Module 11 - Tides & Tidal Streams
The Tidal Curve Method
Use the tidal-curve method printed for the named standard port and the edition in use. Begin with the correct HW and LW times and heights, calculate the range, establish whether the tide is rising or falling, and find the required time before or after the reference HW.
Follow the supplied axes and instructions: a curve may express height above LW, fall from HW, or a percentage/factor of range. Read the result in the direction stated by that publication, apply it to the corrected range and sense-check that the answer lies between the relevant LW and HW heights.
Choose or interpolate between spring and neap information only as the source page directs. Record the time zone, port, date, source edition, interpolation and rounding so another navigator can reproduce the answer, then add an operational safety margin rather than treating the prediction as observed water level.
- Range = HW height − LW height
- Find hours before/after HW for your required time
- Identify whether the supplied curve measures rise from LW or fall from HW
- Follow the exact axes and instructions printed for that standard port
- Interpolate spring/neap information only as the publication directs
- Record source, time zone, interpolation, rounding and safety margin
Continue studying Tides & Tidal Streams
This public lesson is part of Revision Module 11. Full revision access adds the guided Learn, Practise and Test flow, flashcards and revision progress.