USCG Exam PracticeChart symbols and abbreviations (Chart No. 1)
A chart title block states soundings are in fathoms. A sounding figure of '3' is read on the chart. What is the actual depth referenced to MLLW?
- A. 3 feet
- B. 3 metres
- ✓ 18 feetCorrect
- D. 30 feet
Why C is correct
US charts may express soundings in feet, fathoms, or metres, and the unit is stated in the chart title. One fathom equals 6 feet; therefore a sounding of 3 fathoms equals 18 feet, referenced to MLLW. Failing to verify the unit in the title block is a common source of navigational error. (Bowditch Ch. 4 §403)
Cited:Bowditch Ch. 4 §403