Marine Vs Exterior Plywood
D. Marier
Marine Vs Exterior Plywood
In Canada the manufacturers do not make marine plywood they produced
exterior plywood. According to the Canadian Manufacturers there are
no differences. The glue used is waterproof for exterior, interior or
marine plywood.
So if we want plywood labeled “Marine” we have to get it from the
Netherlands and paid big bucks for it.
In theory the Canadian Manufacturers claimed no difference. In
practice, a boat build with marine plywood will outlast one made with
exterior plywood. So what is the differences, the Dutch have a 20
year's warranty ( for what its worth) and they states that the glue is
not the only thing. After gluing the Marine plywood is soaked in
chemical baths and cured according to manufacturing procedures??
Well is this true? I do not know and I would appreciate any comments
before spending the extra money..
Denis Marier
mar...@mi.net
Rothesay, New Brunswick
Canada
Bryon Kass
The British standard for marine plywood is a boil test. I assume they
cook it and rate it for delamination or a time factor. Brunzeel is
one that passes, there are others. The only difference between marine
fir ply and exterior is the quality grading. The exterior usually has
air voids inside the laminate which on a boat could be very bad. It all
depends on the application. If you can find an ext ply with no voids,
many more plys than standard, I would use it on the bulkheads and decks,
but not the hull. There are plenty of US dealers in marine grade so
you do not have to go to Europe. Check with Boulter Plywood in Somerville,
MA. They have some excellent species of marine grade ply for all I
have ever needed.
Bryon Kass
webmaster and
Custom Design
150 Mechanic St.
Foxboro, MA 02035
508-543-9068 or fax 508-543-5127
in THE ENGINE ROOM http://www.ici.net/customers/cusdn
Kurt Gardner
Marine plywood is no longer available for one reason. It is BS, no matter
what type of plywood you use you still have to use a chemical sealer to
keep the wood from rotting, better known as resin. Do not spend the extra
bucks for so called marine plywood it's not worth it.
D. Marier <mar...@mi.net> wrote in article <54eam1$h...@scratchy.mis.ca>...
Lawrence
How about pressure treated plywood, lowes etc have that. Sealing it is
certainly a good option but I know on my boat the deck plywood is not
sealed.
Bill Derby
BCX out of Southern Yellow Pine (SYP) this is still heavy, but will be
an excellent plywood. I made my sons kayak out of 1/4" and I am making
me a sailing dingy out of 3/8". I have a sheet of 1/2 that has been
laying on my porch for 4 years with no paint etc and is still laminated,
no checking.
Bill Derby
Dave Anker
I have used pressure treated plywood for boat repair and have been
very pleased with it. It's true that it tends to be heavier than
conventional exterior plywood, but I left mine to dry in the sun for
3 or 4 summer days before I used it. That lightened it
considerably. I used the wood to rebuild the trasom of a fiberglass
boat. That was about 7 years ago and the transom is still like it
was the day that I finished the project.
Regards,
Dave
Ross Fleming
On 31 Oct 1996 05:25:47 -0800, Lawrence wrote:
>How about pressure treated plywood, lowes etc have that. Sealing it is
>certainly a good option but I know on my boat the deck plywood is not
>sealed.
>>
>>Marine plywood is no longer available for one reason. It is BS, no matter
>>what type of plywood you use you still have to use a chemical sealer to
>>keep the wood from rotting, better known as resin. Do not spend the extra
>>bucks for so called marine plywood it's not worth it.
One of your biggest concerns should be getting good quality plywood.
These days it is difficult to find plywood that doesn't have voids or
large knots in it. I would suggest that you consider the structural
properties of the wood and plan on sealing whatever you get. Look at
the diffearnt thickness of the laminate and look for voids.
--------------------------------------------------------------------
Ross Fleming O-
Seattle, Wa.
ross...@u.washington.edu or ross...@serv.net
skiff...@aol.com
Marine plywood has all solid wood veneers that are the same quality. It
would be the best choice for boats especially below the waterline. AC
exterior is the next best. I have used a lot of AC exterior and it has
one good side and one side with cosmetic problems, voids and the like.
These have to be filled with whatever goop you are to be using. The
choice is personal and depends on the application. Pretty stuff that is
to be stained and varnished, one may want a nice veneer, mahogany veneer,
or such. I have been sheathing my boats with fiberglass cloth saturated
with either expoxy resin or polyester resin. Prior to this, I saturate
the plywood with a host of chemicals, in order, wood preservative, plywood
sealer, fiberglass/expoxy, marine primer, and paint. I think if one takes
the proper precautions AC exterior is OK. It's still likely to check a
little after years of service.
jm...@aol.com
In article <19961109142...@ladder01.news.aol.com>,
skiff...@aol.com writes:
>Marine plywood has all solid wood veneers that are the same quality. It
>would be the best choice for boats especially below the waterline. AC
>exterior is the next best.
The never ending discussion about marine plywood or exterior should take
place in rec.boats.building.
The confusion in this discussion comes from the fact that the plywood in
question can be used in different ways. In traditional plywood boat
building, the plywood is used differently than in epoxy-fiberglass-plywood
composite boat building. Stitch and Glue, at least in my designs, is a
composite boat building method in which the plywood is the core of the
composite. We use some of the properties of the plywood in the structure
but not as much as in traditional plywood boat building.
In composite boat building, we don't care about resistance to humidity
because the water never gets to the plywood. We don't care either about
surface aspect because it's fibreglassed or at least epoxy coated all
over. We like a plywood with consistent mechanical qualities, no voids but
that can be found in other types than marine plywood.
We choose plywood as a core because it's easily available, easy to work
with and inexpensive but we could as well build these boats with foam
panels and a slightly different lamination schedule.
The plywood that we use is named Marine Tech from Plum Creek. We buy ours
from McEwen Lumber in Stuart Florida but any good lumber yard should be
able to supply it. For the technicians, this plywood quality is defined in
the Industrial Panel Guide as ICI #9344. It has almost no voids in the
core (same as US Fir marine plywood) and same glue.
For more information and local availability call Plum Creek at
(406)892-6336. Be aware that this plywood was designed for professional
boat manufacturers, mostly to use for stringers, bulkheads, floors or
transom inserts and that they don't seem too enthusiast to sell to
amateurs.
We pay $ 14.00 for the cheapest 1/4",3 plies, $23.40 for 1/2" 5 ply
compared to $ 41.00 for marine fir.
We switched from Lauan because in Lauan, the outer skins were very thin
and the core thick and "soft". In Marine Tech, all layers have the same
thickness, same type of wood.
There are other companies manufacturing "boat building plywood", one day I
will list them in a suppliers file at our web site but for the time being,
start with a search for Marine Tech at your local lumber yard.
Jacques Mertens
Boat Plans Online: http://www.bateau.com