Is it possible to use 'exterior' grade plywoods which are much cheaper than
marine plywoods? You could use a glass resin or just a strong yacht varnish
to weather it.
I'm building a 12 ft sailing boat. I used white deal to build the frames and
a bit of parana pine for the keel (which I may have to remove because it
might swell).
But using 6 sheets of 'marine' plywood will break the bank.
For six sheets of 8x4 ft plywood I will fork out up to 600Euro (which is
close to 600 US dollars).
'Exterior' or some lesser grade might be half the price or even less and
might work with a few extra coats of paint!!
Will it work??

MT. Ireland

mctimlin asks:

Is it possible to use 'exterior' grade plywoods which are much cheaper than
marine plywoods?

The literal answer would be "Yes", but.....
It all depends on how long you want to keep the boat for.
Marine ply exists for a very good reason. I would recommend a google search on
a thread from a few weeks ago that rambled on forever about just this topic.

Steve
Stephen C. Baker - Yacht Designer
http://members.aol.com/SailDesign/pr...cbweb/home.htm

yes. you have to look for good sheets with no or few gaps in the in the
interior plys. they usually show up along the edge. and with few
imperfections in the face plays. good sheets can be hard to find.

if you are using douglas fir exterior plywood which is what we have here
in Canada (or marine grade for that matter) it expands and contracts with
changes in temperature and humidiy, particularly direct sunlight, and the
surface cracks ("checks"). you either live with it or you put on 2-3
layers of resin soaked fiberglass to prevent the checking.

if you can get exterior grade meranti which seems to be what amateurs use
for small boats in the USA, it would be better than fir.


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