While thrusters are a frequently used concept for the main drive in inland navigation, in the maritime sector they are mainly used as auxiliary drives. Thrusters hold a ship in its position very well, and even more important, they also enable quick reactions to swell and wind effects.
A thruster combines propulsion and steering in a single device and is able to rotate 360 degrees. Therefore, full thrust[ds_preview] or traction of the propeller is available in each direction while a classic rudder only enables to change course but not contribute to the drive of the vessel.
In a rudder propeller the main engine is usually mounted in the hull of the ship. This is the main contrast to pod drives, where the electric drive unit is submerged in a gondola through which the propeller is rotated.
Rudder propellers are often provided with a nozzle pivotable by 360 degrees likewise, and are distinguished further: There are a so-called z-drive or l-drive thrusters, the former is the classic version, invented 1950 by Joseph Becker, the founder of Schottel in Germany.
Here the motor shaft and propeller shaft are arranged in parallel levels and are connected to each other via a bevel gear and a shaft perpendicular to their shafts. The advantage of the l-drive thruster, which is available as an electric motor or hydraulic motor, is the significantly shorter length. Another factor is the propeller diameter.
The larger the diameter, the more draft is needed for the vessel. The installation of two propellers, so-called twin propellers may increase the drive power without increasing the propeller diameter.
Additional implementations include extendible and retractable systems. Experts consider these to be compact and reliable. Anchor handling tugs and offshore supply vessels commonly use this technique. In addition, there are counter-rotating propellers. The advantage here is the twist-free outflow. As a final result there is less resistance to flow.
Friedrich Wirz from the Technical University of Hamburg-Harburg (TUHH) predicts there is future development potential for thrusters – especially with respect to efficiency. Efficiency gains could be achieved for example by optimizing the wings and nozzles. The expert believe there is further potential even at non-hub drives. Such compact small angular gears feature electric motors integrated into the nozzle. Thus, the influence of »disturbing parts« would be kept as low as possible. In total Wirz does not assume that the scope of the thrusters will change.
The following market overview presents products from different suppliers in alphabetical order. The informations came either directly from the suppliers or have been gathered trom their websites or brochures. M
Thomas Wägener
