Rules of Twelfths
1 Hours of Tide Cycles Hourly Rise Cumulative Rise Percent of Rise
1 1/12 1/12 8%
2 2/12 3/12 16%
3 3/12 6/12 25%
4 3/12 9/12 25%
5 2/12 11/12 16%
6 1/12 12/12 8%

As you can see in the 3rd & 4th hour of the tide cycle the tide rose 50% of the total.

This rule is only a rough approximation. Wind and weather will affect the tides.

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