| 1 | A steering gear compartment shall(a) be readily accessible; (b) as far as practicable, be separated from propulsion machinery and auxiliary machinery spaces; and (c) be equipped with a means of communication with the bridge.
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| 2 | All components and, in particular, non-duplicated essential components, shall be of sound and reliable construction, of adequate strength and protected against shock loading. |
| 3 | For essential components, bearings that are permanently lubricated or provided with lubrication fittings shall be utilized where required for the safe operation of the ship. |
| 4 | The pressure of the fluid for calculations to determine the scantlings of piping and steering gear components subjected to internal hydraulic pressure shall be at least 1.25 times the design working pressure under the operating conditions set out in item 9, taking into account any pressure that may exist in the low-pressure side of the system. |
| 5 | Where, due to dynamic loads on piping and steering gear components, pulsating pressures occur, the system design shall be such that fatigue does not cause material failure. |
| 6 | Relief valves shall be fitted to any part of the hydraulic system that can be isolated and in which pressure can be generated from the power source or from external forces. |
| 7 | Relief valve settings shall not exceed the design working pressure of the fluid set out in item 4 and the valves shall be of adequate size and arranged to avoid an undue rise in pressure above the design working pressure of the fluid. |
| Steering Gears |
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| 8 | Subject to items 19 and 20, the installation shall consist of totally independent main and auxiliary steering gears. |
| 9 | The main steering gear shall be designed, where the ship is at its deepest sea-going draft and(a) running ahead at maximum service speed, to put the rudder over (i) from 35 degrees on one side to 35 degrees on the other side, and (ii) from 35 degrees on either side to 30 degrees on the other side in not more than 28 seconds; and
(b) running astern at maximum speed, for maximum rudder angle operation.
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| 10 | A main steering gear shall be power-operated(a) where necessary to meet the requirements of item 9; and (b) where a rudder stock of over 120 mm in diameter, excluding strengthening for navigation in ice, is required at the position of tiller attachment.
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| 11 | The auxiliary steering gear shall be designed, where the ship is at its deepest sea-going draft and running ahead one-half its maximum service speed or 7 knots, whichever is the greater, to put the rudder over from 15 degrees on one side to 15 degrees on the other side in not more than 60 seconds. |
| 12 | The auxiliary steering gear shall have the capacity to be brought safely and rapidly into action in an emergency. |
| 13 | An auxiliary steering gear shall be power-operated(a) where necessary to meet the requirements of item 11; and (b) where a rudder stock of over 230 mm in diameter, excluding strengthening for navigation in ice, is required at the position of tiller attachment.
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| 14 | A power-operated auxiliary steering gear unit and its associated control system and rudder angle indicator shall, where the rudder stock is required to be over 230 mm in diameter, excluding strengthening for navigation in ice, be provided automatically with an alternative power source within 45 seconds of the failure of the main power source, from |
| 15 | The alternative power source referred to in item 14 shall(a) in any ship of 10,000 tons gross tonnage or more be capable of at least 30 minutes continuous operation; and (b) in any other ship, be capable of at least 10 minutes continuous operation.
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| 16 | Main and auxiliary steering gear power units shall be (a) capable of being brought into operation from a location on the bridge; (b) arranged to start automatically where power is restored after a power failure; and (c) equipped with an audible and visual alarm located on the bridge to indicate a power failure to any one power unit.
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| 17 | Hydraulic power-operated main and auxiliary steering gears shall be equipped with the following: (a) arrangements to maintain the cleanliness of the hydraulic fluid, taking into consideration the type and design of the hydraulic system; (b) an audible and visual low-fluid-level alarm for each hydraulic fluid reservoir to give the bridge and the propulsion machinery space the earliest possible indication of hydraulic fluid leakage; (c) a fixed storage tank that has a contents gauge and sufficient capacity to refill the contents of at least one power-actuating system, including the reservoir, where the main steering gear is required to be power-operated; and (d) means by which the hydraulic systems can be readily and rapidly refilled from within the steering gear compartment through permanently connected piping leading from the storage tank.
