The Engineering Diary

​ Black Smoke from the Funnel: What to do? Black Smoke from the funnel is a sign of poor maintenance and malfunction of the machinery. It is a serious issue as it violates Marpol 73/78 Annex VI and can lead to inspections and detention of the ship. In a ship with multiple machines the identification of the faulty unit is a difficult task. The reasons black smoke is wrong are:                                    1.       It indicates that shipkeeping and maintenance is not proper and up to the mark. 2.       It indicates the lack of competency of the engineers. 3.       It is polluting. 4.       It increases the risk of an uptake fire. Marpol Annex VI has set standards for air pollution and the sulphur content of the e...

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Fuel Oil Testing On-board On-board testing of the fuel could be carried out during the bunker operation by one of the engineering staff not required to supervise or monitor the bunkering operation. The following tests could be carried out:   Water content   Viscosity   Density   Compatibility   Check for abrasive fines Although the tests are not as accurate as a shore based laboratory the tests would indicate whether the fuel loaded is the same as the fuel quality ordered and therefore the bunker receipt. Importance of Fuel Oil Sampling A representative sample would be obtained by a permanent sampling probe fitted close to the bunkering manifold. The rate of sampling would ensure that a sampling quantity required is taken over the full duration of the bunkering operation. The sample container is then thoroughly mixed before being poured into new, clean containers. The containers are then sealed and signed before being sent to the shore testing facility. Effects ...

In today’s world, the four main materials used for building boats, when we talk at the level of mass manufacturers, are steel, aluminium, fibre-reinforced plastic (FRP), and polyethylene. Let us speak about each of these in greater detail. Steel Steel is one of the most popular materials used for boats and has consistently been the material of choice for the past century. Its high strength, durability, resistance to abrasion, and relatively low cost are some of the main reasons why steel is widely used in the industry. However, in the wake of the development of new composite materials, better and cheaper alternatives are being used for manufacturing boats of equal size and strength but considerably lesser weight. This has reduced the importance of steel in boat building to an extent, although it is still used extensively for larger ships. From the point of view of sustainability, steel has a practically airtight production process that produces minimal constructional waste. In addition...

  Welding Methods And Weld Defects PART 20   Welding is one of the most widely used hot-work processes used in the shipbuilding industry. The development in welding technology has enabled the industry to produce perfectly watertight and oil-tight joints. Welded joints as compared to riveted joints are much easier to produce and they reduce the cycle time of the project. Welded joints have also resulted in reduced steel weight and require less to negligible maintenance compared to rivet joints. The major contribution of welding technology to the shipbuilding industry is the possibility of producing smooth hull surfaces, therefore reducing the bare hull resistance and power requirements considerably.   Welded joints as compared to riveted joints are much easier to produce and they reduce the cycle time of the project. Welded joints have also resulted in reduced steel weight and require less to negligible maintenance compared to rivet joints. The major contribution o...

Types of Ships Cargo ships are classified into various types on the basis of purpose, size, type of cargo etc. The economic factor is of prime importance in designing a merchant ship. Every owner wants maximum return on their investment which means a ships construction not only depends on the current economic necessities but the factor of future adaptability also plays a part. From the preliminary design of a vessel due for construction, the following information can be obtained: 1.      Dimensions 2.      Displacement 3.      Stability 4.      Propulsive characteristics and hull form 5.      Preliminary general arrangement 6.      Principal structural details A layout of the various ship types and their subdivisions will be listed out, covering a wide range of all vessels in operation.  The type of ship plays an important role in deciding the above mentioned parameters. Types of Ships Ships a...

Gearing and tail shafts Vessels with low speed engines typically use direct drive from the crankshaft to the tail shaft with its propeller. Smaller domestic commercial vessels typically operate with high speed engines where direct drive shafts would revolve too fast to drag water across their propellers without efficiency losses due to cavitation (bubbling in the water flow). Consequently a gearbox is used to provide reduced speed of the shaft, reverse propulsion and through a clutch mechanism, disengaged propulsion. Gears and clutch mechanisms Principles of marine gear boxes Gearing is used in drive trains (sets of intermeshed gear wheels) to alter direction, position or speed/mechanical advantage of propulsion and auxiliary equipment such as winches, pumps and steering. The gear and shaft driven directly by the motor can be called the input and the final gear and shaft it drives can be called the output. Drive train A shown below illustrates reduction and reversal of the output, driv...

