Navigation General · Tides
At a mixed semidiurnal tidal station, how many high waters and low waters typically occur each day?
- AOne high water and one low water
- BTwo high waters and two low waters of equal height
- CThree high waters and three low waters
- DTwo unequal high waters and two unequal low waters✓ Correct
Explanation
A mixed semidiurnal tide has two highs and two lows per tidal day, but the heights are unequal — a higher high water, lower high water, higher low water, and lower low water. This pattern is common on the US West Coast and Hawaii.
Authority: NOAA Tide Tables
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