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| 18 | Electric and electrohydraulic power-operated main and auxiliary steering gears shall meet the following requirements:(a) means for indicating whether the motors of the electric or electrohydraulic steering gears are running shall be installed on the bridge and at a suitable propulsion machinery control location; (b) each electric or electrohydraulic steering gear comprising one or more power units shall be served by at least two exclusive circuits fed directly from the main switchboard, where one of the circuits may be supplied through the emergency switchboard; (c) an electric or electrohydraulic auxiliary steering gear associated with an electric or electrohydraulic main steering gear may be connected to one of the circuits supplying the main steering gear if the circuits have adequate rating for supplying all motors that can be simultaneously connected to them and that may be required to operate simultaneously; (d) short-circuit protection and an overload alarm shall be provided for the circuits and motors, and where protection against excess current including starting current is provided for a circuit or motor, the protection shall be not less than twice the full load current of the circuit or motor, as the case may be and shall be arranged to permit the passage of the appropriate starting currents; (e) where a three-phase power supply is used, an alarm shall be provided to indicate failure of any one of the supply phases and the alarm shall be audible, visual and situated (i) in a conspicuous location in the main machinery space or control room from which the main machinery is normally controlled, and (ii) as may be required by Schedule VIII;
(f) where an auxiliary steering gear that is in a ship of less than 1,600 tons gross tonnage and that is required to be power-operated is not electrically powered or is powered by an electric motor primarily intended for other services, the main steering gear may be fed by one circuit from the main switchboard; and (g) where an electric motor primarily intended for other services is arranged to power an auxiliary steering gear in a ship of less than 1,600 tons gross tonnage, protection arrangements for electric and electrohydraulic power-operated steering gears are not required to meet the requirements set out in paragraphs (d) and (e) if suitable alternative arrangements are made.
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| 19 | An auxiliary steering gear is not required where main steering gear power units and connections are fitted in duplicate if (a) for ships carrying more than 12 passengers, each steering gear power unit enables the steering gear to meet the requirements of item 9; (b) for ships carrying not more than 12 passengers, both steering gear power units operating together enable the steering gear to meet the requirements of item 9; and (c) for hydraulic-type steering gears, the main steering gear is arranged so that, after a single failure in its piping or in one of the steering gear power units, the defect can be isolated and steering capability can be maintained or rapidly regained, and for other types of steering gear, a similar standard can be achieved.
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| 20 | An auxiliary steering gear is not required for double-ended ships with two independent steering systems, one fore and one aft, if in the case of failure of one of the steering systems the corresponding rudder can be safely and rapidly brought back to the centre line and kept steady in that position. |
| 21 | For every tanker, chemical tanker or gas carrier of 10,000 tons gross tonnage or more and every other ship of 70,000 tons gross tonnage or more, the main steering gear shall comprise two or more identical power units that meet the requirements of item 19. |
| 22 | Subject to item 23, every tanker, chemical tanker or gas carrier of 10,000 tons gross tonnage or more shall meet the following requirements: (a) the main steering gear shall be so arranged that in the event of loss of steering capability due to a single failure in any part of one of the power-actuating systems of the main steering gear, excluding the tiller, quadrant or components serving the same purpose or a seizure of the rudder actuators, steering capability shall be regained in less than 45 seconds after the loss of one power actuating system; (b) the main steering gear shall comprise (i) two independent and separate power-actuating systems, each capable of meeting the requirements of item 9, or (ii) at least two identical power-actuating systems that, acting simultaneously in normal operation, shall be capable of meeting the requirements of item 9 if (A) interconnection of hydraulic power-actuating systems, where necessary, is provided, and (B) loss of hydraulic fluid from one of the systems is capable of being detected and that system is automatically isolated so that the other system or systems remain fully operational; and
(c) steering gears, other than of the hydraulic type, shall achieve a standard equivalent to the standard referred to in subitem (b).
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| 23 | For tankers, chemical tankers or gas carriers of 10,000 tons gross tonnage or more, but of less than 100,000 tonnes deadweight, in the event of a single failure referred to in item 22 of a rudder actuator, the requirements set out in that item are not required to be met if(a) a safety standard equivalent to the standard set out in item 22 is achieved; (b) components meet the requirements of item 1 of Division II; (c) following loss of steering capability due to a single failure of any part of the piping system or in one of the power units, steering capability is regained within 45 seconds; and (d) where the steering gear includes only a single rudder actuator, the following factors are taken into special consideration in the actuator design and construction: (i) stress analyses including, as appropriate, fatigue analysis and fracture mechanics analysis, (ii) materials used, and (iii) hydraulic fluid sealing arrangements.
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