Rotor tests give better than expected results

Paul Gunton

Paul Gunton · 12 December 2018


A German/Dutch project aimed at collecting data on the benefits conferred by Flettner rotors has released details of the first five months operation of the 4,250dwt general cargo vessel Fehn Pollux which was fitted with an 18m high rotor in July this year.

"The data we have evaluated so far significantly outmatch those of our model calculations," said Professor Michael Vahs, who has been researching the topic of wind propulsion for seagoing vessels at the University of Applied Science Emden / Leer for more than 15 years. "In perfect conditions, this prototype will deliver more thrust than the main engine."


15 companies from around Leer have been involved in the development and construction of the sailing system. The whole project is funded by the EU and coordinated by Mariko in Leer. The University of Applied Sciences has developed a purpose-made measuring and control system for this project, which enables scientists to gather transparent and reliable performance data. "For the first time we are able to get precise thrust measurements for a Flettner rotor," said Vahs.

On board Fehn Pollux more than 50 different measurements are continuously collected and computed in real time by the Flettner control system on the bridge. The computer uses the data to calculate the optimum settings for the rotor under the current conditions. The EcoFlettner rotates with a maximum of 280 times per minute but because power is needed to rotate it and full rotations are not required under all conditions an algorithm takes over. In automatic mode, the system adjusts the speed and direction of rotation of the rotor according to windspeed and direction.

"The longer the trial lasts and the more data we get, the more accurate the results will be," said Vahs, "But the data gathered so far allows us to say, that the EcoFlettner saves a noticeable amount of fuel. We are also able to prove, that for ship owners the investment into this sailing system is worth considering, because it pays off in a few years."

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