What is the vertical clearance between the...

Question 1 of 29218fork_5a520c4e26fa446f8bc

What is the vertical clearance between the highest point of your towboat, if it is 45 feet above the water, and if the Natchez Gage reads 23.4 feet when passing under the Natchez-Vidalia Westbound Highway Bridge?

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Question 1 of 29218

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🔍 Key Concepts

• Bridge clearance tables on river charts often give clearance at a specific reference river stage or gage height • How to adjust clearance when the river level rises or falls from the reference level • Relating the height of your towboat above the water to the available bridge clearance to find vertical clearance between the two

💭 Think About

• What does the published bridge clearance assume about the river stage or Natchez Gage reading, and how do you correct it when the gage is higher than that reference? • If the water level rises, does the available clearance between the water surface and the bridge increase or decrease, and by how much per foot of gage change? • Once you know the distance from the water to the bridge at the current gage, how do you subtract the towboat’s air draft (45 feet) to get the remaining clearance above your boat?

✅ Before You Answer

• Be sure you know the reference gage height and published clearance for the Natchez-Vidalia Westbound Highway Bridge (from the exam’s chart or table) before doing any math • Carefully track units in feet and whether you are adding or subtracting when the river is higher than the reference gage • After computing the available water-to-bridge clearance at the current gage, subtract your boat’s 45 ft air draft to get the final vertical clearance