Tidal gate calculator (Rule of twelfths)
This calculator calculates tidal gates using the rule of twelfths, estimating the height of the tide at any time, given only the time and height of high and low water.
This page exists due to the efforts of the following people:
 | Timur
|
This content is licensed under Creative Commons Attribution/Share-Alike License 3.0 (Unported). That means you may freely redistribute or modify this content under the same license conditions and must attribute the original author by placing a hyperlink from your site to this work https://planetcalc.com/2450/. Also, please do not modify any references to the original work (if any) contained in this content.
This calculator calculates tidal gates using the rule of twelfths to find out tidal gate open and close times.
The rule assumes that the flow rate of a tide increases smoothly to a maximum halfway between high and low tide before smoothly decreasing to zero again and that the interval between low and high tides is approximately six hours. The rule states that in the first hour after low tide, the water level will rise by one-twelfth of the range, in the second hour two twelfths, and so on according to the sequence - 1:2:3:3:2:1
The calculator uses the rule of twelfths to find out hour points and then uses a linear approximation to find out tidal gate open and close time inside the hour.
Note that the rule is a rough approximation only and should be applied with great caution when used for navigational purposes.
For example, this rule assumes that all tides behave regularly; this is not true for geographical locations, where there are double high waters or double low waters. This rule also assumes that the period between high and low tides is six hours, but this is an underestimate and can vary anyway.
Officially produced tide tables should be used in preference whenever possible.
Comments