[Rhodes22-list] Reply on Motor Mount part 2

[Tootle]

Folks,

	There are many kinds of plywood.  Marine plywood is usually made with
layers at cross grain and with water resistant glues.  I suspect the truss
plywood is not made the same.  I am not going to use it again, that simple.

	You all are trying to reinvent the wheel.  I think that Commodore Spitzer
discovered the issue 20 to 30 years ago and went to plastic as backing for
the motor mount.  Captain Rummy’s stainless steel backing plate adds
strength and rigidity to the system.

	Art’s concern about backing on the inside of the transom again has been
addressed by Commodore Spitzer.  Current boats and recycled boats have
either wood or marine plywood backing.  Behind the tiller the wood is
usually glassed over.  Glassing over what ever is used seals the material
and more importantly adds strength to the system.  In glass work strength is
achieved by layering and increased by adding space between layers, but not
empty space.  Rigidity is achieved by adding space between layers, but not
completely empty space.  

	Art, if you will examine your 1984 project boat, I expect you will find
plywood glassed over as backing for the inside of the rudder bolts.  That
may not have been the case on your older craft.  That was part of Stan’s
learning curve. 

	Now if you did not run off Roger, we could have a scientific explanation of 
the materials and material strength analysis thereof.

Ed K
Greenville, SC, USA
Addendum:
“The chance for mistakes is about equal to the number of crew squared.” Ted
Turner



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