M61

M61(Dec2003)(cont)(Rev.1
Feb 2022)(Rev.2July 2023)(Rev.3Feb 2024)

Starting Arrangements of Internal Combustion
EnginesM61.1 Mechanical starting arrangements
M61.1.1 The arrangement for air starting is to be such that the necessary air for the firstcharge can be produced on board without external aid.
M61.1.2 Where the main engine is arranged for starting by compressed air, two or more aircompressors are to be fitted. At least one of the compressors is to be driven independent ofthe main propulsion unit. The capacity of one of the said independently driven compressors
or the combined capacity of independently driven compressors shall not be less than 50 % of
the total required.
M61.1.3 The total capacity of air compressors is to be sufficient to supply within one hour thequantity of air needed to satisfy M61.1.5 by charging the receivers from atmosphericpressure. The capacity is to be approximately equally divided between the number ofcompressors fitted, excluding an emergency compressor which may be installed to satisfy
M61.1.1.
M61.1.4 Where the main engine is arranged for starting by compressed air, at least twostarting air receivers of about equal capacity are to be fitted which may be used
independently.
M61.1.5 The total capacity of air receivers is to be sufficient to provide, without their being
replenished, not less than 12 consecutive starts alternating between Ahead and Astern ofeach main engine of the reversible type, and not less than six starts of each main nonreversible type engine connected to a controllable pitch propeller or other device enabling thestart without opposite torque. When other consumers such as auxiliary engines starting
systems, low-pressure compressed air systems (see UR M84.2.2), control systems, whistle,etc., are to be connected to starting air receivers, their air consumption is also to be taken
into account.
Regardless of the above, for multi-engine installations the number of starts required for eachengine may be reduced upon the agreement with the Classification Society depending upon
the arrangement of the engines and the transmission of their output to the propellers.

Note:
1. Rev.1 of this Unified Requirement is to be uniformly implemented by IACS Societies on
ships contracted for construction on or after 1 January 2023.
2. Rev.2 of this Unified Requirement is to be uniformly implemented by IACS Societies on
ships contracted for construction on or after 1 January 2025.
3. Rev.3 of this Unified Requirement is to be uniformly implemented by IACS Societies on
ships contracted for construction on or after 1 July 2025.
43. The “contracted for construction” date means the date on which the contract to build
the vessel is signed between the prospective owner and the shipbuilder. For further
details regarding the date of “contract for construction”, refer to IACS Procedural
Requirement (PR) No.29.
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M61

M61(cont)

M61.2 Electrical starting
M61.2.1 Where the main engine is arranged for electric starting, two separate batteries are tobe fitted. The arrangement is to be such that the batteries cannot be connected in parallel.
Each battery is to be capable of starting the main engine when in cold and ready to startconditions. The combined capacity of the batteries is to be sufficient without recharging toprovide within 30 minutes the number of starts of main engines are required above in case of
air starting.
M61.2.2 Electric starting arrangements for auxiliary engines are to have two separate
batteries or may be supplied by separate circuits from the main engine batteries when suchare provided. In the case of a single auxiliary engine only one battery may be required. The
capacity of the batteries for starting the auxiliary engines is to be sufficient for at least three
starts for each engine.
M61.2.3 The starting batteries are to be used for starting and the engine’s own monitoring
purposes only. Provisions are to be made to maintain continuously the stored energy at alltimes.

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IACS Req. 2003/Rev.3 2024