Stabilizers help to lessen the side-to-side motion, or roll, of a ship. The stabilizers are located on each side of the ship and extend outward in a manner similar to wings. They can be moved up and down to exert the force necessary to prevent the ship from rolling. Stabilizers are common on cruise ships, with one on each side, though larger ships may have two on each side.
A ship's stabilizers are often automatically piloted. When a ship's sensor system detects sea activity that pushes the ship to one side, the stabilizers are automatically extended from the hull with a hydraulic system and are piloted to exert force in the opposite direction.
The stabilizers can be operated independently of each other. One stabilizer can be used while the other remains inside of the ship in its compartment. When stabilizers are in use, they can reduce the fuel economy of the ship by creating a small amount of drag. Stabilizers only reduce the amount of roll; they cannot be used to reduce pitch. Pitching happens when the hull of the ship drops or goes up suddenly, causing the back end to rise or fall in opposition to the hull. To reduce pitch, a ship may be steered so the wave movement breaks against the side of the ship where the stabilizers can be used to counteract the movement.