🔍 Key Concepts

• Free surface effect and how it reduces a vessel's metacentric height (GM) • The difference between a tank that is completely full, completely empty, or slack (partially filled) • How the depth of liquid and breadth of tank influence free surface moment

💭 Think About

• In which condition can the liquid move (slosh) the most from side to side when the ship heels? • What happens to the ship’s stability when the center of gravity is raised due to liquid shifting in multiple tanks? • Compare the free surface in a tank that is nearly full versus one that is about half full—where can the liquid surface move over the widest horizontal area?

✅ Before You Answer

• Verify which condition creates a wide, free liquid surface that can shift laterally. • Check which option gives a ‘slack tank’ rather than a fully pressed-up or completely empty tank. • Confirm that full or empty tanks do not have free surface in the same way as partially filled tanks.