🔍 Key Concepts

• Ullage is the empty space in a tank above the liquid cargo • On tankers, measurements need a fixed, repeatable reference point that does not change as the ship loads or trims • Difference between a reference on deck versus inside the tank (ceiling or bottom)

💭 Think About

• Which point will stay constant and easy to access for every measurement, regardless of how full the tank is? • Which option matches the common practice of lowering a tape or electronic ullage gauge from the deck into the tank? • Would a point on the tank top or tank ceiling be practical for routine sounding/ullaging operations on a loaded tanker?

✅ Before You Answer

• Make sure the reference point is a fixed structural point that does not move with cargo level • Confirm that the reference point allows ullage tapes or gauges to be used from the deck safely and consistently • Eliminate any options that would require going inside the tank for every measurement, as this is not normal practice on tankers