{"id":102,"date":"2016-11-25T09:47:05","date_gmt":"2016-11-25T09:47:05","guid":{"rendered":"https:\/\/maritimesa.org\/grade-12\/?p=102"},"modified":"2016-11-25T09:47:49","modified_gmt":"2016-11-25T09:47:49","slug":"recent-developments-in-marine-propulsion","status":"publish","type":"post","link":"https:\/\/maritimesa.org\/grade-12\/recent-developments-in-marine-propulsion\/","title":{"rendered":"Recent developments in marine propulsion"},"content":{"rendered":"

SkySails wind propulsion system<\/h3>\n
\"skysails\"

The small freighter Michael A<\/em> with a SkySail rigged ahead. Wind fills the SkySail and helps to propel the vessel. SkySails kites are the key technology for capturing the vast potential of high-altitude winds and SkySails is the first company to succeed in developing towing-kite technology into an industrial application. While the SkySail cannot be deployed when there are headwinds, there is a significant advantage in respect of fuel-saving when using the SkySail with winds from the port quarter, right through to winds coming from the starboard quarter. Photograph: SkySail<\/em><\/p><\/div>\n

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Engine, hull and propeller design<\/strong><\/h3>\n

More efficient engines are key to effective propulsion and therefore to fuel saving that ultimately saves money and promotes anti-pollution measures. The shape of a ship\u2019s hull is important in determining how well she passes through the water in terms of resistance, while the size of a ship\u2019s propeller and the shape of the propeller blades are major factors in determining the efficiency of propulsion. Much work has gone into the design of propellers and propeller blades to improve efficiency.<\/p>\n

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Mary Maersk<\/em> sailing for Asia. She is one of the Triple-E containerships with extremely efficient propulsion system. In the foreground are the jobs of two container gantry cranes. Photograph : Captain Stuart MacAllister Collection<\/em><\/p><\/div>\n

The following is an extract from the website http:\/\/www.maersk.com\/en\/hardware\/triple-e\/the-hard-facts\/efficient-propulsion<\/a><\/strong> and relates to the remarkable design of the so-called Triple-E 18000-teu containerships belonging to Maersk Line.<\/p>\n

\u00a0Efficient propulsion – The Triple-E two propeller system<\/span><\/strong><\/p>\n

The Triple-E ship has greater fuel efficiency due to two-propeller system. Maersk Line\u2019s Triple-E may be the world\u2019s largest container vessel but it is no gas hog.<\/span><\/p>\n

Designing a propulsion system powerful enough to move the ship through the water but with maximum fuel efficiency was a tough task.\u00a0The secret of the vessel\u2019s energy efficiency lies in its custom-designed \u2018twin-skeg\u2019 propulsion system, which uses two engines and two propellers. And the results are astounding: the Triple-E can transport 2,500 more containers than Maersk\u2019s currently most efficient ships (E-class) \u2013 while using 20 percent less fuel and cutting CO2\u00a0<\/sub>emissions by 20 percent.<\/span><\/p>\n

The top speed of the Triple-E was capped at 23 knots, two knots lower than that of E-class ships. This means it has a reduced power requirement of approximately 60 megawatts, a reduction of roughly 25 percent compared to the E-class\u2019s 80 megawatts.\u00a0Setting a lower maximum speed allows Maersk to use engines that can operate at slower revolutions \u2013 the \u2018ultra-long stroke\u2019 engine \u2013 which provides greater fuel efficiency. However, retaining the efficiency created by the slower revolutions of an ultra-long stroke engine re\u00acquires a propeller with a larger diameter.<\/span><\/p>\n

This posed a problem for the designers: the size of the propeller \u2013 which has to be submerged \u2013 is limited by the ship\u2019s draught, the part of the vessel that is underwater. Their solution was to adopt the twin-skeg system.\u00a0The Triple-E\u2019s two propellers are 9.65 metres in diameter, each fitted with four blades, compared to the single propeller of the E-class, which has a similar diameter but six blades. This gives the Triple-E a significant advantage: the combined diameter of its twin propellers provides greater pushing power in the water and the fewer number of blades creates less resistance.<\/span><\/p>\n

The propulsion system of the Triple-E is set to revolutionize long-distance transportation. As a result, Maersk will be able to ship goods on the busy Asia-Europe route with an Economy of scale, Energy efficiency and huge Environmental benefits.<\/span><\/p>\n

Facts<\/strong><\/span><\/p>\n