Feature 4 | ALTERNATIVE PROPULSION


and direction, and that periodical savings of up to 50% will be attainable under optimal conditions. “Our own measurements show that we were able to temporarily save far more than half the fuel by deploying SkySails in favourable wind conditions,” reported Wessels’ managing director Gerd Wessels, adding that: “Alternatively, we were able to increase the ship’s cruising speed from 10 to 11.6kts with the help of this towing kite propulsion.”


Programme agenda Pilot testing of the technology is set to continue aboard the Michael A and also the larger, heavy-load multipurpose vessel Beluga SkySails, until early 2009. The programme entails an initial focus on calibration work and technical modifications, so as to stabilise the towing


kite propulsion, followed


by concentration on extending the flight times and optimising system performance. Another facet of the trials is the evaluation of a sea-state compensator integrated within the SkySails system, intended to allow the kite to be launched in more difficult weather conditions. Target markets include trawlers and


super-yachts as well as cargo vessels, and systems with kite areas of up to 320m2


are


planned. Besides newbuild applications, the technology lends itself to retrofitting of virtually all cargo ships. The fuel-saving attributes of the concept translate into substantial environmental benefits in lessened emissions of CO2


. Testing of the automatically-


controlled SkySails kite system and the associated, OceanWaveS-developed wave monitoring arrangements on Beluga SkySails is being conducted under the auspices of an EU co-funded project known as WINTEC (wind propulsion technology for cargo vessels).


Commercial use Meanwhile,


the John Walker-headed


firm Shadotec is working closely with


two Oslo-based companies,


Wi lhelmsen Marine Consultants (WMC) and Petroleum Geo-Services (PGS) to examine the potential of wingsail propulsion for commercial


46


shipping. Backed by funding from the Norwegian Research Council, the study consortium has commissioned Trondheim-based CFD Norway to estimate possible savings in fuel and reductions in exhaust gas emissions attainable by using Shadotec wingsail units as a propulsion assist device. Technology research organisation Marintek, also of Trondheim, is to contribute its know-how by evaluating manoeuvrability and seakeeping. The initial task of


the Norwegian


research project has been to investigate the feasibility and potential of fitting two fully-automatic, computer- controlled Shadotec wingsail thrust units on a highly sophisticated seismic exploration ship. The subject vessel, one of the 102m Ramform- type units run by Oslo-based PGS, is distinguished both by its arrowhead-


“Besides newbuild applications, the technology lends itself to retrofitting of virtually all cargo ships. The fuel-saving attributes of the concept translate into substantial environmental benefits in lessened emissions of CO2


.”


like bow form and by its multiple array of hydrophonic streamers, necessitating a considerable power concentration of some 30,000bhp. Analysis by CFD Norway indicates that


the Ramform vessel equipped with two Shadotec wingsails, and towing a typical deployment of streamer assemblies at its standard speed of 5kts in characteristic


North Sea wind conditions, could save more than 5% in fuel consumption. Savings could be as much as 10% with the sails deployed when the ship is running free, with the cables wound in, on passages between seismic survey assignments. Presently fitting out at the Lindenau


yard in Kiel is a vessel that has been purpose-designed for Enercon’s worldwide transportation of wind turbines and components is set to revive a sailing rotor technology first employed more than 80 years ago.


Field of application At 130m length and 10,500dwt, E-Ship 1 is somewhat outside the compass of Ship & Boat International, but her remarkable sail system has a potentially broad field of application. Four 25m-high, rotating, vertical metal sailing rotors, two arranged forward and two aft, are expected to cover a large portion of the ship’s propulsion energy needs, supplementing or complementing two 3500kW main engines. The sailing rotors were developed by Enercon engineers, drawing on the concept encapsulated by the original Flettner rotors, used in the 1920s on the refitted schooner Buckau. Named after their inventor, Anton


Flettner, the rotors harness the so-called Magnus effect, first demonstrated in the 19th century by the German physicist Heinrich Gustav Magnus. A spinning cylinder in a moving airstream creates a lateral force perpendicular to the direction of the airstream, channelling the wind in such a way as to generate a lift force. By adjusting the rotor speed, the amount and direction of the lift can be tuned to the desired course and wind direction to create forward thrust. SBI


Ship & Boat International November/December 2008


Beluga SkySails Projects vessel (copyright: SkySails GmbH & Co KG).


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