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Marine Grade or Treated Plywood??

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TODD DAVIS

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Sep 28, 2002, 12:48:50 PM9/28/02
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My fall project will be replacing all the plywood backing on all
cushions in my boat. I own a 20ft 82' Webbcraft openbow, and sun
pad. To say the least this boat has alot plywood to replace. All
the cushions are in great shape, no sun fade or rips.

Here is my question. Should I use treated plywood, or Marine Grade
plywood?? I was told treated plywood will hold up to water for 5
years. Marine grade will hold up much longer. I checked into the
price of Marine Grade plywood!! Wow, not cheap....

I always cover my boat when not in use, and always let it dry uncovered
after use.

What are your thoughts????

Todd

Calif Bill

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Sep 28, 2002, 2:16:47 PM9/28/02
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For non-structural plywood, go with other than Marine grade ply. Marine
Grade, means there are no voids inside the sheet, which both can collect
water and if used in a transom, means there is a weak point in the plywood.
My 1991 boat has treated ply floorboards (this is an up level aluminum boat)
and they are covered with sheet vinyl flooring (available from West Marine,
etc). The flooring has been fine for all these years.
Bill

"TODD DAVIS" <TWD...@webtv.net> wrote in message
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Ed Strobel

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Sep 28, 2002, 3:57:01 PM9/28/02
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If you cut it, let it dry (Most wood is still quite moist when you buy it)
and paint it, most any exterior grade will work. I did that with my
covering boards 7 years ago and no problems. Another clue... use monel
staples and CHECK THEM with a magnet. I once bought a pack that someone
most have swapped with standard ones and returned to the store and they of
course rusted in about a month.

"Calif Bill" <bmckee...@ix.netcom.com> wrote in message
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Gould 0738

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Sep 28, 2002, 6:41:48 PM9/28/02
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Consider a synthetic, non wood product for your seats. No more rot. Ever.

Dan Krueger

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Sep 28, 2002, 7:39:26 PM9/28/02
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He already said the price of marine grade plywood was restrictive.
Starboard is going to triple that!

http://www.kingstarboard.com/

Dan

Gould 0738

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Sep 28, 2002, 8:16:48 PM9/28/02
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>He already said the price of marine grade plywood was restrictive.
> Starboard is going to triple that!
>
>

Yes, if it's just a price consideration you are correct.


Megabite

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Sep 28, 2002, 10:05:38 PM9/28/02
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I use M.D.O. (Medium Density Overlay) or "Sign Board" as it is often
referred to. It also is called "Creezon Board" It has a Resin Impregnated
And laminated finish. The entire interior, wherever plywood was called for,
on my Sea Ray was built with the stuff, by the factory. Easy to recognize
with its perfectly smooth brown paper looking finish (Actually Resin) 48" x
96" x 3/4" about $45.00 - $55.00 a sheet depending upon the usual supply and
demand marjet pressures.

"TODD DAVIS" <TWD...@webtv.net> wrote in message
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Megabite

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Sep 28, 2002, 10:07:28 PM9/28/02
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You mean like Bayliners Harry?...................:)
"Harry Krause" <hkr...@hotmail.com> wrote in message
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> How about outdoor ply with a few coats of epoxy? Including any holes
> through which cushion fasteners are punched?
>


LaBomba182

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Sep 28, 2002, 10:21:41 PM9/28/02
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>Subject: Re: Marine Grade or Treated Plywood??
>From: Dan Krueger

>He already said the price of marine grade plywood was restrictive.
> Starboard is going to triple that!
>
>http://www.kingstarboard.com/
>
>

Yes, but with Starboard there's no sealing, priming and painting.

Capt. Bill

Edward Greeley

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Sep 29, 2002, 1:32:26 AM9/29/02
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If by "treated" you mean the greenish-looking, pressure treated stuff,
that material is no good unless it is fastened to some sort of framing
material to keep it from warping. In my experience, if 1/2 inch, or even
3/4 inch ply is used as cushion backings, it will soon be warped this
way and that so it will not sit flat on the surface it is supposed to
rest on. If the cushions can be securely fastened to something rigid,
the treated stuff would be OK, but that is not normally the case with
cushions. Marine plywood will have more layers of veneer for a given
thickness and is, therefore, much more stable although it must be well
sealed for stability and longevity. Common "exterior grade" fir, as
available nowdays, is semi-acceptable from a stability standpoint if
properly sealed by the user, but is not "your Daddy's plywood" of 30 or
40 years ago. Don't even consider the lousy "exterior grade" pine
plywood - it is not even good to build fires with. BTW, all the
"treated" (pressure treated) plywood I have seen is pine, not fir. I
stand to be corrected on that.

As I said - my experience, FWIW.

Ed Greeley

David

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Sep 30, 2002, 1:21:46 AM9/30/02
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Here is my two cents worth:
Marine plywood is only Doug Fir lay up, marine glue. "A" face, "B" inner and
back plies and minimal voids on the inner cores. It has no treatment at
all.It is a nice piece of wood ( thus the price) mostly an appearance
product.
Regular treated plywood is just plywood treated with CCA, and typically
treated to a .60 ( moisture/ground contact) it is not the prettiest nor
flattest
Third choice and middle of the road is a treated boat panel. Typically that
used all Doug Fir lay-up, marine glue. "B" or "C" face with "C" inner and
back with minimal voids and treated with CCA. it is only treated to a .40
and can not come in contact with water or the dirt. The boat panels I have
seen called a "C" face and the knots were about 1/8" acrossand priced with
reg. treated plywood. You might end up going to a plywood distributor for
it. The name I have seen is"XL Select" and I forget the manufacture, but
that doesn't matter as the APA calls out the specs.
Good luck
David
Edward Greeley <etgr...@worldnet.att.net> wrote in message
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TODD DAVIS

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Oct 2, 2002, 8:52:57 PM10/2/02
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I would like to thank everyone for their input on this subject. I
know I have learned a few things on this subject. I hope others have
also.

Todd

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