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), which represents the average of the lower low water heights. This datum is stated in the chart title and must be verified before plotting. (Bowditch Ch. 4 §403; Bowditch Ch. 9 §904)