Free Surface Effect Law and Legal Definition

Free surface effect is the change in stability of a vessel caused by liquids moving about freely in a tank or hold. As a vessel rolls, liquids in tanks or breached compartments accentuate the roll by moving freely from side to side of the tank accumulating first on one side and then the other, and may adversely affect the stability of the ship. The free service effect can be reduced by having baffles in a tank to reduce the free movement or by either emptying the tank or filling it completely.