USCG Exam PracticeApplying tide corrections to charted depth
On a US nautical chart, soundings are referenced to which vertical datum?
- A. Mean High Water (MHW)
- ✓ Mean Lower Low Water (MLLW)Correct
- C. Mean Sea Level (MSL)
- D. Mean Low Water (MLW)
Why B is correct
US charts reference soundings to Mean Lower Low Water (MLLW), as stated in the chart title. This datum represents the average of the lower of the two daily low waters and is the baseline from which tide table heights are predicted. (Bowditch Ch. 4 §403; Bowditch Ch. 9 §904)