under the sub and at least it lasted several years before the water exposure, mold and mildew softened the box and it was starting to fall apart.