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Critical equipments are equipments whose failure will lead to a potential hazardous situation or an accident, thereby causing injury to personnel or loss of life or damage to marine environment or property. This causes deviation or failure of the ISM objective 1.2.2 of ISM code.
PROVISION IN ISM:- Element 10.3 of ISM code states----
     The company should establish procedures in its safety management system to identify equipment and technical system, the sudden operational failure of which may result in hazardous situation. The SMS should provide for specific measures aimed at promoting the reliability of such equipment or systems. These measures should include the regular testing of standby arrangement or equipment or technical systems that are not in continuous use.
     Hence SMS must have with respect to the critical equipment have procedures:-
1) To identify them
2) To ensure their test and functional reliability
3) To establish and use the alternative arrangements on sudden failures.
4) To test standby equipments
5) To ensure that a single failure does not lead to a critical situation
6) To ensure that a system or equipment which is standby or unoperated or inactive for a certain time is tested regularly and prior to conducting the critical operation.
7) There is always minimum level of spares for critical equipments.
                           The list of critical equipments or systems can vary according to ship type and operation .once identified appropriate tests and other procedures should be developed to ensure reliability.
As per element 7 of Ism code, the company must establish procedures for preparing plans, instructions, checklists for key shipboard operations related to the safety of the ship, and prevention of pollution and safety of personnel.
            Normally criteria for choosing a critical equipment or operation lie as its potential to carry on to a hazardous situation. Thus a critical equipment or operation is that whose direct failure will lead to an accident. Hence with combination with element 10 the following shipboard equipments/ items are subjected to inspections and tests (but are not limited to)
1) Hull and superstructure steel work
2) Safety, firefighting and LSA equipment
3) Navigational equipment
4) Steering gear
5) Anchoring or mooring gear
6) Main engine and auxiliary engine
7) Cargo handling equipment
8) I.G. system
9) Electrical installation
10) Fire detection and alarm system
Similarly shipboard operations can be categorized into :-
1) Normal operation:- Error becomes apparent, only after occurrence of a hazardous situation.
2) Critical operation: - Error directly leads to accidents. Critical operations will include ( but are not limited to) :-
a) Navigation in restricted visibility
b) Navigation in high density traffic area
c) Navigation in restricted/ narrow area
d) Heavy weather operation
e) Handling of hazardous cargo and noxious substances
f) Bunkering and oil transfer operation at sea
g) Cargo operation on oil/ gas/ chemical tankers
h) Critical machinery operation like OWS, INCINERATOR, EMERGENCY FIRE PUMP etc.


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1) It is defined as the ability of a ship to regain its upright equilibrium position, after the removal of external factor which caused the vessel to heel at an angle.
2)It gives the stability information of a vessel under the condition that the outside water is static.
3)It is expressed in terms of metacentric height. i.e. GM ( for angle of heel up to 10 degree) and righting lever GZ ( for angle of heel above 10 degree)
4)It’s unit is meter
5)Static stability at two different angle of heel can be the same.
1)It is defined as the energy required heeling the ship from upright equilibrium till the angle of heel in question.
2)It gives the stability information of a vessel considering dynamic behavior of the sea.
3)It is expressed in terms of the area under righting moment curve. ( or GZ curve multiplied by displacement of the ship in tons)
4)It’s unit is ton-meter-radian
5)The dynamic stability at two different angle of heel cannot be the same

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