Maersk opts for energy-saving propellers
Close-up view of the CLT propeller on tanker ‘Roy Maersk’
During 2011, Spanish company Sistemar, part of the Cintranaval-Defcar group, concluded a trial in conjunction with A.P. Moeller – Maersk on Sistemar’s CLT propeller.
The 35,000dwt tanker Roy Maersk was fitted, in November 2009, with a 5.25m four-bladed CLT propeller, in place of the previous 5.65m diameter conventional propeller. The 171.2m length oa ship is powered by a 7,150kW engine turning at 127rpm, for a service speed of 15 knots.
A.P. Moeller – Maersk first became interested in CLT propellers in 2006, during an internal study on different methods of reducing fuel consumption and lowering emissions for both existing vessels and newbuildings. Starting in October 2007, a number of model test investigations were carried out on different type of vessels belonging to the A.P. Moeller fleet to assess the suitability of the CLT propeller design.
The Roy Maersk installation was carried out as a full-scale sea trial on a ship in service, to provide a comparison between full scale results and model test predictions. The full scale exercise comprised pressure pulse measurements and full scale cavitation observations. According to Sistemar, results from the sea trials were encouraging, showing promising efficiency benefits and correspondence between model and full scale pressure pulses and cavitation patterns. As a result of the trials, A.P. Moeller – Maersk has decided to continue its collaboration with Sistemar and to carry out further investigations into possible benefits of using CLT propellers. Current evaluations are looking at other CLT propeller installations, both newbuilding andretrofit.
Sistemar notes that it has experience from more than 275 installations worldwide of the CLT propeller, for which the company claims a noticeable improvement in performance over conventional propellers, demonstrating reduced fuel consumption, higher speed, plus lower noise and vibration levels. In technically and commercially developing the CLT propeller, Sistemar has collaborated with its shareholder company SINM, an Italian engineering consultancy operating in marine, offshore and industrial markets, specialising in naval propulsion, plant design and modification of mechanical key components after failure.
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