🔍 Key Concepts

• Free surface effect and how it reduces metacentric height (GM) • Relationship between liquid surface area and loss of stability • How vessel displacement influences the magnitude of free surface effect

💭 Think About

• Think about what actually changes when liquid moves side-to-side in a slack tank: is it the length, the depth, or the area of the free surface that matters most? • Consider whether the amount of liquid changes the effect once the tank is already slack, or if something else is more critical. • Ask yourself how a very large ship and a very small ship, each with the same size slack tank, would be differently affected by free surface.

✅ Before You Answer

• Identify which option refers to surface dimensions rather than just one linear dimension. • Check which choice, if any, connects the effect to overall vessel displacement (weight of the vessel). • Verify that the option you pick is consistent with the idea that free surface effect is related to moment of inertia of the liquid surface, not just how full the tank is.