Ship Propulsion Systems: the Options - Essay Example

Ship propulsion systems: the options Introduction There are various types of propulsion systems that are used in ships. The design of the propulsion system to be used on any ship is dependent on the requirements of the vessel (Harvey, 2007 pg 55). In determining the options that are there in the ordering process of the four tankers, it is essential that this paper first looks at the basics of propulsion. This will aid in weighing out the technology that will be efficient and with minimal controversies. The paper will look at the various propulsion technologies and value their pros and cons based on various factors. The choices will seek to establish an option that will be safe to the environment and reduce the controversies arising from stakeholders; also put the company in a relatively competitive commercial position. Ship’s propulsion system A ship’s engine is connected to the propeller through a shaft. The combination of this system and other essential machineries make up the propulsion system of the ship. There are various factors that determine the propulsion system to be used in a ship such as the speed requirements, required power and the type of the ship amongst others. The types of propulsion systems have been changing with time since people started the shipping industry (Biran, 2003). This paper will try to bring out the various available options in the selection of a right propulsion system to be used in the four tankers. The paper will look at the available propulsion systems and modes in which they can be selected. Direct drive propulsion This has been identified as the most common used system of propulsion. The arrangement of the engine in this system is basic. In this system, the propeller is connected to the main engine using a shaft (Bright Hub 2011). This makes ships made using this system to move at slow speeds. Maneuvering ships with this system is done by regulating the speed of the main engine. This, in turn, causes the direction of rotation of the propeller to change and thus reducing the acceleration of the vessel. This system was the first propulsion design created, and thus was used in almost all ships in the earlier days. There have been improvements performed on the direct drive propulsion. These improvements have been done with the aim of increasing the speed of vessels. In modern times, the use of direct drive propulsion has been reduced to ships plying zones with speed regulation. Geared drive propulsion Geared drive propulsion system has been extensively adopted as an option to the direct drive propulsion. The engine is fitted with gears to offer support function. Gearing is done for two main purposes. Firstly it helps the revolutions by the engine and effectively improves the output of the engine (Salter, et al 2008). This ensures that the efficiency of the propeller is utilized to the maximum. Secondly, gearing enable two shafts in the same engine to share power. This allows engines to have extra output by using double shafts in the same engine. The increased engine power gained by gearing helps increase the speed of a vessel. In this system of propulsion, reversing becomes easier than in the direct drive propulsion. Easier reversing eases the function of controlling the direction of a vessel. This system has been extensively used in the modern day prime movers as it offers improved speed and simpler control of the vessels. Electrical propulsion system This system was extensively employed in ships during the Second World War (Friedman, 1995 pg 260). This system combines the use of a large gearbox along with an electrical drive. High speeds have been achieved in modern times through the use of this system. The system extensively reduces the noise produced by the first two propulsion systems. The speed of vessels is also drastically increased by the use of the electrical drive. Ships with this system of propulsion are, however, expensive to manage. The system has a low mechanical advantage; therefore, the engine consumes a lot of fuel. The advantage of this system comes in the fact that the system can utilize low grade fuels(Stopford, 1997) This creates a cost efficiency balance for the high consumption of fuel making the system affordable to many organizations. The system also has the capability to centralize the source of power in a vessel. Other functions of the ship can be powered by the same source powering the engine. Factors to consider There are numerous factors to consider when choosing a propulsion system for these for tankers. The most efficient system has to be able to fit within the description of the desired standards. The numerous factors to be considered in the installation of a new propulsion system are discussed below. These factors are based on the performance of the previous system (Drouin, 2006). They seek to improve on the performance of the previous system while maintaining conformity with the arising issues of carbon emissions. Speed The tankers shall be used for commercial purposes and quick delivery of goods shall be essential. The ships need to have a capability to move faster than the previous vessels so as to increase the business rate (Andersen, 2008 pg 15). The use of geared drive repulsion would ensure that desirable speeds are achieved by the vessels. The tankers shall be able to make numerous trips within the specified route when their speed is increased. The route in which they shall be plying does not have speed regulation. This will ensure that the vessels remain in conformity with the regulations regarding speed. The vessels have a dead weight of about 180000 tones which is quite large. The new engine system is supposed to cater for this weight without being overworked. While the use of direct drive propulsion may efficiently handle this weight, the speed of the vessel would be immensely compromised by the system. The inclusion of gears would cater for speed and the weight of the ship without much strain on the engine. Though electrical propulsion system can also be equally sufficient, the cost of fuel to run the system may come as a hindrance to the use of electrical propulsion. Power The vessels under construction are tankers for transporting fuel. The power needs for these vessels are not as surmountable as those of ships with other functions. The geared drive propulsion system would be sufficient to power the engine. The majority of the power consumed by these vessels will be by the engines (Lewis V, 1989). The other functions like lighting shall be powered by independent generators fitted in the vessel. The geared drive propulsion in this case seems enough to suffice the power