Marine engineering

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Marine engineers are people who are in charge of designing, building, repairing, maintain different types of vessels overseas. There are many types of things a marine engineer could work on for instance, ships, oil rigs, fixed or movable structures overseas. Marine engineers must know the systems of their vessel or structures and in order to become familiar with the system they create general plant layouts and system drawings. This is important because if anything is damaged or broken it is the engineer's responsibility to fix the problem as soon as possible. Engineers must have the proper knowledge of how each system works and the proper way of keeping system functional. In addition, maritime engineers must test machinery to ensure that everything is up to code and if it is not it must be replaced before any problems occur.[1](U.S. Bureau of Labor Statistics, 2019) Marine Engineers are in charge of doing constant rounds around the vessel engine room to ensure everything is working properly and to document the ships or structures overall performance. By keeping documentation of the vessel or structure it allows the entire crew to have constantly have the same knowledge of what is occurring as time continues.

History

Archimedes is traditionally regarded as the first marine engineer, having developed a number of marine engineering systems in antiquity. Modern marine engineering dates back to the beginning of the Industrial Revolution (early 1700s).

Marine steam engineering

In 1712, Thomas Newcomen, a blacksmith, created a steam powered engine to pump water out of mines. In 1807, Robert Fulton successfully used a steam engine to propel a vessel through the water. Fulton's ship used the engine to power a small wooden paddle wheel as its marine propulsion system. The integration of a steam engine into a watercraft to create a marine steam engine was the start of the marine engineering profession.

Paddle wheel ships

Paddle steamers were the front runners of the industry for the next thirty years till the next type of propulsion came around. Only twelve years after Fulton's Clermont had her first voyage, the Savannah marked the first sea voyage from America to Europe. Around 50 years later the steam powered paddle wheels had a peak with the creation of the Great Eastern, which was as big as one of the cargo ships of today, 700 feet in length, weighing 22,000 tons. The Great Eastern was said to be ahead of its time and was destined for failure. Since the 1800s there have been many improvements to the design of engines and propellers. The maritime industry holds 90% of all international trade.[2]

Diesel Engines

On a ship, the main engine is the beating hart of the ship and often the largest piece of equipment in the engine room. The main job of the engine is to provide power to the propeller which intern gives the ship propulsion. In other words, the ship would not be able to maneuver without the main engine. Although many different kinds of engines have been developed over the years the most common today would have to be the diesel engine.

Although there are many types of diesel engines all operate on the same principals. Fuel is injected into a cylinder which uses high pressure in order to ignite the fuel.[3] This type of ignition system is called an internal combustion engine. The energy that is created by igniting the pressurized fuel air mixtures is exerted on the piston head forcing it down, this motion is transmitted from a reciprocating motion into a rotational motion by the crankshaft.[4] There are three different classifications of a diesel engine: slow, medium, and high speed. This refers to the revolutions per minute (rpm) that the engine is able to put out. Slow speed engines range from 0-300 rpm, medium speed 300-800 rpm, and high-speed engines are 800 rpm and above.[5]

In the maritime industry there are two distinct types of engines, the two stroke and the four strokes. On a ship both require the same five supporting systems in order to operate efficiently; lubrication, cooling, exhaust, fuel injection, and air intake [6] The largest difference between the tow engines would have to be the cycles of each engine. While the four stroke takes two revolutions in order to complete one cycle the two strokes only takes one stroke.[7] Another key difference between the two would be that a two stoke engine does not use an intake valve, instead it has a scavenging port.[8] The more common one of the two would have to be a four-stroke engine due to its better fuel efficiency across a wider range of rpm. One advantage of a two stoke engine is that it is considered simpler due to the fact that it has fewer moving parts, this also allows the two-stroke engine to be smaller and more compact.[9]

Ocean Liners

Ocean liners were the result of the steam engine and new innovations in ship propulsion using propellers. They are passenger vessels designed to transport people by water from one location to the other in a fairly short amount of time. In 1840, Samuel Cunard began operating ocean liners in the Atlantic Ocean and around Great Britain. Eventually, Cunard Lines grew to be one of the biggest leaders of the industry along with various U.S. and French ships. While ocean liners are no longer in demand due to the use of airplanes, in the mid-19th century they were the most prestigious way to travel.[10]

