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- Helm Unit. Mechanical device used to steer the ship. Helm consists of:
- Wheel. The ship’s wheel is on the steering control console and has controls and indicators required to control the course of the ship. The ship is steered by the helmsman.
- Mechanical Helm Indicator. Indicates the number of degrees the wheel is turned. Usually this is the same number of degree as the rudder’s position.
- Rudder Angle Indicator. It has a dual purpose. During normal steering situations, it shows the actual angle of the rudder which usually lags the wheel angle indicator by about 2 degrees because of the time required for the steering mechanism to operate. For emergency steering, this instrument becomes useful in transmitting visual orders to the helmsman who is located in the after-steering compartment. By operation of the control knob, the rudder order is displayed on the instrument when the pointer marked "ORD" is moved to the desired rudder angle. The order is displayed in after-steering on another rudder angle order indicator-transmitter, from which the after helmsman receives orders. A push switch next to the rudder angle order indicator-transmitter on the bridge operates a bell in after-steering to call the helmsman's attention to a change in rudder angle.
- "Steer by" Indicator. It displays the course to be steered by the helmsman. It differs mainly from the ship's course indicator in that its dials are positioned from a synchro transmitter located in sonar, CIC, or other Weapons Control Station, which allows these stations to to steer without having to use a means of voice transmission.