STARTING UP THE SHIP'S MAIN ENGINE TO MOVE: A complex process

"Starting up a ship's main engine might appear as simple like turning the knob to the desired speed setting then all of sudden the engine starts .But it is not true in case of ship engine."In reality, It takes some preparation before we could get to that easy part i.e., turning the knob to the desired speed.

There are four ancillary systems which are needed in order to start up & operate the ship's main engine??

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??Even when the ship is in port the fuel, lube oil & cooling water systems are kept running and in continuous circulation to ensure that the main engine can be started within a few minutes if needed, the engineers will receive a one hour notice prior to the ship's departure to give them time to make the engine ready??.

??The first thing to do is to start up an extra generator, this is to ensure that the system has enough electrical power to handle the added load.

??Next on the list is lubrication which is accomplished by turning the engine using the turning gear, this is necessary to ensure that the lubricating oil gets to cover the contact surfaces of all moving parts and also to pre-lubricate the cylinder liner and piston rings after a few revolutions the turning gear is stopped and disengaged.

??Next is the starting air system, these engines are commonly started by means of compressed air which is stored in large air bottles maintaining a pressure of around 28 to 30 bar as per SOLAS regulations the volume of air contained in these air bottles at full capacity should be sufficient to start the engine for 12 consecutive times without replenishment from the compressors, this compressed air is injected into the cylinders and pushes down the pistons to initiate reciprocating motion which is then converted into rotary motion by the crankshaft.

??After opening the main valve from the air bottle the next step is to open the starting air control valve to the distributor. The distributor controls the air injection sequence during starting.

??Once all the starting parameters are met.?The main engine will be ready to start??

?The bridge is then informed that the main engine is ready for trial starting.

?The main engine is put on standby condition.

??In this instance the auxiliary blowers will start and after which air blowing will be carried out. Air blowing is the injection of compressed air into the cylinders while keeping the indicator open in order to release any moisture or other residues inside the cylinders. Fuel is not injected at this time so there will be no combustion.

??After this the indicator cox are closed and the engineers can proceed with fuel running.

??Firstly, the engine will be tried on dead slow ahead & then dead slowest turn.

?Most chips are designed with engines directly coupled to the propeller shaft so reversing the rotation of the propeller means the engine itself needs to stop first and then reverse its rotation.??

When the engineers are satisfied?? that the engine controls are working and in good condition they turn over the controls to the bridge?.

??From here the bridge officers will be able to start and stop the engine as needed during maneuvering and gradually increase the speed to prepare the ship to go underway.??

??At around the midpoint between slow and half there is a barge speed? range which the engine needs to get through as fast as possible? ,the engine will have heavy vibrations due to the equal frequency of engine impulses and torsional vibration at this critical speed range.

??At full ahead the engine will be running at around 50 percent load in this condition the pressure from the exhaust gas becomes ??powerful enough to run the turbocharger at a sufficient speed so that the auxiliary blowers will no longer be needed to provide additional airflow to support combustion??.??

??Now the ship will be able to build up momentum? and be ready to increase speed? once it hits open ??water at navigation full, the engine speed can be slowly increased to its normal continuous rating which is usually at around 75 percent of the maximum continuous rating.

??At this point a whistling?? sound can be heard from the turbocharger which can run at speeds of around 13000 rpm.

?Once the desired speed is achieved and the ship has reached open sea ,commence of sea passage is declared and maneuvering operations are completed.???