USCG Exam PracticeChart symbols and abbreviations (Chart No. 1)
A US chart title states that soundings are in fathoms. A mariner reads a sounding of 3 near a shoal. What is the minimum depth indicated, and to what datum is it referenced?
- A. 3 feet, referenced to Mean Sea Level
- ✓ 3 fathoms (18 feet), referenced to Mean Lower Low WaterCorrect
- C. 3 fathoms (18 feet), referenced to Mean High Water
- D. 3 metres, referenced to Mean Lower Low Water
Why B is correct
When the chart title specifies fathoms, each sounding unit equals 6 feet, making a sounding of 3 equal to 18 feet. All US chart soundings are referenced to MLLW. The mariner must always verify the sounding unit in the chart title before plotting.
Cited:Bowditch Ch. 4 §403