A FLUME® roll damping system is a passive free surface open channel type anti-roll tank. It has the unique ability to adapt to changes in load and operation conditions. By a simple change in the liquid level, the natural response period of the tank can be adjusted to the roll period of the ship. However, obtaining and maintaining the correct operational condition of the stabilizer is difficult at sea due to the constant and turbulent movement of the liquid within the tank. FLUME® has developed the Liquid Level & Roll Period Indicating System and the Phase Sensing System to monitor the movement and control the anti-roll tank to assist the crew in achieving the most effective roll stabilization.
Liquid Level & Roll Period Indication System
The Liquid Level & Roll Period Indicating System has been developed to provide fast and reliable information on the operational condition of the stabilizer. Pressure sensors are used to constantly measure the liquid level inside the tank. The actual roll period of the ship, which is the critical basis for deciding the proper level is acquired with Hoppe's inertial measuring system HOSIM. The display unit HOMIP which is intended for console mounting on the bridge is a computer based 6” touch screen that averages and displays long term values of the level and the roll period. A liquid level bar graph that is based on model tests of the stabilizer tank is shown on the control unit display to indicate the correct liquid level that should be used for the measured roll period.
Phase Sensing System
This is a more sophisticated monitoring & control system. It measures the phase lag between the roll motion of the ship and the fluid flow within the stabilizer to ensure that it is approximately 90 degrees. If the level is too low or too high, the phase difference is greater or less, respectively. The system signals the crew optimum operational conditions to allow the stabilizer to work at its peak performance. Liquid level can also be controlled automatically with a designated pump as an option.
Fast Discharge System
In an emergency situation, it might be necessary to quickly increase the transverse metacentric height to improve the stability of the vessel. FLUME® has developed the Fast Discharge System, operated via remote valves, to dump the amount of liquid directly overboard. Hence, weight and free surface effect of the stabilizer on the tmetacentric height is immediately eliminated