🔍 Key Concepts

• Free surface effect (FSE) and how it reduces GM • Using the second moment of area for a rectangular free surface: I = (L × B³) / 12 • The free surface correction formula that uses I, displacement, and specific weight of water or relative density

💭 Think About

• First, compute the free-surface moment of inertia of the shipped water on the after deck using its length and breadth. Which dimension is cubed? • Then think about how the vessel’s total displacement (in tons) relates to the correction to GM caused by the free surface. Should the correction be bigger or smaller on a heavier vessel? • Check whether the actual weight of the water (51.5 tons) is directly used in the free-surface correction, or if the correction depends mainly on the free surface area and tank breadth.

✅ Before You Answer

• Be sure you are using consistent units (feet for dimensions, tons or long tons for displacement). • Confirm that you are using the correct breadth (B) for the free surface (the 31' deck breadth, not the ship’s length). • Verify that you are applying the free surface correction to GM formula correctly, including dividing by the vessel’s total displacement of 477 tons.