So I bought this marine plywood and....

[Peggy Babcock]

So, I bought this marine plywood, doug fir, AB in 2 widths-- 3/8 and
1/2 (they are stamped marine grade on the edge). The 3/8 sheets are
all EXACTLY 3/8. The 1/2 inch is 1/16 shy. This seems pretty short of
8/16.

Well... based on what I'm using it for I could live with that I guess.

Then I look at the surfaces. The 3/8 is beautiful. A few plugs here
and there, and it's difficult to tell the A side from the B side.

The 1/2 is a different story. More plugs, and now I'm seeing wood
putty filling what I guess are dings and imperfections (they are from
1/2 inch to 1 inch in size). I see these on both sides and I can't
tell which side is the A side.

I'm still deciding whether to take it back to the yard and wait for
some more pieces or just deal with it and move on with my life.

Question is... What's with the wood putty? Is that normal on marine
plywood? Is it usual to see it on the A side?

[Glenn Ashmore]

American made fir plywoods of nominal 1/2" and thicker are usually about
1/32" under. An "A" face marine ply can have a few footballs but should
not have any putty filler. There should be at least 2 more plys on marine
grade over 1/4" than normal exterior ply. Theoretically there should be
no voids but I have found a few recently.

I have gotten so discouraged about US made marine that I don't use it any
more. Imported red maranti is so much better made with such high quality
faces and often twice as many plys. The price of 1/2" meranti from Noah's
is only about $5 more delivered than my local lumber yard can sell me
American fir marine. For me, American made marine plywood is just not
even in the competition any more unless you are building a dock or
something.

Peggy Babcock wrote:

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.mindspring.com/~gashmore

[Migchelsen]

And if you are going to fiberglass it, you are better off with Philippine
mahogany that costs you less than 25 percent of what you pay now. Been there,
done that. Barend

[Gary Zwissler]

Take your 1/2" back. You paid for marine ply, and got something else. The
yard I buy from is a hardwood and fine wood distributor. All american
plywood standards are set by industry groups and the manufacturers
voluntarily adhere to the standards - including stamping the sheets as to
their grade. My supplier knows the standards and buys from manufacturers
who don't fudge the rules (and it costs me a couple bucks more a sheet).
There are too many manufacturers that fudge the rules, so the reputation
that US plywood is gaining is well deserved (see Glen's post). If you can
find a supplier that will buy and inspect the plywood you will be light
years ahead (ask your supplier what distinguishes plywood grades, then ask
how they check, then ask who they buy the stuff from - if they can't or
won't answer be dubious. I've even talked to the purchasing agent after
explaining that I was building a boat and people's lives are on the line).
Interestingly I've found the 1/2" and 3/4" high-quality doug fir marine ply
I've bought has been EXACTLY 1/2 and 3/4". I've found that if marine ply is
the usual 1/32" under, it will most likely fall short in other aspects as
well, such as knots, voids, and/or putty. It sounds to me like you got 1/2"
that is cheaply made, coming closer to A/B or A/C exterior. Take the junk
back. (I once returned forty sheets of plywood to another distributor
because of similar problems. Also, if you buy special orders from home
warehouses you will have problems - guaranteed).

Gary
www.missrebecca.com

Peggy Babcock <peggybabcock@*nospam*bigfoot.com> wrote in message
news:3a6a3a6c...@news.nycap.rr.com...

[Pat Ford]

Except that, I far as I know, there is NO Philipine mahogany plywood
that is certified waterproof.

[Stephen King]

Isn't this the mahogany that also goes by the name Okoume?

Steve King

[Glenn Ashmore]

Stephen King wrote:

> Isn't this the mahogany that also goes by the name Okoume?

No. Marine plywood made from luan (Philippine mahogany) is called Meranti. Okoume
comes from Gabon in Africa and is about 20% lighter than luan/meranti.

It is a marketing thing because people don't like paying that kind of price for
luan. Like for years "Finnish" birch actually came from the USSR. It was a higher
grade than anything made in the US but cabinet makers didn't believe that Russians
could make anything good but Stoly.

While marine meranti and lumberyard luan plywood are made from the same wood
species, they are as different as night and day. Marine meranti uses better
veneers, thinner plys and waterproof glue. Cabinet grade luan that comes from Lowes
and the Home Despot is used for backing and drawer bottoms. It will fall apart if
any water gets through the glass at all.

[Migchelsen]

Even if it is not, no wood is. The glue is waterproof. But it is only used as
a"coathanger" for the fiberglass., Barend

[Migchelsen]

Okoume is a high quality (African?) marine ply. Not the crap that they sold to
our man. It costs also high quality dollars. Marine ply is excellent in only
two cases: If you have money to splurge, and if you are going to blank varnis
only. The high quality wood resists deep penetration of the epoxy. For good
penetration you need lower quality softwood with an open grain. I built a scow.
Sides were the best Bruynzeel Marine ply money could buy. Bottom was cheap,
open grained Douglass fir ply. Taped the seams. After a couple of years, the
fiberglass tape came off. NOT on the fir, but on the high quality side panels.
Been there, done that, Barend

[Peggy Babcock]

Well, I decided to keep the substandard 1/2" plywood. Thanks for all
your input. sounds like I got some of the crappy stuff that others
have found. The reason I will keep it is because in most cases it will
be encased in epoxy/fiberglass and will see no bending. I'll be using
it doubled up for the rudder, and centerboard, and in single sheets
for the CB trunk sides. The bottom of the boat is the place that I'm
most concerned with and I plan to fiberglass both inside and out
there.

I figure it's my first boat, it's not a piano (that's my mantra!) so
I'll learn a bunch along the way and have more fun when I'm finally
out there sailnig.

I'm building GlenL's Alpha II... 18 foot sailing dory and loving every
minute of it!

[David Flew]

I'd at leat do some sort of check to make sure that it is crappy waterproof
ply, not a mike-up with something else. Others can advise you on the
appropriate test, but I recall a reference to 30 minutes in boiling water
without delamination. Only need a small slice off the edge, and it would be
a shame to put in the effort on a non-waterproof material.
David

Peggy Babcock <peggybabcock@*nospam*bigfoot.com> wrote in message

news:3a6cbe6...@news.nycap.rr.com...

[sfk...@mindspring.com]

David's advice is right on target. I was recently in the same situation as
you except after further investigation the manager of the plywood department
found that someone had switched the labels on the plywood and had walked out
of the store with two sheets of marine grade that should have been BC
exterior. I had 4 sheets and 2 of them were the same description as you gave
and 2 were "obviously" of a better grade and thicker. I discovered this
several weeks after it happened but the yard made good by trading it back
for what I had paid for.
Best regards,
Frank

[Peggy Babcock]

Both sets (good and bad) of plywood have identical "marine grade"
stamps on the edge. They also both a nice tight 5-ply. I've already
cut them up into shapes and have found no voids. I'll boil some
tonight and report back....