Section 8 Additional requirements

8.1.1 The main steering gear is to comprise two or more identical power units complying with provisions of Pt 5, Ch 19, 2.2 Performance requirements for rudder-type steering systems 2.2.3.

8.2.1 Subject to Pt 5, Ch 19, 8.3 For tankers, chemical tankers or gas carriers of 10 000 tons gross and upwards but of less than 100 000 tons deadweight the following are to be complied with:

1. The main steering gear is to 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 is to be regained in not more than 45 seconds after the loss of one power actuating system.

2. The main steering gear is to comprise either:

   1. two independent and separate power actuating systems, each capable of meeting the requirements of Pt 5, Ch 19, 2.2 Performance requirements for rudder-type steering systems 2.2.1.(a); or

   2. at least two identical power actuating systems which, acting simultaneously in normal operation, are capable of meeting the requirements of Pt 5, Ch 19, 2.2 Performance requirements for rudder-type steering systems 2.2.1.(a). Where necessary to comply with these requirements, inter-connection of hydraulic power actuating systems is to be provided. Loss of hydraulic fluid from one system is to be capable of being detected and the defective system automatically isolated so that the other actuating system or systems remain fully operational.

3. Steering gears other than of the hydraulic type are to achieve equivalent Standards.

8.3.1 Solutions other than those set out in Pt 5, Ch 19, 8.2 For tankers, chemical tankers or gas carriers of 10 000 tons gross and upwards 8.2.1 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:

1. 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

2. 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, the material used, the installation of sealing arrangements and the testing and inspection and provision of effective maintenance. In consideration of the foregoing, regard will be given to the `Guidelines' in Pt 5, Ch 19, 9 'Guidelines' for the acceptance of non-duplicated rudder actuators for tankers, chemical tankers and gas carriers of 10 000 tons gross and upwards but of less than 100 000 tons deadweight.

8.3.2 Manufacturers of steering gear who intend their product to comply with the requirements of the `Guidelines' are to submit full details when plans are forwarded for approval.