Hotel Service Unit 16 Stabilizer Q4 Answer

Describe, with the aid of a sketch, the construction and operation of an Active Controlled Tank roll damping system.(10)

Two wing tanks (port and starboard) are fitted at the top of the ship, connected by a cross-duct.
A central control tank or header tank is located amidships.
Butterfly valves / throttling valves are fitted in the cross-duct and controlled automatically.
Pumps may assist water transfer in some designs, but many systems rely on gravity and roll inertia.
A control system (gyro sensor + feedback unit) monitors vessel roll motion and adjusts valve openings accordingly.

When the vessel rolls, water in the active tank system is made to move out of phase with the ship’s roll.
The control valves open and close in response to roll angle and velocity, as detected by the gyro.
Water shifts between the port and starboard tanks, creating a counter-moment to oppose roll.
This damps roll amplitude significantly compared with passive tanks, since flow is actively regulated.
The system can be tuned to different sea states and vessel speeds, providing greater efficiency than a passive free-surface tank.