Cruise Ships

Cruise ships took their place after ocean liners began to fade from the industry due to less demand.[11] These ocean liners were repurposed as cruise ships offering amenities, food, and trips to various ports of call. Many cruise lines were founded towards the end of the 1960s and into the early 1970s and had their engineers completely transform ships to better fit the cruising industry.[12][13] Ever since then, cruise lines and their engineers are aiming to have the most innovative fleet of ships and continue to transform the industry.[14]

Cargo Ships

One of two liberty ships that are still operational

Unlike the engineers of ocean liners, cargo vessels transformed from steam to diesel engines much earlier on as they provided more power and propulsion necessary for moving the large loads.[15] These kinds of vessels carry very large loads on board to transport all over the world.

Offshore oil rigs

Marine engineers work on more than marine engines. Marine engineers are also responsible for building and maintaining offshore oil rigs. These oil rigs were first made by Henry L. Williams in 1896.[16]

Important system of a Vessel

Cooling systems

o The Central Fresh Water (CFW) systems on vessels are made up of Main Salt Water (MSW) and the Auxiliary Salt Water (ASW) services. The purpose of having a cooling system is to take heat away from the combustion or friction of machinery that produces heat, for example like the engines. In order to have the cooling system to operate correctly the expansion tanks, heat exchangers and automatic control valve must work.[17](Taylor, 1996) The MSW service is what goes through the engines to cool it down and eventually leave the ship. As for the ASW service, it goes to the air conditioning plant or other ship service.

Propulsion of Ships

o There are many types of propulsion a ship could have such as, steam engines, steam turbines, internal combustion engines, gas turbines, and nuclear reactors.[18](Bureau of Naval Personnel, 1958) These propulsions all of advantages and disadvantages, but the most common is an internal combustion engine. They are two types of internal combustion engines and it is a two stroke and a four stroke. A four-stroke diesel engine is much more efficient at higher speeds because it can produce more power.[19](Machinist's Mate 3 & 2, 1997) While two-strokes engines are used for slower speeds.

Marine engineering specialties

Naval architect

Naval Architects is very similar to Marine engineering, but they focus more on the overall design of the ship. The Architectures worries about the size, weight, and efficiency of the vessel and base the ship structure on safety standards. The reason worry about the specifications of the vessel is because they account for gravity, buoyancy, and stability to affect how the performance of the vessel.[20](U.S. Bureau of Labor Statistics, 2019) Naval Architects create the blueprints of the vessel and then collaborate with marine engineers to layout out the engine room, boilers, ventilations, steering system and many other things on the ship. Before actually building the vessels, Naval architect create prototypes to give other the understanding out how the vessel must be made. Once they are finish with the final product Naval architects test the vessel by putting it through trials on the dock and oversea. By doing this, it ensures that before handing it off to a company they will be able to fix any problems or change the design to make sure it meets the international standards.[21](U.S. Bureau of Labor Statistics, 2019)

Mechanical engineering

Mechanical engineers design the main propulsion plant, the powering and mechanization aspects of the ship functions such as steering, anchoring, cargo handling, heating, ventilation, air conditioning interior and exterior communication, and other related requirements. Electrical power generation and electrical power distribution systems are typically designed by their suppliers; only installation is the design responsibility of the marine engineer.

Oceanographic engineering

Oceanographic engineering is concerned with mechanical, electrical, and electronic, and computing technology deployed to support oceanography, and also falls under the umbrella of marine engineering, especially in Britain, where it is covered by the same professional organisation, the IMarEST.

Offshore engineering

Civil engineering for an offshore environment, the design and construction of fixed and floating marine structures, such as oil platforms and offshore wind farms is generally called offshore engineering.

Challenges specific to marine engineering

Hydrodynamic loading

In the same way that civil engineers design to accommodate wind loads on building and bridges, maritime engineers design to accommodate a ship being flexed or a platform being struck by waves millions of times in its life.