Maintenance Running checks should include: Gear box - oil level; inspect for leaks around casing; ensure pins and bolts in mechanical linkages are secure. Shaft bearings - check oil level in bearing sump; leakage through end seals; temperature of bearing. Stern gland - a leaking stern gland is a normal routine and is adjusted as a matter of course. See stern tubes in section above. Propeller shaft - check noise level to determine whether it is increasing. Regular maintenance schedules will include: Gearboxes - Adjust clutches and operating mechanism, clean filters and clean oil coolers. Drive train  Engine and shaft bearing moutings, loose shaft coupling bolts (perhaps due to mis-alignment) may need to be tightened. Mis-alignment of intermediate bearings will show up by overheating of the bearing. Survey servicing and repair schedules will include: Weardown survey- Allowance is determined by the manufacturer, but rules of thumb range from 3% of diameter as due for replacement to 6%...

Diesel fuel systems Direct supply The fuel tank with filler cap and venting breather is measurable by a sight gauge. Fuel is directed to the mechanical fuel pump through the supply line, along which primary and secondary filters ensure clean fuel only reaches the mechanical pump. Additional water separators are often fitted at the primary filter position. A manual lift pump is provided to assist bleeding (priming) the fuel line of trapped air after servicing the fuel filters. The cam driven mechanical pump forces the fuel to the injectors when it is required for combustion. Other fuel line components include: Baffle - They are fitted to prevent free surface effect. This affects the stability of the vessel and in extreme cases can cause vessels to capsize. Drain valve - is fitted to the lowest part of the tank. Its purpose is to drain water or sediment from the tank. A plug or cap is fitted so, if the valve vibrates open, the fuel is not lost or causes a fire risk. Water can be in the t...

Quick closing valves: What are Quick Closing Valves? On ships, marine diesel engines draw fuel from reservoirs or storage tanks which are also known as service tanks. All these tanks are provided with a specific valve known as quick closing valve, in order to shut the fuel supply in case of emergency such as fire. The closing of the valve can be done either manually, hydraulically or even by using compressed air. A typical arrangement consists of wire operated valves with wire pull livers located externally to the machinery space. If you want to know more about other types of valves, read these articles about gate valves, globe valves and butterfly valves. Construction and Working Quick closing valve is a kind of pressure reducing valve in which the an automatic process control valve for fluid pressure control is used for unmanned machinery spaces. This can be done by careful selection of valve trim, i.e. the parts of the valve that come in contact with the controlled fluid and form an...

What is a Ship's Stern Tube? Everyone knows that a ship is propelled with the help of a propeller located at the aft of the ship. However, they may not know how the propeller is connected to the engine located inside the ship. A stern tube, situated at the aft of the ship, helps in this purpose. The propeller is the only part of ships machinery, apart from the rudder, that is located outside the ships engine room. Have you ever seen the propeller of a ship and wondered how it is connected to the inside of the ship? Have you ever wondered where the shaft holding the propeller goes when it vanishes into the ships hull? If so, then you have come to the right place. The propeller, a part of the propulsion system of the ship, needs a power source to rotate it. A marine diesel engine located inside the ship supplies the power to the propeller. Both the diesel engine and propeller are very heavy: locating them both at the same place inside the ship would disturb the ships stability. It is...

Principles of internal combustion engines Operating principles Combustion is the process in which fuel heated beyond its flash point ignites and gives off energy and the waste products as exhaust gasses (carbon dioxide, carbon monoxide and water). The three elements necessary for combustion (or fire) are: Oxygen + Heat + Fuel = Explosion or Fire Internal combustion engines suck in air to access the oxygen and use hydrocarbon fuels including petrol, diesel and liquid propane gas. The internal combustion process Internal combustion engines use successive explosions of atomised air and fuel mix to force a piston down a gas tight internal cylinder. The piston is connected through a big end bearing to a cranked shaft that is weighted by a flywheel to assist its rotary momentum. Thus with three primary moving parts (piston, connecting rod and crankshaft) the pistons reciprocating motion drives the crankshafts rotary motion. A sturdy metal casting of an engine block holds the internal parts a...

How Does a Diesel Engine Work? When people think of a diesel engine, they often think of a big truck which hauls a lot of items. Although diesel engines are commonly found in bigger vehicles, they can really be in any size vehicle. The benefit of a diesel engine is getting better miles per gallon. Since truck drivers are constantly on the road for most of the day, it is more economical for them to drive a diesel-powered vehicle versus a petrol-powered vehicle. The reason that diesel engines provide better gas mileage is because they have fewer revolutions per minute. Unlike with a petrol engine, the air is the only thing that gets compressed in the chamber. This highly compressed air is then used to ignite the diesel fuel. This differs from the petrol engine which requires separate spark plugs to generate a spark for ignition. The diesel engine does not require such a spark. It relies solely on the highly compressed air to generate enough heat for a proper ignition of its fuel. The Fou...

