An emergency steering system, as the name suggests, is used during the failure of the main steering system of the ship.
What is Emergency steering?
A ship consists of electromechanical steering gear unit, which steers the vessel from one port to other. Normally steering gear unit is 2 or 4 ram electro-hydraulically operated unit with two or more hydraulic motors for the ram movement.
A situation can occur in which the remote control operation may fail to work and there can be loss of steering control from the bridge. This can be due to sudden power failure or electrical fault in the system or the control system, which includes faulty tele-motor or servomotor used for transferring the signal from bridge to the steering unit.
To manually control the steering of the ship in such emergency situations from within the steering gear room, an emergency steering system is used.
Procedure for Emergency Steering Operation
The following points should be followed for emergency steering operation:
The procedure and diagram for operating emergency steering should be displayed in steering gear room and bridge Even in emergency situation we cannot turn the massive rudder by hand or any other means, and that's why a hydraulic motor is given a supply from the emergency generator directly through emergency switchboard (SOLAS regulation). This should also be displayed in the steering room Ensure a clear communication for emergency operation via VHF or ship's telephone system Normally a switch is given in the power supply panel of steering gear for tele-motor; switch off the supply from the panel Change the mode of operation by selecting the switch for the motor, to which emergency power is supplied There is a safety pin at the manual operation helms wheel so that during normal operation the manual operation always remains in cut-off mode. Remove that pin A helms wheel to control the flow of oil to the rams is provided with a rudder angle indicator. Wheel can be turned clockwise or anti-clockwise for going port or starboard or vice versa If there is a power failure, use telephone to receive orders from the bridge for the rudder angle. As soon as you get the orders, turn the wheel and check the rudder angle indicator A routine check should always be done for proper working of manual emergency system and steering gear system. An emergency steering drill should be carried out every month (prescribed duration - 3 months) in the steering gear room with proper communication with the bridge in order to train all the ship's staff for smooth operation of the system, so that in emergency situation ship's control can be regained as soon as possible, avoiding collision or grounding
References
A Pocket Guide To Fixed Fire Fighting Systems and Emergency Procedures For Ship’s Engine Room (Author: Marine Insight)