Section 5 Steering

501. General

1. Except as provided in Par 2, units are to be provided with a main steering gear and an auxiliary steering gear to the satisfaction of the Society. The main steering gear and the auxiliary steering gear are to be so arranged that a single failure in one of them so far as is reasonable and practi- cable will not render the other one inoperative.

2. Where a non-conventional rudder is installed, or where a unit is steered by means other than a rudder, the Society is to give special consideration to the steering system so as to ensure that an acceptable degree of reliability and effectiveness, which is based on Par 1, is provided.

502. Performance of main steering gear

1. The main steering gear is to be of adequate strength and sufficient to steer the unit at maximum service speed and this should be demonstrated. The main steering gear and rudder stock are to be so designed that they will not be damaged at maximum astern speed but this design requirement need not be proved by trials at maximum astern speed and maximum rudder angle.

2. The main steering gear is to, with the unit at its deepest seagoing draught, be capable of putting the rudder over from 35° on one side to 35° on the other side with the unit running ahead at maximum service speed. The rudder is to be capable of being put over from 35° on either side to 30° on the other side in not more than 28 s, under the same conditions.

3. The main steering gear is to be operated by power where necessary to fulfil the provisions of Par 2 and in any case in which the Society would require a rudder stock of over 120 mm diameter in way of the tiller.

4. The main steering gear power unit or units are to be arranged to start automatically when power is

restored after a power failure.

503. Performance of auxiliary steering gear

1. The auxiliary steering gear is to

be of adequate strength and sufficient to steer the unit at navi-

gable speed and capable of being brought speedily into action in an emergency.

2. The auxiliary steering gear is to

be capable of putting the rudder over from 15° on one side to

15° on the other side in not more than 60 seconds with the unit at its deepest seagoing draught while running at one half of its maximum speed ahead or seven knots, whichever is the greater.

3. The auxiliary steering gear is to be operated by power where necessary to fulfil the provisions of Par 1 and in any case in which the Society would require a rudder stock of over 230 mm diame- ter in way of the tiller.

504. Number of steering gears

Where the main steering gear comprises two or more identical power units, the auxiliary steering gear need not be fitted provided that:

(1) The main steering gear is capable of operating the rudder in accordance with the provisions of

502. 2 while operating with all power units.

(2) As far as is reasonable and practicable the main steering gear is to be so arranged that a single failure in its piping or in one of the power units will not impair the integrity of the remaining part of the steering gear.

505. Controls

1. Control of the main steering gear is to be provided both on the navigating bridge and in the steer- ing gear compartment. If the steering gear control system which provides for control from the navi- gating bridge is electric, it is to be supplied from the steering gear power circuit from a point within the steering gear compartment.

2. When the main steering gear is arranged according to 504., two independent control systems are to be provided, each of which can be operated from the navigating bridge. Where the control system comprises a hydraulic telemeter, the Society may waive the provisions for a second independent control system.

3. Where the auxiliary steering gear is power operated, it is to be provided with a control system op- erated from the navigating bridge and this is to be independent of the control system for the main steering gear.

4. Means are to be provided in the steering gear compartment to disconnect the steering gear control system from the power circuit.

5. A means of communication is to be provided between the navigating bridge and:

(1) the steering gear compartment;and

(2) the emergency steering position, if provided.

6. The exact angular position of the rudder, if power operated, is to be indicated on the navigating bridge. The rudder angle indication is to be independent of the steering gear control system.

7. The angular position of the rudder is to be recognizable in the steering gear compartment.

8. An alternative power supply, sufficient at least to supply a steering gear power unit which complies with the provisions of 503. 2 and also its associated control system and the rudder angle indicator, is to be provided, automatically, within 45 s, either from the emergency source of electrical power or from another independent source of power located in the steering gear compartment. This in- dependent source of power is to be used only for this purpose and is to have a capacity sufficient for 10 min of continuous operation.

506. Electric and electro-hydraulic steering gear

1. Indicators for running indication of the motors of electric and electro-hydraulic steering gear are to be installed on the navigating bridge and at a suitable machinery control position.

2. Each electric or electro-hydraulic steering gear comprising one or more power units is to be served by at least two circuits fed from the main switchboard. One of the circuits may pass through the emergency switchboard. An auxiliary electric or electrohydraulic steering gear associated with a main electric or electrohydraulic steering gear may be connected to one of the circuits supplying

this main steering gear. The circuits supplying have adequate rating for supplying all motors have to operate simultaneously.

3. Short-circuit protection and an overload alarm

an electric or electrohydraulic steering gear are to which can be simultaneously connected to it and

should be provided for these circuits and motors.

Protection against excess current, if provided, is to be for not less than twice the full load current of the motor or circuit so protected, and is to be arranged to permit the passage of the appropriate

starting currents. Where a three-phase supply is used, an alarm is to be provided that will indicate failure of any one of the supply phases. The alarms required herein is to be both audible and visu-

al and be situated in a position on the navigating bridge where they can be readily observed.