The Tidal Curve Method
The Admiralty tidal curve is the standard method for finding the height of tide at any time. Step 1: Find the HW time and height, and LW height, from the tide tables. Step 2: Calculate the range (HW height minus LW height). Step 3: Find the time difference between your required time and HW (hours before or after HW).
Step 4: Enter the tidal curve at the appropriate time offset (hours before/after HW). Step 5: Read across to the curve, then down to find the height factor. Step 6: Multiply the range by the factor, and add to LW height. This gives the predicted height of tide at your required time.
Key Points
- Range = HW height − LW height
- Find hours before/after HW for your required time
- Enter curve at time offset, read height factor
- Height at time = LW height + (Range × factor)
- Use the spring or neap curve depending on the range