Work out trim and stability instantly with clear inputs, formula shown and shareable results.
Metacentric height GM is the distance between the centre of gravity and the metacentre, KM minus KG, reduced by the free surface correction for partly filled tanks. Righting moment at small angles is displacement times GM times sin(heel), so GM is the single number that decides whether a ship is stiff, tender or unsafe.
Metacentric height
GM = KM - KG - free surface correction; righting moment = displacement x GM x sin(heel)
Marine results are planning estimates only. Verify against the vessel's approved stability booklet, loading manual, class society rules and applicable maritime regulations before loading or sailing.
Most codes require at least 0.15 m of fluid GM in all conditions, and many operators keep 0.3-0.5 m for comfort and margin.
Liquid in a partly filled tank shifts to the low side as the ship heels, moving the centre of gravity and effectively raising KG.