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Free tidal-curve workbench

Read a tidal curve, then practice the calculation

Direct answer

Height of tide is measured above Chart Datum. Use the high- and low-water heights to find the range, read the curve factor for the required time, then apply that factor to the range. Add the resulting height of tide to a charted depth before checking under-keel clearance.

Explore
Move through the six-hour curve
Practice
Generated height problems
Feedback
Factor, range, and worked answer
Cost
Free, no login

This is a simplified learning curve, not a prediction for a real harbour. Use official tide tables, local tidal curves, almanacs, and safety margins for navigation.

Open the full tides module

Interactive practice

Tidal heights trainer

This is a smooth teaching curve for practicing the method. Real tidal curves are port-specific: for passage planning, use the published curve, predictions, secondary-port corrections, and time zone for the port and date concerned.

-6h-5h-4h-3h-2h-1hHW+1h+2h+3h+4h+5h+6h1.2m2.0m2.8m3.7m4.5m4.5mHours from HW (12:00)Height (m)

0h from HW

Range: 3.3m
Factor: 1.00
Height at time: 4.5m
Calc: 1.2 + (3.3 × 1.00) = 4.5m