The highest point on your towboat is 53 feet...

Question 1 of 2707066636eea28f7522a1c51b338

The highest point on your towboat is 53 feet above the water, and the Helena Gage (mile 663 AHP) reads 6.7 feet. What is the vertical clearance when you pass under the Helena Highway Bridge in Helena?

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Question 1 of 27070

🔍 Key Concepts

• Vertical clearance is the distance from the water surface up to the lowest part of the bridge structure. • On inland rivers, published bridge clearances are usually given at a reference gage height (often 0.0 or a specific stage). • To solve, you need to adjust the charted bridge clearance using the current gage reading before comparing it with your towboat height.

💭 Think About

• Think about how the gage reading affects the clearance: if the river is higher than the reference stage, does the clearance increase or decrease? • What information do you need from the river tables or bridge list about the Helena Highway Bridge to start the calculation? • Once you adjust the bridge clearance for the current gage, how do you figure out whether your 53-foot towboat will fit and what the remaining clearance is?

✅ Before You Answer

• Be sure you understand whether the published bridge clearance is given at 0.0 gage or at a specific stage on the Helena Gage. • Carefully apply the difference between the reference gage and the current gage (6.7 ft)—including the correct sign (add or subtract). • After finding the adjusted bridge clearance, subtract your 53 ft air draft to find the remaining vertical clearance, then match that to the closest choice.