Chart Navigation & Plotting · Tides
To find the actual depth of water at a given time, you:
- ASubtract the height of tide from the charted depth
- BAdd the bridge clearance to the sounding
- CUse the charted depth alone
- DAdd the height of tide to the charted depth (sounding)✓ Correct
Explanation
Charted soundings are referenced to a low-water datum (MLLW), so the real depth equals the charted sounding plus the predicted height of tide. At a negative (minus) tide, the actual depth can be less than charted.
Authority: Tide Tables; Chart No. 1
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