5th Episode –
Marine Engineer’s Job and Life On Board
By Tat YEUNG
It is Tat Yeung again, a seagoing marine engineer.
What does a seagoing marine engineer do? What is a seagoing marine engineer life? Let us explore.
There are two main categories of ships, namely domestic and ocean going. I would like to focus on ocean going ship.
The ship’s engine department is responsible for daily operation, maintenance, repair and emergency preparedness of all the machineries on board. The machineries include propulsion, electricity generation, fire fighting equipment, pollution prevention/control equipment, habitability (ventilation, air conditioning, cooking, plumbing, refrigeration), cargo handling equipment … The list goes on.
How come the engine department has to handle so many things? Simple answer, the ship is alone in the ocean. It has to be self-supported for everything right from the propulsion of the ship to the daily life of the seafarers on board.
The engine department team typically consists of 8 to 10 persons only. About 3 to 4 are the senior officers holding higher qualification and responsibility. The rest are junior engine crew members. However, the team is working round the clock 24/7 to operate the various machineries.
Furthermore, the ship at sea is subject to motion, weather and rapid changing ambient conditions. These issues make the operation and the repair of machineries on board challenging as compared with land-based counterpart.
Commercial ships need reliable propulsion system to transport cargo across the oceans. Wind, tidal, solar energy are unreliable to power the propulsion system. Mechanical propulsion means using fuel is reliable and effective.
At present, it is not viable to use nuclear fuel for commercial ships mainly due to the very high safety standard. Nuclear fuel is used on naval ships and some scientific research ships.
The other choice of fuel is fossil fuel, i.e. oil or coal. It does not sound good in modern day concept of conserving the environment. However, take a look of the carbon footprint comparison below:
The propulsion system is made up of the prime mover and the propulsor.
The prime mover burns fuel to obtain heat. The heat is consequently converted into mechanical power, usually rotary, to drive the propulsor.
There are two main types of prime mover, namely external combustion and internal combustion.
Typical external combustion type consists of a steam boiler. The boiler burns fuel to raise steam. Steam is then directed to a steam turbine to develop mechanical power.
Typical internal combustion type burns fuel internally to develop the mechanical power. Car oil engine, except purely electric car, is an example. Gas turbine is also an internal combustion engine but is expensive to run. Therefore, it is not popular in commercial shipping except for special areas demanding very clean exhaust such as Alaska.
Most commercial ships employ internal combustion engine running on Diesel cycle (a thermodynamic process to convert heat energy from combusting fuel to mechanical energy), commonly known as diesel engine. Diesel engine uses low grade fuel and employs compression ignition mechanism compared with petrol fuel engine using the spark ignition mechanism, commonly found in cars. In this article, I am not going into details of the differences, in particular merits and demerits of the two.
Above is a view of the engine room at the top of the main propulsion diesel engine. It shows six of the eight cylinders of the engine.
This second photo is a view of the engine bottom part. Note the doors provide access into the engine for maintenance and repair work. Yes, we work inside the engine.
The propulsor takes up mechanical power from the prime mover to develop propulsion thrust. The thrust is then transferred through a thrust bearing to drive the ship through the water. Propulsor can be screw propeller, water jet or paddle. Screw propeller is the most common propulsor used in ocean going commercial ships due to reliability and efficiency.
The current trend is to employ multiple diesel engine driven generators to generate electrical power to feed a propulsion electrical motor. The motor then drives the propulsor. Such design provides high flexibility, controllability and reliability of the overall power supply, in particular on passenger ships where demand of electricity is high.
Besides propulsion, supplying electricity is the second main purpose of power generation on board. Machineries associated with the propulsion engine require electricity to operate. The primary electrical system is usually 3-phase 440V AC type. Where ships employing electrical propulsion, the electrical system may be rated to11KV.
Otherwise, electricity is used in many other aspects such as accommodation needs, communication, steering …
Generator can be driven by stand-alone prime mover or geared to the main propulsion engine. International rule requires more than one generator where they can be run independently to ensure availability and redundancy.
Fuel oil treatment
Ship uses low grade fuel oil in order to reduce cost. The fuel oil is a fuel product near the end of the oil refinery process (there are other products towards the process end such as bitumen but cannot be used as fuel). It is also known as heavy oil or residue oil. It is contaminated with refinery residues/wastes, sand/mud and water. It is also very viscous.
Centrifuge is usually used to remove the contaminants. The treated fuel has to be heated before being introduced into the diesel engines (main propulsion and auxiliary) or the steam boiler to burn.
Ships also carry marine grade diesel fuel oil which does not require much treatment, such as heating. The diesel fuel oil is not the daily fuel but as contingency reserve.
