Marine Plywood?
All materials used in this tutorial can be found at boatbuildercentral.com
Boat Plans are available at bateau.com
Boat Building Plywood
Currently (2007), the situation is as follows:
If you did spend some time reading boat building magazines or rec.boats.building
on the Usenet, you probably witnessed some discussions or arguments
about the type of plywood that should be used to build a good boat.
We plan to expand on this subject soon and present a much larger
file about this but in a nutshell, you do not need marine plywood
to build a good boat if you use epoxy.
Epoxy resin will completely encapsulate your plywood and protect
it from the water. No need for special glues or rare species of
wood: the water will never get to the plywood.
The most important components in our stitch and glue boats are
the epoxy resin and fiberglass, not the plywood.
You can built most of our small boats with cheap plywood and end
up with a good boat if you use the proper resins and glass but this
is not true the other way around. If you use expensive marine plywood
and bad resin, you may end up with a weak structure that will not
last very long. While we specify marine plywood in some of our larger
boats mostly for its mechanical properties, the most important components
are still the resin and fiberglass.
The controversy about plywood is based on confusion and lack of
understanding of new boat building techniques and materials. Stitch
and Glue, as we specify it, is not wooden boat building.
It is a composite boat building technique that uses plywood panels.
In some of our boats, the plywood is used as a core sandwiched between
layers of fiberglass. The structure of our boats and the way we
protect them from the elements is much closer to fiberglass boat
building than to wooden boat building. The structural engineering
of our designs is similar to composite boat building (fiberglass
etc.) and has very little to do with traditional wooden boat building.
For most of our small boats, we recommend the use of inexpensive
Lauan plywood. Larger ones use good exterior plywood with no voids
or boat building plywood (an APA specification) or in some cases,
marine plywood.
Yes, there have been problems with plywood parts encapsulated in
polyester resin but not with epoxy. 20 years ago,
boat builders did not understand that polyester is not 100% waterproof
and this resulted in rotten plywood transoms and floors and also
in hull blisters. This problem has been solved with epoxy resins:
we exclusively specify epoxy resins, never use polyester.
Trust our 25 years of design and engineering experience: we specify
inexpensive plywood for some of our commercial designs since 10
years and out of thousands of boats built, there was never a failure.
Use the plywoods that we specify with the proper resins and fiberglass:
epoxy resins that are formulated for boat building and directional
glass that participates in the structure. These materials are always
available from us as mail order kits, at a discounted price, if
you can not find them locally.
Learn more about plywood: See our page about plywood classifications
as per the APA. See our resin-fiberglass basic tutorial for more
information about these materials.
If you did not find the answer to your question, please use our
message board and
we will respond within a few hours.
Or explore the HowTo files at our technical support web site bateau2.com
