Controlling Ship's Speed and Direction from Bridge
Every ship should have an indicator for the propeller speed and direction of rotation on the bridge. If the propeller is of controllable pitch, there should be indication of pitch also. On UMS ships, machinery can be controlled from the bridge.
In Integrated Bridge System (IBS), various operations such as passage execution, communications, machinery control, and safety and security are centrally monitored. Engines can be stopped in emergency. Overriding provisions are made in case of main engine.
A telegraph is provided on the bridge for communication with the engine room regarding engine speed and direction. Controls are tested before departure and the engine movements are recorded in bridge. The bridge telegraph may be connected to a teleprinter for automatic recording. Repeaters are provided on the bridge wings.
The speed log shows the ship’s speed in knots, and the distance indicator records distance covered in nautical miles. A calibration chart is provided; these readings should be verified by plotting the ship’s position on the charts.
The ship’s direction is set by the use of the Standard Magnetic Compass, Steering Magnetic Compass, or Gyrocompass. There should be communication between the standard magnetic compass and the steering position. An efficient periscope with sufficient magnification and adjustability is provided for comfortable viewing of the standard compass by the helmsman. The steering compass must be compared with the standard compass at least once per watch and after every major alteration of course. Deviations are recorded on a card maintained on the bridge. The standard compass should be checked and adjusted when the deviation shows a marked change.
The gyrocompass repeater is fitted at each steering position. An autopilot, set manually, maintains the ship’s course until a new course is entered. When likened to IBS, it can correct cross track errors and automatically keep the ship on the planned track. An off-course alarm is also fitted.
Steering may be manually controlled from the bridge. The steering wheel operates the telemotor transmitter. Rudder angle indicators are fitted at the steering positions. Repeaters are fitted in bridge wing. While testing controls, the rudder angle indicator must be compared with the actual rudder angle.