Stabilizer (ship)
Encyclopedia
Ship stabilizers are fins mounted beneath the waterline and emerging laterally. In contemporary vessels, they may be gyroscopically
controlled active fins, which have the capacity to change their angle of attack
to counteract roll caused by wind or waves acting on the ship.
The bilge keel
is an early 20th century predecessor. Although not as effective at reducing roll
, bilge keels are cheaper, easier to install, and do not require dedicated internal space inside the hull
.
In November 1932 the ship Conte di Savoia made its maiden voyage. It had three huge gyroscopes fitted low down in a forward hold. These rotated at high revolutions and were designed to eliminate rolling - a persistent problem on the rough North Atlantic crossing that affected all shipping lines. Each of the three flywheels was 13 feet in diameter and weighed 108 tons.
The first mention of automatic stabilizers for ships was in 1932, by an engineer working for General Electric.
The first use of fin stablizers on a ship was by a Japanese cruise liner in 1933.
In 1934 a Dutch liner introduced one of the world's most unusual ship stabilizer systems, in which two large tubes were mounted on each side of the ship's hull with the bottom of the tubes open to the sea. The top of the tubes had compressed air or steam pumped in. As the ship rolled the side it was rolling to would fill with water and then compressed air or steam would be injected to push the water down countering the roll.
Gyroscope
A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...
controlled active fins, which have the capacity to change their angle of attack
Angle of attack
Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...
to counteract roll caused by wind or waves acting on the ship.
The bilge keel
Bilge keel
A bilge keel is used to reduce the hull's tendency to roll. Bilge keels are employed in pairs . A ship may have more than one bilge keel per side, but this is rare. Bilge keels increase hydrodynamic resistance to rolling, making the ship roll less...
is an early 20th century predecessor. Although not as effective at reducing roll
Ship motions
Ship motions are defined by the six degrees of freedom that a ship, boat or any other craft can experience.- Translation :HeaveSwaySurge-Vertical axis:Vertical axis, or yaw axis — an axis drawn from top to bottom, and perpendicular to the other two axes...
, bilge keels are cheaper, easier to install, and do not require dedicated internal space inside the hull
Hull (watercraft)
A hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present. The line where the hull meets the water surface is called the waterline.The structure of the hull varies depending on the vessel type...
.
In November 1932 the ship Conte di Savoia made its maiden voyage. It had three huge gyroscopes fitted low down in a forward hold. These rotated at high revolutions and were designed to eliminate rolling - a persistent problem on the rough North Atlantic crossing that affected all shipping lines. Each of the three flywheels was 13 feet in diameter and weighed 108 tons.
The first mention of automatic stabilizers for ships was in 1932, by an engineer working for General Electric.
The first use of fin stablizers on a ship was by a Japanese cruise liner in 1933.
In 1934 a Dutch liner introduced one of the world's most unusual ship stabilizer systems, in which two large tubes were mounted on each side of the ship's hull with the bottom of the tubes open to the sea. The top of the tubes had compressed air or steam pumped in. As the ship rolled the side it was rolling to would fill with water and then compressed air or steam would be injected to push the water down countering the roll.