18. The Vicksburg Gage reads 31.9 feet. The high point on your towboat is 43 feet above the water. What is the vertical clearance as you pass under the Vicksburg Highway 80 Bridge?

Calculate vertical clearance by subtracting the river stage from the bridge's charted clearance, then subtract the towboat's air draft. The bridge's vertical clearance at 0.0 feet on the Vicksburg Gage is 116.2 feet. With a river stage of 31.9 feet, the water-to-bridge clearance is 84.3 feet. Subtracting the towboat's 43-foot air draft yields a vertical clearance of 41.4 feet.