USCG Exam PracticeApplying tide corrections to charted depth
A bridge is charted with a vertical clearance of 25 feet at MHW. The tide tables show the current water level is 2 feet below MHW. What is the actual vertical clearance under the bridge at this time?
- A. 23 feet
- B. 25 feet
- ✓ 27 feetCorrect
- D. The clearance cannot be determined without the charted depth beneath the bridge.
Why C is correct
Per the Light List Bridge Clearance Annotation, bridge vertical clearances on US charts are given at MHW. When the water level is below MHW, the clearance increases. With the water 2 feet below MHW, actual clearance is 25 ft + 2 ft = 27 ft.