Azimuth thruster for ships : Z-drive
(with twin counter-rotating propellers) Steerprop Ltd
CRP

The new dual-end CRP - developed by Steerprop - combines the well-recognized benefits of CRP to those of a pulling propulsion unit.
There are basically two physical features behind the efficiency gain offered by a propulsion unit with contra-rotating propellers:
- First, and most well known, is the aft propeller recovering the swirl energy left behind by the forward propeller
- Second is the splitting of the power not only between two propellers but also between two gear-sets. This makes it possible to reduce the propeller RPM and have two large propellers with light load and low speed of rotation. A combination that yields a very high propeller efficiency. Additionally, also the frictional losses are reduced because of the low RPM.

More specifications...