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Re: Structural engineering question

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  • John Howard
    Cal, You are correct about the weight differences. White and sugar pine are about 25-27 lbs/Cu.Ft, Cedar 22 Lbs/Cu.Ft, Redwood 28 Lbs/Cu.Ft and Mahogany and
    Message 1 of 15 , Dec 23, 2004
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      Cal,
      You are correct about the weight differences. White and sugar pine
      are about 25-27 lbs/Cu.Ft, Cedar 22 Lbs/Cu.Ft, Redwood 28 Lbs/Cu.Ft
      and Mahogany and Shortleaf (yellow?) Pine run about 36 Lbs/Cu.Ft.
      Depending on the amount of mahogany the weight gain over just Cedar
      would be small if the mahogany were decorative pieces/strips. More
      mahogany = more weight. A large percentage of mahogany would need to
      be used to make a major difference. White pine has been used by some
      builders to strip the entire bottom below the waterline for
      design/contrast and as an aide in spotting a capsized craft without
      adding any weight.

      Cedar, Redwood, White Pine and Mahogany are all commonly used in
      building strippers, Cedar as the base wood and the others mostly for
      adding contrast and design to the individual boat. Other woods are
      also used for decoration. Rosewood, Ebony, Holly and dyed woods are
      usually used as an accent, sometimes inlayed, sometimes part of the
      structure, but almost always in small amounts. Take a look at other
      web sites for ideas on how the different spiecies are used for
      design and decoration.

      The other consideration on weight is the application of the epoxy,
      how many layers and the weight of the fiberglass cloth. Adding the
      extra layer on the bottom for abrasion will make a difference as
      will 4 oz cloth vs 6 oz. cloth. You have to make a decision based on
      the use of your boat (touring, racing, family knock-about) and see
      where a comprimise can be made. A racing canoe on calm waters can
      use a lighter mix of cloth and thinner wood than the same canoe
      frequenty used in white water or by the kids on a rocky shore. I
      hope this helps.
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