[MHml] Cedar v foam cores

[McRae/Tharp]

Glenn,
I was hoping a more experienced person would give a concise answer. 
Since to date no one has I will  tell you how I figure it and maybe some 
one will set me straight.
Cedar weighs about 23 lbs per CF and foam 5 to 5.5 lbs per CF. For 
reference Balsa is 10.6 lbs per CF.   With cedar you can down size the 
laminates.For the 32 Ian F. calls for 18 oz.BD outside for foam and 6oz 
uni for cedar. !2 and 4 for the inside. So there is a savings of weight  
on the glass and epoxy for the cedar.
Roughly I  figured for a F32 about 40 sheets  4x8' foam for the hulls. I 
am leaving out the bulkheads for now.
Cedar would weigh        40 sheets x 32 sq. ft x  1/2"/12"/Ft   x 23#/CF 
   = 1686#
                       epoxy + glass        about 213 #           for a 
total of   1900#

Foam                      40 x 32 x    1/2" / 12  x 5.5  + 365 #
                        Epoxy + glass    about   640#          For a 
total  of1005 lbs.

Depending on what is used for bulkheads the weight difference will vary.

Rod T
              

>
>Anyone care to comment on the relative weights produced by use of epoxy & 
>cedar strip vs foam core in multihull construction?
>
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