🔍 Key Concepts

• Free surface effect (FSE) and how it reduces GM (metacentric height) • Using the second moment of area of a rectangular tank (or deck area) for free surface moment: I = (L × B³) / 12 • Relationship between free surface moment, displacement, and the reduction in GM

💭 Think About

• How do you convert the deck dimensions (42 ft × 28 ft) into the free surface moment using the correct formula for a rectangular area? • Once you have the free surface moment, how is it divided by the vessel’s displacement (368 tons) to obtain the reduction in GM? • Where (if at all) does the given 36 tons of water weight actually matter in calculating free surface reduction for a wide, slack surface?

✅ Before You Answer

• Confirm you are using B³ (breadth cubed) and not length cubed in the free surface formula. • Make sure the displacement used in the denominator is the vessel’s total displacement (368 tons), not the 36 tons of shipped water. • Check that all units are consistent: deck dimensions in feet, displacement in tons, and that your result for GM reduction is in feet.