The Mewis Duct® has proved to be very successful for large and slow speed ships like bulkers and tankers. Instead, the Becker Mewis Duct® Twisted (BMDT), formerly known as Becker Twisted Fin® (BTF), was developed for ships, which are faster than container vessels.

Like the Mewis Duct®, the Becker Mewis Duct® Twisted has no movable parts, is installed in front of the propeller as well and generates a pre-swirl. The nozzle ring is significantly smaller than that of the Mewis Duct® and has specially-developed thinner profiles which significantly reduce drag. The fins familiar from the MD on the inside of the nozzle ring extend outwards beyond the nozzle. The fins are both tapered and twisted with modifications to the free outer fin tips. The cavitation risk has been minimized by these measures.

Computational Fluid Dynamics (CFD) calculations and model tests after 15 test series have shown fuel savings averaging about 3.2 % for container ships.

For more information see the publication No 50.

Short history:

  • September 2012: patent pending
  • October 2012: first model test
  • December 2012: first installation in full scale
  • November 2015: 50 BMDTs are ordered

Becker Marine Systems in Hamburg is marketing and selling the Becker Mewis Duct® Twisted exclusively.
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