Displacement (ship)

Displacement or displacement tonnage is the weight of water that a ship pushes aside when it is floating, which in turn is the weight of a ship (and its contents). It is usually applied to naval vessels rather than commercial ones, and is measured when the ship's fuel tanks are full and all stores are aboard.[1][2] Merchant vessels use other measures such as net tonnage, gross tonnage, or deadweight tonnage.

The more heavily loaded a ship is, the lower it sits in the water. "Designated displacement" is a measurement the weight of water a ship displaces of when fully loaded and submerged to her load lines.