51940Re: water ballast vs lead, iron, etc
- Dec 1, 2006Guy,
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.
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