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Ship stabilizing gyroscopes are a technology developed in the 19th century and early 20th century and used to stabilize roll motions in ocean-going ships. It lost favor in this application to hydrodynamic roll stabilizer fins because of reduced cost and weight. However, since the 1990s, there is renewed interest in the device for low-speed roll stabilization of vessels (Seakeeper, Quick MC2, etc.). Unlike traditional fins, the gyroscope does not rely on the forward speed of the ship to generate a roll stabilizing moment and therefore can stabilize motor yachts while at anchor. However, the latest generation of "zero speed" fins stabilizers (CMC, Humphree, etc.) can stabilize yachts while at anchor thanks to their eccentricity with respect of the shaft.
The World War I transport , completed in 1917, was the first large ship with gyro stabilizers. It had two 25-ton, diameter "Italian Liner To Defy The Waves"
Popular Mechanics, April 1931. The ship gyroscopic stabilizer typically operates by constraining the gyroscope's roll axis and allowing it to "precess" either in the pitch or the yaw axes. Allowing it to precess as the ship rolls causes its spinning rotor to generate a counteracting roll stabilizing moment to that generated by the waves on the ship's hull. Its ability to effectively do this is dependent on a range of factors that include its size, weight, and angular momentum. It is also affected by the roll period of the ship. Effective ship installations require rotors having a weight of approximately 3% to 5% of a vessel's displacement. Unlike hydrodynamic roll stabilizing fins, the ship gyroscopic stabilizer can only produce a limited roll stabilizing moment that may be exceeded as the wave height increases. Otherwise, it is not unusual for the manufacturer to recommend that the unit not be used at sea in large waves. Instead of providing stabilization, the same technology can be used in an active way to control the orientation, as
Schlicks ship stabilizing device (19th century)
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The World War I transport , completed in 1917, was the first large ship with gyro stabilizers. It had two 25-ton, diameter flywheel
A flywheel is a mechanical device which uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, assu ...
s mounted near the center of the ship, spun at 1100 rpm by AC motors. The gyroscopes' cases were mounted on vertical bearings. When a small sensor gyroscope on the bridge sensed a roll, a servomotor
A servomotor (or servo motor) is a rotary actuator or linear actuator that allows for precise control of angular or linear position, velocity and acceleration. It consists of a suitable motor coupled to a sensor for position feedback. It also r ...
would rotate the gyros about a vertical axis in a direction so their precession would counteract the roll. In tests this system was able to reduce roll to 3 degrees in the roughest seas.
One of the most famous ships to first use an anti-rolling gyro was the Italian passenger liner , which first sailed in November 1932. It had three flywheels which were 13 feet in diameter and weighed 108 tons.Popular Mechanics, April 1931. The ship gyroscopic stabilizer typically operates by constraining the gyroscope's roll axis and allowing it to "precess" either in the pitch or the yaw axes. Allowing it to precess as the ship rolls causes its spinning rotor to generate a counteracting roll stabilizing moment to that generated by the waves on the ship's hull. Its ability to effectively do this is dependent on a range of factors that include its size, weight, and angular momentum. It is also affected by the roll period of the ship. Effective ship installations require rotors having a weight of approximately 3% to 5% of a vessel's displacement. Unlike hydrodynamic roll stabilizing fins, the ship gyroscopic stabilizer can only produce a limited roll stabilizing moment that may be exceeded as the wave height increases. Otherwise, it is not unusual for the manufacturer to recommend that the unit not be used at sea in large waves. Instead of providing stabilization, the same technology can be used in an active way to control the orientation, as
control moment gyroscope
A control moment gyroscope (CMG) is an attitude control device generally used in spacecraft attitude control systems. A CMG consists of a spinning rotor and one or more motorized gimbals that tilt the rotor’s angular momentum. As the rotor tilts ...
s do in spacecraft, to provide attitude control
Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc.
Controlling vehicle ...
.
See also
*Ship stability
Ship stability is an area of naval architecture and ship design that deals with how a ship behaves at sea, both in still water and in waves, whether intact or damaged. Stability calculations focus on centers of gravity, centers of buoyancy, the ...
*Stabilizer (ship)
Ship stabilizers (or stabilisers) are fins or rotors mounted beneath the waterline and emerging laterally from the hull to reduce a ship's roll due to wind or waves. ''Active fins'' are controlled by a gyroscopic control system. When the gyr ...
References
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Schlicks ship stabilizing device (19th century)
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