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 is also the datum from which NOAA Tide Tables predict heights of tide. Bowditch Ch. 4 §403 and Ch. 9 §904 both confirm this.