Module 11 - Tides & Tidal Streams
Using Tide Tables
ADMIRALTY Tide Tables provide daily high- and low-water times and heights for standard ports, plus differences and methods for secondary ports. Almanacs and authorised digital services may present the same planning information in a different layout. Use a current product suitable for the area and follow its instructions.
First confirm the place and date. Then read the time basis exactly as displayed. UK paper tables commonly use UT (GMT), while a digital product may display a selected local or zone time. Add one hour for British Summer Time only when the source is in UT and BST applies; never add it to a value already displayed in local civil time.
For an intermediate height, copy the high and low waters that bracket the required time and use the port's supplied curve or method. Predictions describe astronomical water level, not an observation: pressure, wind, surge and waves can alter the level actually found.
- Confirm publication, port and date before copying values
- Read the displayed time basis instead of assuming UT or local time
- Use the bracketing high and low waters
- Use the supplied port curve or method
- Allow for meteorological effects and operational margins
Optional quick check
Section 4 of 8
A tide service explicitly displays times in BST. What conversion is needed for a passage plan also kept in BST?
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