USCG Exam PracticeChart symbols and abbreviations (Chart No. 1)
A chart shows a bridge clearance figure of 45 feet above the bridge symbol. To what water level is this clearance referenced?
- A. Mean Lower Low Water (MLLW)
- B. Mean Sea Level (MSL)
- ✓ Mean High Water (MHW) or High Water Spring, depending on the chartCorrect
- D. Mean Low Water (MLW)
Why C is correct
Overhead clearance figures for bridges and power lines are referenced to either Mean High Water or High Water Spring depending on the chart, representing the least available vertical clearance at high water. This is distinct from soundings, which are referenced to MLLW. (Light List — Overhead Clearance)