🔍 Key Concepts

• Free surface effect and how it reduces initial stability (GM) • Relationship between moment of inertia of the free surface and vessel displacement • How the same free surface in a larger vs. smaller ship affects GM

💭 Think About

• Think about the formula for free surface correction: how does displacement appear in that relationship? Is it in the numerator or denominator? • Imagine two tanks with the same free surface, one on a very small vessel and one on a very large vessel. Which vessel will suffer a greater loss of stability from that same free surface? • Consider what happens to the ship’s ability to resist heeling as overall displacement gets larger. Does the same free surface moment represent a bigger or smaller fraction of the ship’s stability?

✅ Before You Answer

• Recall that free surface correction (FSC) is proportional to the free surface moment divided by the ship’s displacement • Check whether increasing displacement makes the loss of GM from a given free surface larger or smaller • Verify that you’re thinking about a given tank/free surface and not changing both tank size and ship size together