ASA point? :-)

--
"j" ganz @@
www.sailnow.com

"Bart Senior" .@. wrote in message ...
Good point Jeff.

"Jeff" wrote

While the Rule of 12ths is a very handy tool for estimating the tide
height at any point in the cycle, I would be very careful of using to
extrapolate total range from one hour's observation. For instance, if
your observation were off by one inch, then you might mis-estimate the
full range by a foot.

On a related topic, sometimes people will claim that the Rule of 12ths
also applies to current estimation. This is generally not true. The
strength of the current through the cycle is highly dependent on the
local geography. In particular, the strong currents that are generated
by tidal differences on connected bodies of water (Hell Gate, Cape Cod
Canal, etc.) ramp up very quickly and their chart is more of a square
wave, than a sine.