The Natchez Gage reads 20.6 feet. The high point on your towboat is 47 feet above the water. What is the vertical clearance as you pass under the Natchez Highway Bridge?
• air draft (height of the vessel above the waterline) • How bridge vertical clearances on inland rivers are tied to the local river gage (stage) • Using the formula: available clearance over your boat = (bridge clearance at that gage) − (your boat’s air draft)
• First, think about what the Natchez Gage reading tells you about the river level and how that affects the bridge clearance compared to low water. • Look up (or recall from your exam reference tables) the vertical clearance of the Natchez Highway Bridge at the current gage reading of 20.6 feet. • Once you know the bridge clearance above the water, subtract the 47‑foot height of your towboat to find how much space is left between your highest point and the bridge. • Compare your calculated clearance to the answer choices and see which one matches most closely.
• Be sure you are using the correct bridge clearance table for the Natchez Highway Bridge (Natchez, Mississippi River). • Confirm that you are subtracting the towboat height (47 ft) from the bridge clearance above the water surface, not from the gage height. • Double‑check unit consistency: all heights should be in feet and referenced to the same water surface level.
No comments yet
Be the first to share your thoughts!