SOLAS Requirement on steering gear system
- One of the critical equipment on-board! But I don’t know why most of us, especially junior engineers tend to pay very less attention to steering gear! I just recollect my days as cadet, 4th and 3rd Engineer. Yes we did pay required attention but not as much we would do to a Main / Aux engine, Boiler, Purifier and most of the engine room equipment…..May be due to 2 reasons….1. It is outside engine room. 2. Mostly they do not create much trouble and when they do we are in real trouble.
- Well now all of us are in same page trying to learn about steering gear be it for your knowledge or for exam preparation I will try to cover as much is required to attend all the aspects.
- Remember this article covers mainly the statutory requirements otherwise minimum required standards which every ship’s steering gear should follow.
>> SOLAS 74/78, Chapter II-1 – which is Construction – Structure, subdivision and stability, machinery and electrical installations, in Part C – which is Machinery installations- through Regulation 29 – Steering gear provides the statutory requirements for the steering gears.
>> However, Later the same was modified and adopted through RESOLUTION A.415(XI), which was adopted on 15 November 1979 provides IMPROVED STEERING GFAR STANDARDS FOR PASSENGER AND CARGO SHIPS.
>> Similarly, RESOLUTION A.416(XI) adopted on 15 November 1979 provides regulations for EXAMINATION OF STEERING GEARS ON EXISTING TANKERS.
SOLAS Requirement on steering gear system
- Unless expressly provided otherwise, every ship shall be provided with a main steering gear and an auxiliary steering gear to the satisfaction of the Administration. The main steering gear and the auxiliary steering gear shall be so arranged that the failure of one of them will not render the other one inoperative.
- Shall be 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 s;
- Shall be capable of putting the rudder over from 15° on one side to 15° on the other side in not more than 60 s 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;
- Well yes, Not necessarily all ships should have both main and auxiliary steering gear. Let’s see what the actual requirement is!
- In every tanker, chemical tanker or gas carrier of 10,000 gross tonnage and upwards-AND-
- Every other ship of 70,000 gross tonnage and upwards, the main steering gear shall comprise two or more identical power
- Where the main steering gear comprises TWO OR MORE IDENTICAL POWER UNITS, an auxiliary steering gear need not be fitted. Ofcourse there are some conditions to be satisfied which are.
- In a passenger ship, the main steering gear is capable of operating the rudder as required by operating conditions while any one of the power units is out of operation.
Meaning in passenger ship each steering unit shall have 100% redundancy.
- In a cargo ship, the main steering gear is capable of operating the rudder as required by operating conditions while operating with all power units.
Meaning in cargo ship each steering unit shall have 50% redundancy.
- Third requirement is nothing but a safematic system where, 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.
None of the ships I sailed had an Auxiliary steering gear, I spoke to my friend who is a senior chief engineer, He did mention that he hasn’t seen an auxiliary steering gear. All we have seen is 2 identical units with 100% redundancy. It does make some sense! Why install a lower powered steering gear for a slightly lower price when we can have 2 identical units for a very small price difference.
- The design pressure for calculations to determine the scantlings of piping and other steering gear components subjected to internal hydraulic pressure shall be at least 1.25 times the maximum working pressure to be expected under the operational conditions specified.
- Control shall be provided for the main steering gear, both on the navigation bridge and in the steering gear compartment.
- Similarly, for the auxiliary steering gear as well there shall be control from both locations independent of each other.
- Irrespective of either main or auxiliary steering gear, the control system operable from the navigation bridge shall comply with the following requirements.
- If electric, should be fed from 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….That also, at a point on the switchboard adjacent to the supply to the steering gear power circuit;
- Means shall be provided in the steering gear compartment for disconnecting bridge control.
- The system should be able to be started from bridge.
- Alarm both visual & audible in case of a power failure in bridge.
- Short circuit protection is allowed only for control system.
- The electrical power circuits and the steering gear control systems, cables and pipes shall be separated as far as is practicable throughout their length.
- A means of communication shall be provided between the navigation bridge and the steering gear compartment.
- Arrangements to maintain the cleanliness of the hydraulic fluid shall be provided.
- Low-level alarm for each reservoir for early indication of hydraulic fluid leakage. Audible and visual alarms shall be given on the navigation bridge and ECR.
- A fixed storage tank with level indicator having sufficient capacity to recharge at least one power actuating system including the reservoir. The storage tank shall be permanently connected by piping so that the hydraulic systems can be readily recharged.
- 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.
- Be recognizable in the steering gear compartment. – Obviously!
As junior engineering officer, I have always wondered why is steering gear so inaccessible from engine room?? Well, I am talking about passenger ships – Even in cargo ships it is not readily accessible you have to climb few floors and move aft to get access to steering gear compartment.
But thoughtlessly rudder is one of the aft most equipment so steering gear has to be in the aft, plus the following points explain further. Let us see the statutory requirements.
- The steering gear compartments shall be;
- Readily accessible and, as far as practicable, separated from machinery spaces;
- Provided with suitable arrangements to ensure working access to steering gear machinery and controls.
- These arrangements shall include handrails and gratings or other nonslip surfaces to ensure suitable working conditions in the event of hydraulic fluid leakage.
- Where the rudder stock is required to be over 230 mm diameter in way of the tiller, excluding strengthening for navigation in ice, an alternative power supply should be available.
- This power shall be able to supply at least the Auxiliary steering gear and its requirements as mentioned above. If your ship doesn’t have an Auxiliary steering gear, then one of the 2 steering gears should be supplied by the emergency supply.
- Not only the steering power but also provide power to its associated control system and the rudder angle indicator.
- All of the above mentioned item should be supplied 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.
For how long emergency power should supply??
- In every ship of 10,000 gross tonnage 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.
Special requirements for every tanker, chemical tanker or gas carrier of 10,000 gross tonnage and upwards
- Shall comply with the following;
- 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 actuating system shall not put the other non-defective unit also out of operation.
- The main steering gear shall comprise either:
- Two independent and separate power actuating systems, each capable of operating conditions of main steering gear as we have seen above.
- At least two identical power actuating systems which can act simultaneously during normal operation capable of operating conditions of main steering gear as we have seen above.
If necessary, interconnection of hydraulic power actuating systems shall be provided, But 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 shall remain fully operational.
For non-hydraulic type
Do you have a steering system which is not hydraulic type??? Then SOLAS for you says “steering gears other than of the hydraulic type shall achieve equivalent standards”
- For tankers, chemical tankers or gas carriers of 10,000 Gross Tonnage and upwards, but of less than 100,000 tonnes Deadweight, all requirements as tanker ( mentioned above) is required but exempted from having ‘single failure criterion’ but they still have to demonstrate that, 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.
- If your ship which is a tanker, chemical tanker or gas carrier of 10,000 gross tonnage and upwards, but less than 70,000 tonnes deadweight there are different provisions which I am not including here. Please refer to the last portion of Regulation 29.
- ECR & Bridge should have motors running indication.
- 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; however, one of the circuits may be supplied through the emergency switchboard.
- Short circuit protection and an overload alarm shall be provided for circuits and motors. Protection against excess current, including starting current, if provided, shall be for not less than twice the full load current of the motor or circuit so protected, and shall be arranged to permit the passage of the appropriate starting currents.
- Where a three-phase supply is used an alarm shall be provided that will indicate failure of any one of the supply phases.
- The alarms shall be both audible and visual and shall be situated in a conspicuous position in the main machinery space or control room from which the main machinery is normally controlled.
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