That's why triangular sections have the greatest rigidty for
their cross section area, and square sections are more rigid than oval
or round.


Nav wrote:
I think you may be confusing a truss with a section.

Nope.

... For bending in
plane

In what plane?

... the most rigid section per unit weight

Did I say "per unit weight"? No I said cross section area.

... is close to a T
section with the top under compression and the bulb (or smaller bottom
plate) at the bottom in tension.

You're describing an asymmetric I-beam.

Now, think for a moment... have you seen any sailboat booms shaped like
I-beams?

No, you haven't. But if you've looked at pictures of fancy hi-dollar
racing yachts, you have seen triangular section booms.

Why is that, Navvie?


Maybe you better go call up Bruce Farr and tell him he's been getting it
wrong. He'll probably offer you a job.

DSK