Stability

A naval architect, like an airplane designer, is concerned with stability. The naval architect's job is different, insofar as a ship operates in two fluids simultaneously: water and air. Engineers also face the challenge of balancing cargo as the mass of the ship increase and the center of gravity shifts higher as additional containers are stacked vertically. In addition, the weight of fuel presents a problem as the pitch of the ship cause the weight to shift with the liquid causing an imbalance. This offset is counteracted by water inside larger ballast tanks. Engineers are faced with the task of balancing and tracking the fuel and ballast water of a ship.

Corrosion

The chemical environment faced by ships and offshore structures is far harsher than nearly anywhere on land, save chemical plants. Marine engineers are concerned with surface protection and preventing galvanic corrosion in every project.   Corrosion can be inhibited through cathodic protection by utilizing pieces of metal known as sacrificial anodes. A piece of metal such as zinc is used as the sacrificial anode as it becomes the anode in the chemical reaction. This causes the metal to corrode and not the ship's hull. Another way to prevent corrosion is by sending a controlled amount of low DC current to the ship's hull to prevent the process of electro-chemical corrosion. This changes the electrical charge of the ship's hull to prevent electro-chemical corrosion.

Anti-fouling

Anti-fouling is the process of eliminating obstructive organisms from essential components of seawater systems. Marine organisms grow and attach to the surfaces of the outboard suction inlets used to obtain water for cooling systems. Electro-chlorination involves running high electrical current through sea water. The combination of current and sea water alters the chemical composition to create sodium hypochlorite to purge any bio-matter. An electrolytic method of anti-fowling involves running electrical current through two anodes (Scardino, 2009).[22] These anodes typically consist of copper and aluminum (or iron). The copper anode releases its ion into the water creating an environment that is too toxic for bio-matter. The second metal, aluminum, coats the inside of the pipes to help prevent corrosion. Other forms of marine growth such as mussels and algae may attach themselves to the bottom of a ship's hull. This causes the ship to have a less hydrodynamic shape since it would not be uniform and smooth around the hull. This creates the problem of less fuel efficiency as it slows down the vessel (IMO, 2018).[23] This issue can be remedied by using special paint that prevent the growth of such organisms.

Pollution control

Sulfur emission

The burning of marine fuels has the potential to release harmful pollutants into the atmosphere. Ships burn marine diesel in addition to heavy fuel oil. Heavy fuel oil, being the heaviest of refined oils, releases sulfur dioxide when burned. Sulfur dioxide emissions have the potential to raise atmospheric and ocean acidity causing harm to marine life. However, heavy fuel oil may only be burned in international waters due to the pollution created. It is commercially advantageous due to the cost effectiveness compared to other marine fuels. It is prospected that heavy fuel oil will be phased out of commercial use by the year 2020 (Smith, 2018).[24]

Oil and water discharge

Water, oil, and other substances collect at the bottom of the ship in what is known as the bilge. Bilge water is pumped overboard, but must pass a pollution threshold test of 15 ppm (parts per million) of oil to be discharged. Water is tested and either discharged if clean or recirculated to a holding tank to be separated before being tested again. The tank it is sent back to, the oily water separator, utilizes gravity to separate the fluids due to their viscosity. Ships over 400 gross tons are required to carry the equipment to separate oil from bilge water. Further, as enforced by MARPOL, all ships over 400 gross tons and all oil tankers over 150 gross tons are require to log all oil transfer is an oil record book (EPA, 2011).[25]

Cavitation

Cavitation is the process of forming an air bubble in a liquid due to the vaporization of that liquid cause by an area of low pressure. This area of low pressure lowers the boiling point of a liquid allowing it to vaporize into a gas. Cavitation can take place in pumps, which can cause damage to the impeller that moves the fluids through the system. Cavitation is also seen in propulsion. Low pressure pockets form on the surface of the propeller blades as its revolutions per minute increase (IIMS, 2015).[26] Cavitation on the propeller causes a small but violent implosion which could warp the propeller blade. To remedy the issue, more blades allow the same amount of propulsion force but at a lower rate of revolutions. This is crucial for submarines as the propeller needs to keep the vessel relatively quiet to stay hidden. With more propeller blades, the vessel is able to achieve the same amount of propulsion force at lower shaft revolutions.

