As part of its major conversion to burn LNG as a fuel, 1986-built ferry Münsterland is getting a propulsion makeover, too, with the addition of two counter-rotating, integrated electric drives
Owned by German ferry operator AG-Ems, the conversion of MS Münsterland is being carried out at Niestern Sander Shipyard, where the 90-m ferry is being fitted with a new bow and stern, with the latter incorporating dual-fuel engines, LNG storage tank, pipes, systems and propulsion.
For the conversion, Veth Propulsion is supplying two counter-rotating, electric Veth integrated L-drives and one two-channel bow thruster. Veth points to the extreme compact nature of the L-drives due to the permanent magnet (PM) motor mounted on top, as well as the units’ low noise and high efficiency levels.
Speaking at Riviera’s Propulsion packages: the full package? Propulsion packages critically assessed webinar in February, Veth Propulsion product manager for thrusters Bastiaan van Zuijlekom described the advantages of the company’s integrated L-drives, one of which is the much lower mounting height.
For example, Veth offers two similar 550-kW rated propulsion drives in different designs. Its VL-550 is 3,500 mm tall, of which 2,450 mm is the drive motor. But its VL-550i is 1,600 mm tall with just a 410 mm high motor.
“We integrated the permanent magnet motor in the thruster top section,” said Mr van Zuijlekom. “This is an optimum-shape pod with no vulnerable motors or planetary gears under water.”
Veth said the PM motor was designed in collaboration with Finnish electric solutions provider Visedo, part of Danfoss. On average, a PM motor is 40% to 60% more compact than an asynchronous motor. Additionally, the integration of the PM motor into the thruster makes them very compact, when combined with the special mounting method, the alignment of the headsets and the adjustments to the control box.
“There are no sliprings, no main motor, flexibility in positioning, just one gearbox, and no high-frequency underwater noise and the permanent magnet motor has optimised rpm,” said Mr van Zuijlekom.
These technologies reduce capital expenditure on the main engines and generators and provide solutions to ship design challenges. “Develop solutions instead of just propulsion,” said Mr van Zuijlekom. “Develop ships instead of just solutions.”
Since the Veth integrated L-drive is diesel-electric driven, it is significantly quieter than a mechanically driven drive, adding to the comfort of the crew and passengers. Features such as the water-cooled PM motor and electrical control underpin the Veth integrated L-drive’s ‘silent’ nature.
In the case of Münsterland, modifications to the design of the ship’s stern enabled the positioning of the thrusters to be optimised. Niestern Sander incorporated lessons learned from the AG-Ems ferry Ostfriesland, which was converted by another shipyard in 2015. “Munsterland’s aft is a derivative of the Ostfriesland stern, where improvements have been made that have resulted from hydrodynamic tests [that enabled us] to better determine the position of the thrusters,” Niestern Sander sales manager Ben Veenstra said. “From the previous AG-Ems LNG retrofit we learned we could realise a smarter concept of propulsion by switching from two gas engines to just one. That was also of considerable benefit to the implementation of the entire conversion.”
Funding for the conversion is being provided by Germany’s Federal Ministry of Transport and Digital Infrastructure as part of the implementation of the Federal Government’s Mobility and Fuel Strategy.
Besides Ostfriesland and Münsterland, AG-Ems operates 2015-built, gas-powered ferry MS Helgoland, making it a frontrunner in adopting LNG as a fuel.
Riviera’s Marine Fuels Webinar Week will begin 8 March 2021 - use this link for more details and to register for the free 45-minute webinars