Antiroll Tanks

A roll tank is a water-filled tank in the hull of a ship, the fluctuations around the longitudinal axis to (called roles) dampen.

The rolling tank was invented by Dr. Hermann Frahm and installed in accordance with the first in 1889 carried out on the ship City of New York trials in 1912 for the first time in the steamer Laconia fixed. The system is in principle a water pendulum, which is tuned to the natural resonance of the vessel. It consists of two mounted on the longitudinal sides of the ship tanks, which are as high as possible, and connected to pipes.

Rain sideways impinging waves the ship to roll in is moved at resonance the phase of ship vibration at 90 ° to that of the shock waves. The rolling ship can now in turn the ballast water between the two tanks back and sloshing. If the natural frequency of this pendulum water (adjustable amount of water and the pipe cross-section) corresponds to the natural frequency of the vessel, there is a further phase shift of 90 °. Total follows that the phases of the incident waves and the side tank water vibration are shifted by 180 °. This anti-phase movement attenuates largely rolling movement of the vessel about the longitudinal axis.

Source

• Development of ship stabilizers ( English)
• Investigation on the effect of rolling tanks