Wayne.B wrote:
On Thu, 20 Nov 2003 03:44:31 +1100, K Smith wrote:


Wood is not a very strong material at all. Tougher hardwoods have very
moderate strength in compression, but other than that wood is a very
weak material with low resistance to flexing+


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Not at all true, wood has a very high strength to weight ratio. You
are confusing strength with stiffness. They are two entirely
different properties.


With respect I don't think so indeed wood is of such low structural
strength at any sort of unsupported span is usually limited by the
weight of the wood itself. i.e. if you get the books out & design a
wooden beam to carry a heavy load over spans that are commonplace with
say RSJs, composites or even ferro, the problem with wood becomes that
the beam sags under it's own weight, without any load!!!

It's reasonably good at holding leaves up, flexible enough to survive
wind storms (maybe sometimes) & porous enough to allow them some water
etc, so long as those leaves a manufacturing food to keep it in good
working order. As soon as it's removed from it's roots & leaves life
support it just become mulch indeed even trees throw those limbs off
rather than risk the rot spreading. As a structural material it's not
much good. Add a moist boat type environment & that's why boats are
built these days of almost anything other than wood. I love my old
wooden boat, but .......



K