1 Scope
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1398 – Unified Interpretation of SOLAS Regulation II-2/29 – (10 June 2011) - Annex – Mechanical, Hydraulic and Electrical Independency and Failure Detection and Response of Steering Control Systems - 1 Scope

1 Scope

 The interpretation applies to steering gear control systems, as defined in SOLAS regulation II-1/3.1, for the main and auxiliary steering gear, operable from the navigation bridge, for which SOLAS stipulates two steering gear control systems independent of each other (SOLAS chapter II-1, regulations 29.6.1, 29.7.2, 29.7.3, 29.15 and 29.16).

 SOLAS chapter II-1, regulation 29.6.1, reads:

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

    • .1 in a passenger ship, the main steering gear is capable of operating the rudder as required by paragraph 3.2 while any one of the power units is out of operation;

    • .2 in a cargo ship, the main steering gear is capable of operating the rudder as required by paragraph 3.2 while operating with all power units; and

    • .3 the main steering gear is so arranged that after a single failure in its piping system or in one of the power units the defect can be isolated so that steering capability can be maintained or speedily regained."

 SOLAS chapter II-1, regulations 29.7.2 and 7.3, read:

  • "7 Steering gear control shall be provided:

    • .2 where the main steering gear is arranged in accordance with paragraph 6, by two independent control systems, both operable from the navigation bridge. This does not require duplication of the steering wheel or steering lever. Where the control system consists of a hydraulic telemotor, a second independent system need not be fitted, except in a tanker, chemical tanker or gas carrier of 10,000 gross tonnage and upwards; and

    • .3 for the auxiliary steering gear, in the steering gear compartment and, if power-operated, it shall also be operable from the navigation bridge and shall be independent of the control system for the main steering gear."

 SOLAS chapter II-1, regulations 29.15 and 16, read:

  • "15 In every tanker, chemical tanker or gas carrier of 10,000 gross tonnage and upwards and in every other ship of 70,000 gross tonnage and upwards, the main steering gear shall comprise two or more identical power units complying with the provisions of paragraph 6.

  • 16 Every tanker, chemical tanker or gas carrier of 10,000 gross tonnage and upwards shall, subject to paragraph 17, comply with the following:

    • .1 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 seizure of the rudder actuators, steering capability shall be regained in not more than 45 s after the loss of one power actuating system;

    • .2 the main steering gear shall comprise either:

      • .2.1 two independent and separate power actuating systems, each capable of meeting the requirements of paragraph 3.2; or

      • .2.2 at least two identical power actuating systems which, acting simultaneously in normal operation, shall be capable of meeting the requirements of paragraph 3.2. 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 automatically isolated so that the other actuating system or systems shall remain fully operational;

    • .3 steering gears other than of the hydraulic type shall achieve equivalent standards."

 The requirements of SOLAS chapter II-1, regulations 3.1, 3.3, 3.13 and 29 have been considered, as far as containing requirements for the independency of the control systems.

Parent topic: Annex – Mechanical, Hydraulic and Electrical Independency and Failure Detection and Response of Steering Control Systems
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