Last updated: 2026-04-14Contact: developer@captaincalc.com.tr
Reference basis: IMO/COLREG/STCW concepts, nautical practice, approved ship documents, and CaptainCalc calculation notes. Always verify operational decisions with official sources.
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Tidal Height Calculator (Rule of Twelfths)
Estimate tidal height at any point in the tidal cycle using the Rule of Twelfths approximation. Enter LW and HW heights from tide tables.
Formula reference & notes
The Rule of Twelfths divides a 6-hour tidal cycle into hourly increments where the tide rises/falls approximately 1 : 2 : 3 : 3 : 2 : 1 twelfths of the total range per hour.
Cumulative rise after each hour: 1/12, 3/12, 6/12, 9/12, 11/12, 12/12
⚠ This is an approximation for semi-diurnal tides. For accurate tidal work near dangerous shoals, always use official tide prediction software and correct for meteorological effects.
Cumulative rise after each hour: 1/12, 3/12, 6/12, 9/12, 11/12, 12/12
⚠ This is an approximation for semi-diurnal tides. For accurate tidal work near dangerous shoals, always use official tide prediction software and correct for meteorological effects.
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