Text 11. Functions of auxiliary machinery

Besides running and maintaining the main propulsion machinery of the ship, the engine officer has a great deal of auxiliary machinery to look after. Auxiliary machinery covers everything mechanical on board ship except the main engines and boilers. It includes almost all the pipes and fittings and the equipment needed to carry out a number of functions. These functions may be summarized as follows: to supply the needs of the main engines and boilers. Air compressors are used to supply compressed air for starting engines. Coolers are used for cooling either oil or water. Water for the boilers is also heated before being admitted into the boiler by feed water pumps. This increases the efficiency of the boiler.

- To keep the ship dry and trimmed. This is done through the bilge an ballast pumping systems. Bilge pumping system removes water which has gathered in machinery, cargo and other spaces. Ballast pumping system pumps water into and out of ballast tanks. In general cargo ships, these systems are usually interconnected and served by the same pumps. In tankers an other bulk carries, these systems are completely separate, because these ships may need to ballast at 12,000 tons/hour and therefore need larger pumps.

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- To supply domestic needs such as fresh and sea water, sanitation; heating or cooling of air, ventilation.

- To apply the main power of the engines for propulsion and manoeuvring. The engine power is transmitted to the propeller by a line of shafting. This is made up of the thrust shaft, intermediate shafts and the propeller shaft. Steering gear is also necessary to operate the rudder for manoeuvring.

- To supply the ship with electrical power and lighting. This is done by steam of diesel-powered generators. To moor the ship and handle cargo. Deck machinery is extensive and varied. It can be divided into anchor-handling machinery (windlasses and capstans ), mooring machinery (winches and capstans), and cargo-handling machinery ( winches and cranes ). It also includes cargo oil pumps.

- To provide for safety. Firefighting and fire detection equipment, lifeboat engines and launching gear are also included.

- To prevent oil and sewage pollution.

Text 12. Maintenance schedule of marine diesel engine

Engine builders supply detailed instructions on the operation and maintenance of their machinery so that regular maintenance work can be carried out and breakdowns can be kept to a minimum. These instruction manuals are usually kept by the Chief Engineer, but are made available to all members of the engine-room staff. The intervals at which an engine and its parts must be inspected will vary from make to make( зависят от модели двигателя ) and will depend on the use the engine has been put to.

At frequent intervals, fuel pumps should be examined and adjusted, if necessary. When the engine is running, this will be shown by comparing engine indicator cards and by exhaust temperatures. Pistons should also be examined frequently for cracks.

At intervals of six weeks, the fuel valves should be taken out and carefully inspected. Atomizers and filters can be washed with clean diesel fuel oil. Cleaning rags must not be used because they leave behind small pieces of fluff, which may block the holes. Valve seats should be tested and if they are pitted or scratched, the surface should be reground.

At intervals of six months piston heads if cooled, must be inspected for deposits of carbon in cooling spaces and cooling pipes. When new piston rings are fitted, care must be taken to ensure there is sufficient clearance to allow for the expansion of the rings. Exhaust valves and manifold must also be examined and excessive carbon deposits removed. All carbon deposits should be removed from

cylinder ports. Cylinder liners must be examined externally for deposits of scale. If these deposits cannot be removed by flushing with water, then the liner must be removed for cleaning. The liner should also be measured for wear and renewed, if the limit for wear has been reached. The clearance of connecting-rod top and bottom ends should also be examined and adjusted if necessary.

At intervals of one year the manoeuvring gear must be examined for wear at the joints of levers and rods. The alignment of the crankshaft should be checked and any incorrect alignment corrected.

The main bearings must be examined and readings taken for wear. The clearances of all crankshaft bearings must be maintained at the figure recommended by the makers. Finally, starting air piping and air bottles must be cleaned, and the lubricating oil system thoroughly examined and cleared of deposits.

It must be emphasized that the above-mentioned parts are only some of the items which must be regularly maintained to ensure the efficient working of the machinery.

Text 13. Repairs

CYLINDERS. - Cylinder liners are a source of work for repair yard. Liner casualties occur either from wear or cracks. Wear is a normal result of engine use.

Liners that are originally fitted so that they will drop into place in the jackets with little or no pressure, sometimes require from 200 to 300 tons hydraulic pressure to remove them. This is caused by the carbon or scale accumulation that gets into the seating. After this seating deposit is once broken, no great pressure is required to move the liner the rest of the way.

Cracked liners are encountered occasionally, but in practically every case cracking is due to no fault in the liner itself. It usually results from piston seizure, and such seizure usually result from inadequate cooling of the piston. No attempt is ever made to repair cracked liners, renewal being the only remedy.

CYLINDER COVERS ( HEADS ) - The cover is usually the most complicated casting on the engine, and as such suffers most from heat trouble. To make a successful cover repair, electric welding must be done skillfully.

Once an emergency repair to a cracked cover was made on shipboard by the crew. Both bridges, between injection valve and inlet and exhaust valves cracked on bottom face of cover. The injection valve hole was bored out and threaded and a cast iron bush screwed in. a hole large enough to remove the cracks was then drilled on each side of the injection valve opening and threaded, after which a copper plug was screwed tightly into each one. Although this type of repair is not to be recommended, it did work well in this case.

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Text 14. MARPOL 73/78

The International Convention for the Prevention of Pollution from Ships, 1973 as modified by its Protocol of 1978, is the most important anti-pollution treaty ever adopted by IMO.

The convention is usually known as MARPOL 73/78.

Although pollution resulting from tanker accidents caused some concern, the convention was primarily aimed at pollution resulting from routine tanker operations, which was the greater cause of pollution from ships.

When a tanker has discharged its cargo it has to fill some of its cargo tanks with ballast water in order to provide the necessary stability.

Mixtures of oil and water also result from tank cleaning, which is generally done by spraying the tank walls and bottom with water.

Pollution can also come from engine room bilges of all ships (not only tankers), since bilge water is always contaminated by oil. In 1954 the normal practice was to pump these mixtures of oil and water into the sea.

The convention deals not only with oil but with all forms of marine pollution.

Most of the technical measures are included in five annexes to the convention which deal respectively with the following:

Annex I - Oil

Annex II -Noxious (вредный, ядовитый) liquid substances carried in bulk (e.g. chemicals)

Annex III - Harmful (вредный, опасный ) substances carried in packages (e.g. tanks and containers)

Annex IV - Sewage

Annex V - Garbage

MARPOL 73/78 requires:

1. An initial survey before the ship is put into service or before an International Oil Pollution Prevention Certificate is issued.

2. Periodical surveys at intervals not exceeding five years.

3. A minimum of one intermediate survey during the period of validity of the IOPP Certificate.

4. Unscheduled inspection or mandatory (обязательный ) annual surveys must be carried out.

The International Convention for the Prevention of Pollution from Ships, 1973, as modified by its Protocol of 1978 (MARPOL 73/78) entered into force on 2 October, 1983.

It is generally regarded as the most important international treaty ever adopted in the struggle against pollution of the sea.