"Tom Dacon" wrote in message
...
It's a mechanical engineering issue. A mast (called a column by mechanical
engineers) that's supported only at the ends is less strong in compression
than a column that's supported at two points at one end. The support at
the
mast step, for a keel-stepped mast, allows the mast to take more
compression
before failing than a deck-stepped mast can. Because the stays and shrouds
take sailing loads almost parallel to the mast, the mast column comes
under
significant compression load.

While I like the idea of a keel stepped mast, I'm skeptical about the
reasoning above. I'm not an engineer but I have a good friend that
is...and he has a lot of aircract and boat design experience...so I'll run
this thread by him this afternoon and get his input before saying more. He
is currently building a 90' cat with an unstayed rotating mast but that is
an intirely different problem. No compresson loads there, but at one time
he was considering a stayed mast and must have done the thinking on it.