And, it's only useful in areas with a semi-diurnal tide, right?


"Marc" wrote in message ...
ratio of tidal rise over time.

Rule of Twelfths
Shape assumed to be sinusoidal
Rise in 1/12ths
1 in first hour
2 in second
3 in third
3 in fourth
2 in fifth
1 in sixth

sometimes used as a rule of thumb for tidal current as well




On Tue, 2 Sep 2003 11:21:19 -0400, "Simple Simon"
wrote:

Since Booby is too ignorant to answer the following question,
I'll throw it out to the group as a whole.

What is the rule of 12ths and how would you use it?


S.Simon - a Captain who's serious about sailing