If a vessel has a draft of 39 feet and the echo sounder reads 27 feet depth, what is the difference in feet between draft and depth reading?

• A. 12
• B. 39
• C. 27
• D. 66

Answer: (A)

Understanding how these two measurements relate is key: draft is how far the hull sits below the waterline, while depth is how deep the water is from the surface to the seabed. To find the difference, subtract the depth reading from the draft: 39 feet minus 27 feet equals 12 feet. This difference shows how much deeper the hull would extend below the surface than the available water depth, which in real conditions would mean the vessel would be aground if this situation occurred. The other numbers would correspond to using the full draft or the full depth alone, or adding them together, which isn’t what’s being asked.