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  5. Tide Height β€” Rule of Twelfths
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Tide Height β€” Rule of Twelfths

Estimate tide heights and stream rates hour-by-hour from HW/LW values, with a curve chart.

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Tidal curve (Rule of Twelfths)

Range: 4.40 m
OffsetTimeHeight (m)Phase
-6h06:170.80Flooding
-5h07:19.1666666666667421.17Flooding
-4h08:21.3333333333334851.90Flooding
-3h09:23.53.00Flooding
-2h10:25.6666666666665154.10Flooding
-1h11:27.8333333333334854.83Flooding
HW12:305.20High water
+1h13:32.1666666666665154.83Ebbing
+2h14:34.3333333333334854.10Ebbing
+3h15:36.53.00Ebbing
+4h16:38.6666666666665151.90Ebbing
+5h17:40.833333333333031.17Ebbing
+6h18:430.80Low water

Bonus: tidal stream rate (Rule of 50/90/100)

kn
WindowPhaseRate (kn)
12:30 – 13:32.166666666666515Hour 1 after HW1.25
13:32.166666666666515 – 14:34.333333333333485Hour 2 after HW2.25
14:34.333333333333485 – 15:36.5Hour 3 after HW2.50
15:36.5 – 16:38.666666666666515Hour 4 after HW2.25
16:38.666666666666515 – 17:40.83333333333303Hour 5 after HW1.25
17:40.83333333333303 – 18:43Hour 6 after HW0.00

⚠ For educational use only. Always use official tide tables and admiralty data for navigation.

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