Nonrenewable Resources What Are Nonrenewable Resources? A nonrenewable resource is a natural substance that is not replenished with the speed at which it is consumed. It is a finite resource. Fossil fuels such as oil, natural gas, and coal are examples of nonrenewable resources. Humans constantly draw on the reserves of these substances while the formation of new supplies takes eons. Renewable resources are the opposite: Their supply replenishes naturally or can be sustained. The sunlight used in solar power and the wind used to power wind turbines replenish themselves. Timber reserves can be sustained through replanting. Understanding Nonrenewable Resources Nonrenewable resources come from the Earth. Humans extract them in gas, liquid, or solid form and then convert them for their use, mainly related to energy. The reserves of these substances took billions of years to form, and it will take billions of years to replace the supplies used. In economic terms, nonrenewables are resources...

Types of Renewable Energy Sources Solar Energy Humans have been harnessing solar energy for thousands of yearsto grow crops, stay warm, and dry foods. According to the National Renewable Energy Laboratory, more energy from the sun falls on the earth in one hour than is used by everyone in the world in one year. Today, we use the suns rays in many waysto heat homes and businesses, to warm water, or power devices. Solar, or photovoltaic (PV), cells are made from silicon or other materials that transform sunlight directly into electricity. Distributed solar systems generate electricity locally for homes and businesses, either through rooftop panels or community projects that power entire neighborhoods. Solar farms can generate power for thousands of homes, using mirrors to concentrate sunlight across acres of solar cells. Floating solar farmsor floatovoltaicscan be an effective use of wastewater facilities and bodies of water that arent ecologically sensitive.   Solar supplies a ...

Problems with low pH pH that is too high or too low will have negative effects on the fish. Low pH can cause damage to the gills, skin and eyes. Higher H+ concentrations will also increase the permeability of the gills, leading to leakage of Na+ and Cl which creates osmotic problems. First, the effects can be regis-tered as a reduction in growth; too low a pH will kill the fish. In natural populations, the pH may vary from 5 to 9, but for aquaculture facilities it is rec-ommended to be in the range 6.59. Problems with metals in the water are best avoided; tolerance may vary with fish species and life stage, with newly hatched fry being especially sensitive. For crayfish, for example, the pH and alkalinity must be high because they utilize Ca2+ in the water for shell synthesis. The solubility of metal ions in the water will increase with reduction in pH. There have been particular problems with the concentrations of aluminium (Al+ + +) in fish farming; this metal leaches from the soil o...

Power Generation On Ships: A ship is equivalent to a floating city that enjoys almost all privileges available to any operational set-up on land. Just like any conventional city, the ship also requires the basic amenities to sustain life on board, the chief among them being power or electricity. Electricity on ships is generated by an alternator or generator. Shipboard power is generated when a prime mover and alternator works together. For this purpose, an alternating current generator is used on board. The generator works on the principle that as a magnetic field rotating around a conductor varies, a current is induced in the conductor. The generator consists of a stationary set of conductors, wound in coils of iron core also known as the stator. A rotating magnet known as rotor turns inside this stator, producing a magnetic field, which cuts across the conductor and generates an induced EMF or electro-magnetic force as the mechanical input causes the rotor to turn. The magnetic fiel...

Operation of the turbo charger on a diesel engine In a four stroke engine, exhaust gases flow from each cylinder into the exhaust manifold and then past the turbine blades of the turbo charger. With the engine running at full speed, the turbo charger can obtain speeds up to 100,000 revolutions per minute (rpm). The air compressor blades will revolve at the same speed. Air is drawn through the air cleaner and forced under pressure into the intake manifold. When the inlet valve opens on the induction stroke, with the piston descending in its cylinder, air is forced into the cylinder. It is necessary to reduce the turbo charger speed in stages or slowly for two reasons: If the engine speed is reduced from full engine speed to stop quickly and the bearings of the turbo charger are lubricated by the main engine driven lubricating oil pump, the engine, on stopping, will cease to supply the lubricating oil to the turbo charger bearings. Because of its high speed, it will take some time for th...

Renewable energy, often referred to as clean energy, comes from natural sources or processes that are constantly replenished. For example, sunlight or wind keep shining and blowing, even if their availability depends on time and weather. While renewable energy is often thought of as a new technology, harnessing natures power has long been used for heating, transportation, lighting, and more. Wind has powered boats to sail the seas and windmills to grind grain. The sun has provided warmth during the day and helped kindle fires to last into the evening. But over the past 500 years or so, humans increasingly turned to cheaper, dirtier energy sources such as coal and fracked gas.  Now that we have increasingly innovative and less-expensive ways to capture and retain wind and solar energy, renewables are becoming a more important power source, accounting for more than one-eighth of U.S. generation. The expansion in renewables is also happening at scales large and small, from rooftop sol...