Prevention

Cavitation occurs when a change in pressure is found in a liquid which will cause the liquid to turn into a vapor.[27] This can be found on propellers and pumps that are pumping liquids. Cavitation will lead to premature erosion of the propeller and on the impeller of a centrifugal pump. One of the reasons that cavitation is so dangerous is that if this occurs in a fuel line there is a good chance that it could explode. One way to prevent this in a fuel system is to use positive displacement pumps instead of centrifugal pumps. When it comes to preventing cavitation on a propeller you can do two things, slow down the speed of the propeller or increase the number of props.[28]

Career

In 2012, the average annual earnings for marine engineers in the U.S. were $96,140 with average hourly earnings of $46.22.[29]

Industry growth

Marine engineering is predicted to grow approximately 12% from 2016 to 2026. Currently there are about 8,200 naval architects and marine engineers employed, however, this number is expected to increase to 9,200 by 2026 (BLS, 2017).[30] This trend could be attributed to the demand in fossil fuels obtained through offshore drilling and mining. In addition, 90% of the world's trade is done overseas by close to 50,000 ships, all of which require engineers aboard and shoreside (ICS, 2017).[31]

Education

Training Ship Golden Bear docked at California Maritime Academy.

Maritime universities are dedicated to teaching and training students in maritime professions. Marine engineers generally have a bachelor's degree in marine engineering, marine engineering technology, or marine systems engineering. Practical training is valued by employers alongside the bachelor's degree.

Professional institutions

See also

References

  1. "Home : Occupational Outlook Handbook: : U.S. Bureau of Labor Statistics". www.bls.gov (in English). Retrieved 2020-04-29.
  2. Kane, J.R. (1971). Marine Engineering. New York: SNAME(page 2-3)
  3. Taylor, D. (1996). Introduction to marine engineering (2nd ed., rev. ed.). Oxford ; Boston: Butterworth Heinemann.
  4. Russell, P., Morton, T., Jackson, L., & Prince, A. (2018). Motor engineering knowledge for marine engineers (5th ed., Reeds marine engineering and technology; v. 12). London ; New York: Reeds.
  5. • Russell, P., Morton, T., Jackson, L., & Prince, A. (2018). Motor engineering knowledge for marine engineers (5th ed., Reeds marine engineering and technology; v. 12). London ; New York: Reeds.
  6. Bureau of Naval Personnel, (1970), Principals of Naval Engineering, U.S. Government Printing Office.
  7. Taylor, D. (1996). Introduction to marine engineering (2nd ed., rev. ed.). Oxford ; Boston: Butterworth Heinemann.
  8. Brady, Robert N, (1996). Modern diesel technology, Englewood Cliffs, N.J. : Prentice Hall
  9. Russell, P., Jackson, L., & Morton, T. (2018). General engineering knowledge for marine engineers (6th ed., Reeds marine engineering and technology; 8). London ; New York: Reeds.
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  11. "Chapter 7.1 – Cruise Ports". Port Economics, Management and Policy (in English). 2020-02-03. Retrieved 2020-02-18.
  12. "About Us". Norwegian Cruise Line. Retrieved 2020-02-18.
  13. Line, Carnival Cruise. "About Us". Carnival Cruise Line (in English). Retrieved 2020-02-18.
  14. "Executives Biography | Royal Caribbean International". www.royalcaribbean.com. Retrieved 2020-02-18.
  15. "Ship - Cargo ships". Encyclopedia Britannica (in English). Retrieved 2020-02-18.
  16. Bruce A. Wells, (2003) Offshore Petroleum History, American Oil and Gas Historical Society. Retrieved 4/10/14 http://aoghs.org/offshore-exploration/offshore-oil-history/
  17. Taylor, D A (1996). Introduction to Marine Engineering 2nd Edition. pp. 1–383.
  18. Principles of Naval Engineering (1st). Bureau of Naval Personnel. 1958. pp. Washington D.C.
  19. Machinist's Mate 3 & 2. Naval Education and Training Professional Development and Technology Center. 1997.
  20. "Home : Occupational Outlook Handbook: : U.S. Bureau of Labor Statistics". www.bls.gov (in English). Retrieved 2020-04-29.
  21. "Home : Occupational Outlook Handbook: : U.S. Bureau of Labor Statistics". www.bls.gov (in English). Retrieved 2020-04-29.
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