"Marine-Grade" Baltic birch plywood

toyL

Member
I know what "plywood" is. I understand what is meant by the term "Baltic birch". Does anyone here know what "Marine grade" means?
Thanks.
 
see:

Is Marine Grade Plywood the same as Baltic Birch Plywood? - Woodworking Stack Exchange

note these bits:

"Marine plywood had no voids. Other types of plywood often have voids in the inner plys. This is why marine plywood is so expensive. I assume baltic birch has voids.

"In marine plywood these voids have been filled with inlays to insure strength and reliable performance under the stresses that a boat is subject to.

"It's my understanding that the glue is the same for all plywood these days. It did not used to be. Other that the absence of voids, I don't think marine plywood is any more resistant to water than other plywood."
 
As [MENTION=45599]gecko zzed[/MENTION] posted, the key is the lack of voids. Very important for boat building, and maybe worth considering if you're building something like a Voice Of The Theater type enclosure that's going to be used at deafening levels, and you don't want the weight of MDF. Otherwise, it's overkill for almost anything.

I did use some for some floor monitors I built back in 1975, though, and they're still in use :).
 
I believe you get no-void ply by simply selecting A-A or A-B grades.
Both are pricey furniture stuff, but it seems like there's always an extra premium placed on "marine grade".

Marine grade is supposed to be water-resistant (none of it is really waterproof) but like Gekko said, it's probably all about the same these days. None of mine have ever been in the rain for more than a few minutes and never the bare wood.

Voids are not thing! Yes, legend has it you'll get 'buzzing', but I've never seen it happen in dozens of homebrew projects with every kind of questionable grade there was -- right down to CD grade concrete form, crating crap. Can't say it won't ever happen and never has happened, but it's been the subject of considerable more stories than experience.

I think it's a 'selling point' for speaker builders. And maybe they've seen it happen. Or maybe they just wanna sell speakers. Dunno.
 
For other than "lead" guitar speakers the best material for speakers in most ways is MDF. No voids if that is a worry and the material is denser than ply and that helps acoustically.

Ply is prefered for guitar speakers because it is stronger and has much greater impact resistance and git cabs tend to get a hard time. There is also a school of thought that the denser, less resonant nature of MDF "robs" guitar cabs of a desirable tone?
Can o worms that one!

Dave.
 
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