Approximate tidal height at any hour between LW and HW using the rule of 1-2-3-3-2-1 twelfths of the range.
Formula
$$ \text{Fraction of range} = \{\tfrac{1}{12}, \tfrac{2}{12}, \tfrac{3}{12}, \tfrac{3}{12}, \tfrac{2}{12}, \tfrac{1}{12}\} $$Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $HW$ | High water height | m | tide table |
| $LW$ | Low water height | m | tide table |
| $Range$ | HW − LW | m | derived |
| $Fraction$ | Hours since LW → fraction of range | - | rule of twelfths |
Sources
- Admiralty Tide Tables - NP 201.