Jeff Morris wrote:
Fred Miller wrote:
I know that the peak or trough of a tide is not linear with time
but I can't
remeber if it is 1/6, 2/6, and 3/6 for each of the three segments
or if it
si different. Can anyone help, please.


Yes, you have it sort of right, but not quite. Its often called the
"Rule of Twelves." One twelfth of the height come in in the first
hour, two twelfths in the second, three in the third, three in the
forth, two in the fifth, one in the sixth. Thus the fastest change
will
occur at mid tide.

Good info, thanks for posting.


Sometimes the Rule of Twelves is applied to currents, but that is
often
not correct. When the current is caused by large bodies of water of
differing heights connected by a narrow channel, the current gets up
to
speed rather quickly - sometimes reaching half speed in less than 30
minutes from slack tide.

So, and please excuse a really stupid question, but slack tide refers
to the hour or so on both sides of low tide when the tide rising or
falling most slowly?
I've always seen this term but never been precisely sure of the
definition.

richforman