USCG Exam PracticeApplying tide corrections to charted depth
The height of a fixed bridge above the water is referenced to which datum on a US chart?
- A. Mean Lower Low Water (MLLW)
- B. Mean Sea Level (MSL)
- ✓ Mean High Water (MHW)Correct
- D. Mean Low Water (MLW)
Why C is correct
Heights of overhead features such as bridges and lights are referenced to Mean High Water (MHW), not MLLW. As the tide rises toward MHW, the vertical clearance beneath the bridge decreases. (Bowditch Ch. 9 §904)
Cited:Bowditch Ch. 9 §904