What do stabilizers do?
Explorer of The Seas handling some large waves.
The purpose of stabilizers is to reduce the roll (i.e., the sideways motion) of a ship.
Today, all modern cruise ships have stabilizers. Most ships have two stabilizers, one on each side of the ship. Larger ships like Cunard Line’s Queen Mary 2 and Royal Caribbean’s Voyager, Freedom and Oasis class ships, have four stabilizers, two on each side.
The stabilizers are shaped like airplane wings and extend out from the side of the hull in a perpendicular fashion when in use. They can pivot up and down like the ailerons on an airplane’s wings. Consequently, as the water flows over a stabilizer it can be turned upwards or downwards to exert dive or lift.
When a sensor detects that a wave is pushing the ship one way, the ship’s systems automatically pivot the stabilizers so as to exert pressure in the opposite direction. Captain William Wright of Royal Caribbean reports: “they eliminate about 85% of the roll of the vessel.”
When the ship is in port or when the seas are calm, the stabilizers can be folded back hydraulically into compartments along the side of the hull. Stabilizers can be deployed independently and so the ship’s officers have the option of deploying the stabilizers on one side of the ship or on both sides to suit the sea condition.
Stabilizers do create some drag and thus can in theory reduce speed and fuel efficiency. However, any such loss has to be balanced against the savings in speed and fuel efficiency resulting from reducing the ship’s motion.
Unfortunately, stabilizers do nothing to eliminate pitching - - the motion made when the front of the ship goes down and the back goes up and vice versa. The better a ship is at cutting through the waves, the less it will be subject to pitching. Consequently, a ship that is designed with a long, narrow bow will do better in such situations than one with a wide, blunt bow. This is because a ship with a blunt bow will attempt to climb over the wave thereby causing the bow to rise more or will be forced downward thereby causing the stern to rise more than if the ship cut through the wave.
If feasible, the officers will set a course so that the waves are striking the side of the ship rather than the bow because that brings the stabilizers into play.
Cruise ship FAQs - - What do stabilizers do?