QLW wrote in message
...
Steve,
As I suspected, my Engineer Friend went on in great detail to
explain why
stepping the mast on the deck or on the keel has no effect on
the strength
of the mast in compression. While some small benefit could
conceivably be
gained by helping to keep the mast in column, he claimed that
would only
occur in the case of a flawed design. If the mast were stepped
on a poorly
supported deck then all of the thinking changes...but that's a
deck problem
not a mast problem. Good reasons for either stepping the mast
on the keel
or on the deck can be argued, but compressive strength is not
one of them.

I think you're talking slightly at cross-purposes here.

Ignoring bendy masts, keel stepping (and its corollary, deck
support) doesn't add to strength in compression (as such), but it
increases the bend stability of a mast under compression. Bend
disturbances will occur due to inertia effects in a seaway, and
the various sail tensions in different sailing conditions. This
is not a design flaw, it's a design case. To keep the mast stable
under compression, these bending moments must be resisted, either
by using a large enough cross section, or by constraining
movement with stays and deck support. With appropriate support,
smaller cross sections can be used.

Most vessels designed to withstand extreme conditions (ignoring
racing) prefer straight masts. Keel stepping either adds to rig
strength, or can be used to reduce weight aloft. An engineer will
correctly say it makes no difference to the (pure) compression
strength of a cross section. But as part of a rigging system, all
other things being equal, it does add strength.

JimB