Sport Today

:>Once you pass the max. theoretical displacement
:>speed, then certainly no one could argue you were planing.
:
:Is this the same a hull speed?  How fast is it?

One point three four times the square root of waterline length(in
feet) gives hull speed in knots.

(Not many people know that)  :o)

RobSm

The formula given above by RobSm is, indeed, approximately correct. Simply
stated, the tern "hull speed" refers to the approximate speed at which a
hull starts to climb its bow wave. A nine-foot board has a "hull speed" of
about 4 knots.

The formula's limitations: while it does apply to planing hulls, it's not
very useful in connection with them -- not even longboards, which exceed
hull speed even when going upwind in moderate conditions. You're right to
think the formula is most useful in connection with high-displacement
non-planing hulls.

KW