What kind of plywood for in boat use?

[Bruce]

I am going to fabricate plywood walls between the under seat storage area and the engine compartment storage.

What kind of plywood would you use and how thick? My primary goal is sound reduction. I will be applying a dynamat type product and carpet to the plywood.

The materials that are readily available are 1/2" Pine Pressure Treated Plywood, AdvanTech 23/32 OSB Subfloor (OSB guaranteed for 300 days of water exposure) or 1/2 Birch Plywood.

I have worked with all three types of wood and am leaning toward the AdvanTech. It is a very dense OSB product and has worked well as the subfloors in my home. I plan to call around and see if I can find 1/2 Advantech.

Thanks for your advice.

 

[BigN8]

I would use pine but put a couple coats of polyurethane on it

 

[BigN8]

http://m.homedepot.com/p/Unbranded-3-4-In-4-Ft-x-8-Ft-AB-Marine-Plywood-726540/202084532

 

[Murf'n'surf]

Since your application is not structural any if the three will do ok. Personally I hate OSB and stay away from it because of its water absorbing nature. Encapsulate your boards with a quick coat if epoxy and you won't have to worry.

 

[txav8r]

Bruce, the most permanent and best is what has the least amount of pores within it. That will be birch plywood. Baltic birch specifically. It is filled as it is laid up so it won't contain voids. Voids will radiate sound, so if your after the best structure, sound resistance, or rot resistance, you want to eliminate voids. If you resin coat it, it will be waterproof enough. Like were discussing in another thread, any penetrations you make through the resin protection after construction are possible rot areas...but only if water gets into them constantly, like the cleanout tray hatch hinge screws. If it can take that kind of abuse for years, it will work in your compartments. What are you after specifically in your design? Sound separation or compartments? @Bruce

 

[Seadeals]

I would stay away from the pressure treated wood due to the chemicals. Marine AB has all defects (voids) filled, whereas cheaper plywood will have voids from where knots were removed in the middle of the sandwiched layers. Since it is not really structural, you should not need the extra strength and weight of marine grade plywood, plus you are covering it all up with carpet.

 

[Bruce]

@txav8r, I removed the side walls in the engine area to install the behind the cushion speakers on the swim deck. I decided to reclaim that space and use it. I moved the battery into that area and am adding a second further back. I will have a tool storage area behind the batteries on the port side. I am adding a 15 gallon tank for shower water on the starboard side with grill storage above that.

Removing the sidewalls allowed additional sound to come forward under the rear seats. I am hopeful that installing a solid wall with sound deadening material will make the boat quieter than factory.

 

[txav8r]

Yamaha uses basic substrates Baltic birch would be a vast improvement.

 

[cybuch]

Yamaha uses basic substrates Baltic birch would be a vast improvement.

+1 on Baltic! Thats what I built my sub enclosures out of.

 

[KXCam22]

My favorite non-marine plywood is called Okume. It is the closes to marine grade and not that expensive. OSB and MDF are definitely not for a boat. The best product to coat wood for marine use is fiberglass resin. The second best is marine varnish. I have used marine varnish a few time and got great results and longevity out of it. Cam.

 

[Glassman]

Take a look at King Starlite XL:

http://www.kingplastic.com/wp-content/uploads/King-StarLite-XL-Literature1.pdf

http://www.jamestowndistributors.com/userportal/show_product.do?pid=13880

Nothing to treat, easy to work with. Yeah, a little pricey, but it's only money.