Guy,

at your "The Stiffness of an Advanced Sharpie" at

http://faculty.valpo.edu/gvandegr/ there is this:

"This axis of rotation ensures that the total area of this

underwater section remains constant. Close inspection of the graph

indicates that the rotation slightly increases the area under the

waterline. Hence the rotation is accompanied by a slight lifting of

the boat, which becomes important only at large angle, I believe."

What lifts the boat? How is it lifted if it remains the same mass?

(disregarding any lifting component of the forces on any sail)

I can imagine wider hull sections aft coming into play as they are

immersed (more) with increasing heel, and so perhaps lifting this

represented midships cross section. If this is the case then the

data set gained from only this representative cross section would be

insufficient to construct a generally representative model.

If this is not the case it would appear that, as the boat is not

able to just arbitrarily "lift" by some unknown means, then the

assumptions made from this represented cross section are somewhat

erroneous and therefore any further calculations based on them are

also going to be in error. My calculus skills are too rusty to

comment on your derived equations, and the insights and intuitions

gained, other than to raise the point that any initial error in

assumptions may be compounded, perhaps more than trivially so.

Graeme