Dry Cargo Test 1 Practice

Free surface effect happens when a space in the ship contains liquid or unsettled cargo that can move freely. As the vessel heels or rolls, the liquid surface or loose material shifts toward the low side, pulling the center of gravity downward and reducing the righting moment (GM). That makes the ship less stable and can worsen even small motions into larger angles of heel, especially in rough seas. The effect is strongest when tanks or holds are only partially filled and have enough open area for the contents to move. An example where it matters is a tanker or bulk carrier with partially filled cargo tanks or holds. If the ship encounters a turn or a heavy roll, the liquid or loose cargo can slosh from side to side, quickly changing trim and stability. To minimize the risk, fill tanks where possible or empty them, use internal baffles or multiple compartments to limit movement, segregate different liquids as needed, and secure or restrict cargo movement with proper dunnage and stowage.