Section 79

capable of putting the rudder over from 35° on one side to 35° on the other side with the ship at its deepest seagoing draught and running ahead at maximum ahead service speed and, under the same conditions, from 35° on either side to 30° on the other side in not more than 28

seconds;

operated by power where necessary to meet the requirement of paragraph {b) and in any case, when the Director requires a rudder stock of over 120 millimetres diameter in way of the tiller, excluding strengthening for navigation in ice; and

{d)

so designed that they will not be gamaged at maximum astern speed; however, this design requirement need not be proved by trials at maximum astern speed and maximum rudder angle.

(4}

The auxiliary steering gear shall be-

{a) of adequate strength and capable of steering the ship at navigable speed and of being brought speedily into action in an emergency;

{b)

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 ship at its deepest seagoing draught and running ahead at one-half of the maximum ahead service speed or 7 knots, whichever is the greater; and

{c) operated by power where necessary to meet the requirements of paragraph {b) and in any case when the Director requires a rudder stock of over 230 millimetres diameter in way of the tiller, excluding strengthening for navigation in ice.

{5)

Main and auxiliary steering gear power units shall be-

{a)

arranged to re-start automatically when power is restored after a power failure; and

{b)

capable of being brought into operation from a position on the navigation bridge. In the event of a power failure to any one of the steering gear power units, an audible and visual alarm shall be given on the naviga-tion bridge.

{a) Where the main steering gear comprises 2 or more identical power units, an auxiliary steering gear need not be fitted, provided that -

Steering gear control shall be provided -

{a)

for the main steering gear, both on the navigation bridge and in the steering gear compartment;

Any main and auxiliary steering gear control system operable from the navigation bridge shall comply with the following -

{a)

if electric, it shall be served by its own separate circuit supplied from a steering gear power circuit from a point within the steering gear compartment, or directly from switchboard busbars supplying that steering gear power circuit at a point on the switchboard adjacent to the supply to the steering gear power circuit;

The electrical power circuits and the steering gear control systems with their associated components, cables and pipes required by this regulation and regulation 80 shall be separated as far as is practicable throughout their length.

!10)

A means of communication shall be provided between the navigation bridge and the steering gear compartment.

The angular position of the rudder shall-

{a}

if the main steering gear is power-operated, be indicated on the navigation bridge. The rudder angle indication shall be independent of the steering gear control system; and fb}

be recognisable in the steering gear compartment.

( 12)

Hydraulic power-operated steering gear shall be provided with the following-

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{a}

arrangements to maintain the cleanliness of the hydraulic fluid taking into consideration the type and design of the hydraulic system;

{b}

a low level alarm for each hydraulic fluid reservoir to give the earliest practicable indication of hydraulic fluid leakage. Audible and visual alarms shall be given on the navigation bridge and in the machinery space where they can be readily observed; and

{c} a fixed storage tank having sufficient capacity to recharge at least one power actuating system including the reservoir, where the main steering gear is required to be power operated. The storage tank shall be permanently connected by piping in such a manner that the hydraulic systems can be readily recharged from a position within the steering gear compartment and shall be provided with a contents gauge.

The steering gear compartments shall be-

{a)

readily accessible and, as far as practicable, separated from machinery spaces; and

{b)

provided with suitable arrangements to ensure working access to steering gear machinery and controls. These arrangements shall include handrails and gratings or other non-slip surfaces to ensure suitable working conditions in the event of hydraulic fluid leakage.

Where the rudder stock is required to be over 230 millimetres diameter in way of the tiller, excluding strengthening for navigation in ice, an alternative power supply, sufficient at least to supply the steering gear power unit which complies with the requirements of paragraph (b) of sub-regulation (4) and also its associated control system and the rudder angle indicator, shall be provided automatically, within 45 seconds, either from the emergency source of electrical power or from an independent source of power located in the steering gear compartment. This independent source of power shall be used only for this purpose. In every ship of 10,000 tons and upwards, the alternative power supply shall have a capacity for at least 30 minutes of continuous operation and in any other ship for at least 10 minutes.

In every tanker/ chemical tanker or gas carrier of 10 1000 tons and upwards and in every other ship of 70 1000 tons and upwards1 the main steering gear shall comprise 2 or more identical power units complying with the provisions of sub-regulation (6).

( 16)

Every tanker/ chemical tanker or gas carrier of 10,000 tons and upwards shall, subject to sub-regulation (17), comply with the following-

{a} the main steering 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 seizure of the rudder actuators, steering capability shall be regained in not more than 45 seconds after the loss of one power actuating system;

{b)

the main steering gear shall comprise either-

. Where necessary to comply with this requirement, interconnection of hydraulic power actuating systems shall be provided. Loss of hydraulic fluid from one system shall be capable of being detected and the defective system auto-matically isolated so that the other actuating system or systems shall remain fully operational;

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{c} steering gears other than of the hydraulic type shall achieve equivalent standards.

For tankers, chemical tankers or gas carriers of 10,000 tons and upwards, but of less than 100,000 tons deadweight, solutions other than those set out in sub-regulation (16), which need not apply the single failure criterion to the rudder actuator or actuators, may be permitted provided that an equivalent safety standard is achieved and that

{a} 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 shall be regained within 45 seconds; and

{b} where the steering gear includes only a single rudder actuator, special consideration is given to stress analysis for the design, including fatigue analysis and fracture mechanics analysis, as appropriate, to the material used, to the installation of sealing arrangements and to testing and inspection and to the provision of effective maintenance. The provisions of the Guidelines for Acceptance of Non-Duplicated Rudder Actuators for

Tankers, Chemical Tankers and Gas Carriers of 10,000 tons and above but less than 100,000 tons deadweight, adopted by the Organisation shall also be applied.*

Every tanker, chemical tanker or gas carrier of 10,000 tons and upwards, constructed before 1st. September, 1984, shall comply with the following-

{a}

the requirements of paragraph {a} of sub-regulation (7), paragraphs

(b} and {d} of sub-regulation (8), sub-regulations (10), (11), paragraphs (b} and

{c} of sub-regulation (12) and paragraph {b} of sub-regulation (13);

{b}

2 independent steering gear control systems shall be provided, each of which can be operated from the navigation bridge. This does not require duplication of the steering wheel or steering lever;

{c}

if the steering gear control system in operation fails, the second system shall be capable of being brought into immediate operation from the navigation bridge; and

{d} each steering gear control system, if electric, shall be served by its own separate circuit supplied from the steering gear power circuit or directly from switchboard busbars supplying that steering gear power circuit at a point on the switchboard adjacent to the supply to the steering gear power circuit.

* Adopted by the Organisation by resolution A.467(XII).

In addition to the requirements of sub-regulation (18), in every tanker, chemical tanker or gas carrier of 40,000 tons and upwards, constructed before 1st. September, 1984, the steering gear shall be so arranged that, in the event of a single failure of the piping or of one of the power units, steering capability can be maintained or the rudder movement can be limited so that steering capability can be speedily regained. This shall be achieved by fa} an independent means of restraining the rudder;

{b)

fast acting valves which may be manually operated to isolate the actuator or actuators from the external hydraulic piping, together with a means of directly refilling the actuators by a fixed independent power-operated pump and piping system; or

{c) an arrangement such that, where hydraulic power systems are interconnected, loss of hydraulic fluid from one system shall be detected and the defective system isolated either automatically or from the naviga-tion bridge so that the other system remains fully operational.

Additional requirements for electric and electro hydraulic steering gear.