Sign up
Log in Sign up
Thu 19 Nov 2009, 07:22 GMT

First sea trial of 'fuel-saving' device completed


New product is said to cut bunker costs by improving the water inflow towards the propeller.

Rudder specialist Becker Marine Systems has announced that the first sea trials of its 'fuel-saving' Mewis Duct® device have been completed.

The Mewis Duct® is a propulsion improvement device for full-form ships, ie tankers, bulk carriers and multi-purpose vessels.

The company developed the device after research found that the wake field of full-form vessels, such as tankers, reduces the propeller’s propulsion efficiency. The water flow velocity was found to have such an unfavorable characteristic that the propeller did not get a uniform water flow.

The Mewis Duct® consists of two strong fixed elements mounted on the vessel: a duct positioned ahead of the propeller together with an integrated fin system within. The duct straightens and accelerates the hull’s wake into the propeller and also produces a net ahead thrust. The individual placed fins have a stator effect by generating a pre-swirl in the counter direction of the propeller’s operation, recovering the rotational energy from the propeller slipstream.

Ships are propelled by combustion engines whose power output is dimensioned by the ship’s hull resistance, the propeller efficiency and the desired speed range. The Mewis Duct® is said to reduce the power requirement by improving the water inflow towards the propeller in order to achieve an higher overall propulsion efficiency.

The achievable power savings from the Mewis Duct® are strongly dependent on the propeller thrust loading. According to Becker Marine this ranges from 3% for small container vessels up to 10% for large tankers and bulk carriers.

"The duct combines very consequentially different theories of fluid dynamics. Countless calculations, dozens of tank tests and final true scale tests have proven the enormous fuel saving potential of the product," Becker Marine said.

First Installation

The first installation was carried out at China's Chengxi shipyard. The 46,000 dwt Star Instid runs with a 36sqm Becker Flap FKSR Rudder and was the first of three vessels to be equipped with the new product.

A Becker Service team member was present on site and supervised the installation for Norwegian ship owner Grieg Shipping Group AS.

Following the first sea trials, Becker Marine said the outcome of the first sea trials fully confirmed the predictions from CFD calculations and model tests. Becker Marine Systems has since then installed two further Mewis Ducts®, one of them for Grieg Shipping group and the other for Laurin Maritime. The sea trial results are due to be published soon.

About Becker Marine

Hamburg-based company Becker Marine Systems is a leading manufacturer of high performance rudders and manoeuvring solutions for a wide range of ships. Becker’s rudder systems are used in luxury yachts, super tankers, container ships, passenger ferries and large cruise vessels.

The company’s turnover reached 100 Million Euros in 2008 when over 300 rudder systems were delivered to 25 countries.

Hapag-Lloyd and DSV logo side by side. Hapag-Lloyd and DSV sign 18,000-tonne CO2e reduction agreement for sustainable marine fuels  

Two-year framework allows inclusion of alternative fuels beyond biofuels in shipping decarbonisation partnership.
Bangkok city skyline. Uni-Fuels opens Thailand office as part of Southeast Asia expansion  

Marine fuel supplier establishes Bangkok entity, appoints managing director with 15 years’ industry experience.
Washington State Hybrid-Electric 160-Auto Ferry vessel render. Corvus Energy to supply battery systems for Washington State Ferries hybrid vessels  

ABB selects Corvus for two new 160-vehicle ferries as part of $3.98bn electrification plan.
Vinssen and Mana Engineering sign MoU. Vinssen, Mana Engineering partner on hydrogen fuel cell retrofit for 800-teu feeder vessel  

South Korean and Dutch firms to pursue Lloyd’s Register approval for hybrid retrofit concept.
Hercules Elisabeth vessel. Hercules Tanker Management takes delivery of second Ultra-Spec vessel in China  

Hercules Elisabeth is the second of 10 hybrid-ready tankers designed for alternative fuels.
Wolf 1 vessel. Petrol Ofisi launches fuel supply tanker Wolf 1  

Turkish bunker supplier adds 1,750-dwt vessel with alternative fuel infrastructure to fleet.
BIMCO meeting. BIMCO to convene for adoption of biofuel clause and ETS provisions at February meeting  

Documentary Committee to consider new contractual frameworks for alternative fuels and emission trading scheme compliance.
Sea Change II vessel render. Incat Crowther and Switch Maritime develop 150-passenger hydrogen ferry for New York  

Design work begins on 28-metre vessel with 720 kg hydrogen capacity and 25-knot speed.
Aerial view of a container vessel. HIF Global signs heads of agreement with German eFuel One for 100,000 tonnes of e-methanol annually  

Deal covers supply from HIF’s Uruguay project, with e-methanol meeting EU RED III standards.
Welcoming of Kota Odyssey at Jordan’s Aqaba Container Terminal. PIL’s LNG-powered vessel makes maiden call at Jordan’s Aqaba port  

Kota Odyssey is Pacific International Lines’ first LNG-fuelled ship to call at the Red Sea port.




 Recommended