USCG Exam PracticeApplying tide corrections to charted depth
A chart shows a sounding of 12 feet. The predicted height of tide is -1 foot (a negative tide). The vessel's draft is 10 feet. What is the underkeel clearance?
- A. 3 feet
- B. 2 feet
- ✓ 1 footCorrect
- D. 0 feet
Why C is correct
Actual depth equals charted sounding plus predicted height of tide: 12 + (-1) = 11 feet. Underkeel clearance equals actual depth minus draft: 11 - 10 = 1 foot. A negative tide reduces depth below the charted sounding. (Bowditch Ch. 9 §904)
Cited:Bowditch Ch. 9 §904