needs fro each of these vessels. Installation of the electrical propulsion system can provide enough power to for the vessels. This system, however, would produce more power than the requirements of the vessels (Gilmer, 1975). The extra power produced would go to waste as there would be no system installed to store the extra power produced. The electrical system produces enough power to use in other functions of the sip. These vessels have considerably few of the other functions which might make proper use of the power. It would, therefore, be a waste of resources to use the electrical system in these vessels. The economical sustainability of the electrical system would be questionable in the case of these vessels. The cost or running an electrical system would not be in line with the ship functions. Type of ship The types of ship under discussion are tanker. These ships usually ferry crude oil and other oil products across various zones (Hourani, et al 1995, pg 91). The tankers shall be expected to move at moderate speeds while performing their main functions. Since their functions are limited, the rate of tearing and wearing of the engines shall not be high. While electrical system reduces the costs of maintenance drastically, these vessels shall not require much maintenance as their functions are limited. They shall only serve the purpose of transport and no other functions. The vessels do not have loading cranes or other such machinery. The use of geared drive propulsion shall be sufficient for the purposes and functions of these vessels. Arising issues Numerous issues concerning the control of the rates of emission have become an issue of concern. Engines running on petroleum fuels have been identified as causing adverse pollution effects on the climate. Reduction of these emissions has been at the centre of new technologies. Regulations have been put in place control the amount of emissions produced by machineries. These vessels may be contributing to these issues if the use of petroleum related fuels is continued. In modern maritime operations, other types of ships have adopted the low carbon emission systems (Huber, 2001). Almost all cruise liners nowadays use systems with low carbon emission. Though the ships under discussion are tankers, the trend has been set in the maritime industry to reduce emissions into the ozone. The adoption of these systems would, therefore, be of significant importance towards keeping up to date with the current maritime trend in use. Almost all governments in modern times have imposed regulations concerning carbon emissions into their territories. These regulations apply equally to all machine emitting gases. It is, therefore, essential for these vessels to be compliant with the regulations of carbon emissions. The emissions have been an issue of concern among several environmental organizations. The growing effects of global warming can be attributed to the carbon emissions by machines (Edwards and Miller, 2001). The failure for these vessels to comply with the emission regulations might pose serious repercussions on their operations. The ship my not be allowed to dock in some ports until they reach a time when they comply with the regulations on carbon emission. Such a scenario would adversely affect business for the company since these vessels are commercial. It is, therefore, essentially for these vessels to comply with all regulations regarding environmental pollution. Recommendation The new vessels should be fitted with electrical propulsion system. This will enable the vessels to reduce the amount of emissions from the engines. Though the system may be expensive to run, several cost cutting methods are going to be adopted with the aim of maintaining a sustainable environment. The vessels are going to maintain the use of low grade fuels available. This will enable the vessels to cut the cost of fuel while maintaining the required environmental standards. This system can be characterized by low maintenance cost. Since the system has few, movable engine parts, the maintaining costs are drastically low when the system is in use. When the economics of scale are applied, the low maintenance cost will cater for the extra fuel consumed by the vessels (Hayler, et al 2003). This works to create a balance on the financial implications of the electrical system. The vessels can be fitted with some extra facilities to consume the power produced by the electrical system. These features would play a crucial role in improving the comfort of the crew (Turpin, et al 1980). It would also ensure that the excess power produced gets utilized. Optionally the system would be used to power all the functions of the vessel. This would ensure that there is maximum utilization of the power produced by the system. An electrical system would ensure that the pollution issues raised become adequately addressed. The other two methods previously described all show high levels of emissions than the electrical system. This can be said to be the most environmentally sustainable innovation into the maritime engineering industry. The system does not have many engine parts to sustain (Evangelista, 2002). This would make the vessels easy to dispose once their use comes to an end. Many of the parts used in the electrical system are recoverable, and this would ensure cheap disposal of the vessels in the future. The combination of these factors eventually makes the electrical system to be financially viable in the long run. It is, therefore, inherent for these vessels to be fitted with the electrical propulsion system. Conclusion Maritime engineering has experienced tremendous change since its inception. The aspect of propulsion can be termed as an essential issue of concern in the construction of sea vessels. The enormous sizes of these vessels have made them be identified among causes of severe carbon emissions to the environment (Sullivan, 1978). There has been a growing desire in the maritime engineering sector to improve the performance of these vessels. These improvements have, however, been met with a growing concern for the global environment (Gore, & Steffen, 2008 pg 265). Regulations have been set to govern the rates of emissions within the global environment. These regulations have necessitated the need for maritime engineering to consider the emission caused by vessels when constructing them. Numerous inventions have been made in the effort to keep up with the growing pressure from the environmental protection agencies. References Andersen, Erik M. (March 2008). "The Tanker Market" The Platou Report (Platou): 14–18. Biran, Adrian; (2003). 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