We cannot claim pollution free, rather pollution is reduced and controlled to internationally allowable level .
For instance, sewage is treated, oil content in bilge water is reduced and amount of pollutants in engine exhaust gas are controlled before they are discharged to the ambient environment.
To support living conditions on board, the engine department generates fresh water, operates refrigeration for food storage, provides service to the galley facilities, lighting, plumbing, laundry, ventilation, air-conditioning …
Watchkeeping is a traditional term that the engineer keeps an eye on the machineries.
The machinery operations in the engine room are to be monitored continuously to ensure reliability. Although automation is widely used, human attendance is still essential.
Usually, there are three teams each of two persons taking 4 hours on and 8 hours off roster. In case of highly automated system, taking turns, one person is on duty for 24 hours. Of the 24 hours, the duty person can take rest/sleep in his cabin in the night but respond to alarm that goes off when there is problem detected by the automated system.
Maintenance and repair of cargo handling gear such as lifting crane, wire, winch and powerpack to drive the gear.
Tanker carrying dangerous liquid cargo may be required to suppress the risk of explosion resulting from ignition of volatile combustible vapour. The marine engineer generates inert gas for this purpose.
Maintenance and repair
Machineries are subject to wear and tear. Thus, maintenance and repair is an important part of the marine engineer job portfolio.
When there is breakdown at sea, the repair may need to be carried out in very harsh conditions such as limited resources, the ship is alone at sea with limited manpower, and unfriendly environment such as sea motion.
The marine engineer has to carry out repair or even fabricate machinery parts.
The skills include bench fitting, welding, brazing, drilling and machining. The quality of the work required is to keep the machinery running to go home, where genuine spare part or professional repairer is available.
Fire, engine room flooding, blackout, crankcase explosion, scavenge fire are some of the various emergency situations a marine engineer may face and has to prepare to act. In particular, the initial action of the duty marine engineer is critical to the eventual control and elimination of the hazard.
If the situation has become uncontrollable, the last resort is abandon ship i.e. cramp into a small lifeboat, drift at sea and wait for rescue.
The marine engineer is responsible for the emergency readiness of emergency equipment/machinery such as emergency fire pump, fire damper, emergency generator, lifeboat engine …
Occupational Health and Safety
At sea, where the machineries are in full operation, the engine room is hot, humid and noisy.
Once I had to repair a steam valve with live steam emerging at about 4 kg/cm2. The steam was invisible but the heat was immense. It was the worst case of my sweating. I had to come out about every two minutes’ work to cool down before continuing. Well, this is unbelievable in modern occupational health and safety regime. However, the ship is alone in the vast ocean. Do it or die!
Many seafarers took salt tablet to replenish body salt loss due to sweating. Personally, I did not like using salt tablet. I let my body absorb naturally salt from food and drink to balance the loss. Thus, in the first week of joining a ship, I would feel tired. Afterwards, my body could have conditioned to the situation and reached a balance.
Chemicals are used in various areas such as boiler water treatment, diesel engine cooling water treatment and cleaning. Marine grade diesel oil is a good solvent of grease and hard oil sludge deposit. I first used diesel oil to clean my hands of dirt followed by soap to wash away the diesel oil.
The first time I used diesel oil to clean some machinery part was amazed by the effect. However, my hands then developed blisters covering all over my hands in reaction to the diesel oil. After a few days, the blisters retreated. Since then my hands are conditioned to handle diesel oil, heavy oil and some cleaning chemicals. However, this is in fact not a good sign.
Maintenance work of the main propulsion engine involved getting into the space inside the engine. Inside the engine, there was lubricating oil drip everywhere. The atmosphere was filled with oil mist. It was slippery with many tripping obstacles. I would end up totally soaked with lubricating oil. Lubricating oil contained various chemicals such as anti-rust, anti-foaming, detergent etc.
While working on inert gas generator, unavoidably I inhaled inert gas which was the product of combustion full of hazardous substances.
While handling chemicals, the chemicals might have penetrated into my body through the skin or respiration. The effect may not surface until my body system has aged and become weak. I do not know when and how these chemicals will come to haunt me!
I view a marine engineer is Jack of all trades. As a marine engineer, I learned to work independently, to make decision promptly in response to emergency situation, to diagnose the whole scene, to control pollution…
What I value most is the hands on practical experience acquired.
On the other hand, the tough life, the small social circle on board, the exposure to occupational hazards have marked me (I have to bear the hazardous materials that might have entered into my body for the rest of my life like tattoo). I am not picky on food. I eat to survive not to please my taste buds. It could be another way to protect the environment.
I shall elaborate in more details of the technical side of shipboard machineries and the international regulations governing the maritime industry.