Question:
I have just come across a reference to Bruce number. I suspect
that it is a dimensionless number relating the cube root of
displacement to the square root of sail area. It does not seem
to work using metric units. Any suggestions why? Is it based in
incompatible units?
Answer:
It is the ratio of the square root of the sail area to the cube root of
the displacement. It "should be" about 1 for a crusier and 1.3 for a dingy.
Its not actually dimensionless. Its feet per pound, sort of. Just happens
to work out to be close to unity. Not the same in metric.
Its good for estimating the sail area required for a boat, also for
handicapping races.
