USCG Exam PracticeTides and currents — predictions and corrections
A vessel has a draft of 9 feet. The chart shows a sounding of 7 feet at a shoal. The predicted height of tide at that location is +3 feet. What is the vessel's underkeel clearance over the shoal?
- ✓ 1 footCorrect
- B. 5 feet
- C. The vessel will ground; there is no clearance
- D. 4 feet
Why A is correct
Actual depth equals charted sounding plus predicted height of tide: 7 + 3 = 10 feet. Underkeel clearance equals actual depth minus draft: 10 − 9 = 1 foot.
Cited:Bowditch Ch. 9 §904