🔍 Key Concepts

• Ullage is the empty space in a tank above the liquid • Difference between a sounding (measuring liquid depth) and an ullage (measuring empty space) • Where measurements are usually taken from in a cargo or ballast tank (reference point at the top vs. bottom)

💭 Think About

• Ask yourself: Does ullage measure how much liquid is in the tank, or how much space is left above the liquid? • From what fixed point are ullage measurements normally taken—top of tank, bottom of tank, or side of tank? • Which choice describes a measurement that ends at the surface of the liquid, not the bottom of the tank?

✅ Before You Answer

• Confirm that ullage relates to the space above the liquid, not the liquid depth itself • Ensure the starting point is a fixed reference at the top (such as the top of the tank or sounding tube) • Eliminate any option that measures down to the tank bottom rather than to the liquid surface