4 SHIPS IN OPERATION
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1515 - Revised Design Guidelines and Operational Recommendations for Ventilation Systems in Ro-Ro Cargo Spaces - Part 2 - Operational Recommendations for Minimizing Air Pollution in Ro-Ro Cargo Spaces - 4 SHIPS IN OPERATION

4 SHIPS IN OPERATION

4.1 Loading and unloading

Even if the cargo handling on a ship is well planned and the ventilation system is well suited to the planned traffic density, this may still not be enough to ensure that acceptable air quality is maintained under all vehicle handling conditions.

It is extremely important that the ventilation system is operated in the most effective manner under the prevailing operational and weather conditions.

The personnel responsible for loading and unloading of vehicles should consult with the officer responsible for vehicle deck ventilation to familiarize himself with the ventilation system on board (the supply and exhaust air openings and the design air flow) and decide whether the ventilation is adequate in the light of the traffic density, vehicle type and other considerations on a given occasion.

It is important that the supply air has free passage to the ro-ro cargo spaces and ventilation openings should not be unnecessarily obstructed.

If auxiliary air-jet systems have been installed, vehicles should be stowed in such a way that the air jets are allowed to operate at maximum effectiveness for as long as possible.

4.2 Limitation of exhaust emission production

The most effective way of reducing exhaust emissions is to ensure that vehicles spend as little time as possible on board with their engines running. This applies not only to cargo-handling vehicle (trucks, tractors, etc.) but also to vehicles being carried as cargo (cars, coaches, long-distance trucks, etc.). The speed at which the vehicles are driven on board should also be appropriate to the prevailing conditions.

Exhaust emissions are greatly influenced by driving techniques and the temperature at which an engine is running. Smooth and steady driving of a vehicle with a warm engine will generate the lowest exhaust gas emissions. Sudden and heavy acceleration will cause a substantial and often unnecessary rise in the pollution level. This is particularly true when an engine is cold. Since slow speeds and slow acceleration produce significantly lower levels of air pollutants than high speeds and quick accelerations, vehicles should be accelerated very slowly and kept at low speeds.

The essential points to note include the following:

  • - condition of the engines;

  • - driving techniques;

  • - organization of the work (as few engines as possible running at the same time);

  • - ensuring that drivers do not start their engines sooner than necessary; and

  • - ensuring that the traffic flows steadily (thereby eliminating heavy acceleration and high speeds). Exhaust emission control equipment for both diesel and petrol engines may influence air quality during embarkation. However, this is likely to have little effect during disembarkation due to cold starting of engines.

4.3 Limitation of exposure

The car decks on ferries are usually equipped with exhaust air ventilation. The supply air is generally admitted through the ramp and the air is removed by exhaust air fans at the other end of the car deck.

A person carrying out heavy manual work uses up twice as much air as a person doing light work. As a result, he will inhale a correspondingly higher proportion of pollutants. Consequently, the work should be organized so that heavy physical work is avoided in areas where the pollution level is high. Nobody should be unnecessarily exposed to hazardous concentrations of exhaust gases.

4.4 Recommendations for specific ship types

4.4.1 Car ferries

During disembarkation at peak times, the highest average concentration of pollution (exhaust gases) in the vehicle deck will occur furthest away from the ramp, in the proximity of the exhaust air fans. Work on the car deck should therefore be organized to eliminate the need for personnel occupying the area of the car deck in which the pollution concentration is highest.

The embarkation and disembarkation should be organized so that no direct queues form inside the ship or in the ramp opening. The embarkation rate should be suited to the capacity of the fans and the flow of outdoor air supplied.

Embarkation should be organized so that ventilation openings, or air jets in an auxiliary system, are not unnecessarily obstructed.

Drivers should be given printed instructions for embarkation/disembarkation. A suitable leaflet could be given to drivers when the tickets are issued or notices posted for examples: Exhaust fumes constitute a health hazard. Do not start your engine before the signal is given and obey instructions.

On enclosed vehicle decks, instructions to start engines should not be given until doors leading to the ramps are open.

4.4.2 Ro-ro ships carrying heavy vehicles

Most of the cargo on ro-ro ships is handled by vehicles. Large trucks and tractors are used for cargo loading and unloading. Trucks of various sizes are used to stow the cargo in the ro-ro cargo spaces. On enclosed vehicle decks, instructions to start engines should not be given until doors leading to the ramps are open.

It is important to eliminate unnecessary exhaust emissions during cargo handling. The vehicles should be kept moving and queues should not be allowed to form. Avoid having vehicles standing with their engines idling. This applies particularly to any waiting during loading and unloading on board and to vehicles on lifts. At these times the ro-ro cargo spaces should be well ventilated.

It is also important to ensure that supply air and exhaust air openings are kept clear and are not obstructed unnecessarily. Failure to observe this can result in the ventilation system not performing effectively.

Attention should be drawn to the fact that exhaust gases can accumulate in poorly ventilated areas and in low-lying areas. A cold engine discharges twice as much pollution as a warm engine.

4.4.3 Car carriers

Owing to the general uniformity of cargo on car carriers, effective organization of embarkation/disembarkation should be possible, thereby avoiding the formation of queues and the resulting unnecessary exhaust emissions.

Drivers should be given printed instructions for driving techniques and should be informed of the importance of not running the engines more than necessary. A vehicle driven slowly and with slower acceleration will emit much less pollutant than a vehicle driven faster and with higher acceleration. Furthermore, a cold engine will often emit twice as much pollutant as a warm engine.

It is therefore recommended that engines be warmed up before the vehicles are driven on board. Vehicles with engines running should not be permitted in the vicinity of the "lashing gang".

Parent topic: Part 2 - Operational Recommendations for Minimizing Air Pollution in Ro-Ro Cargo Spaces
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