Tunnel Thruster is a system with the purpose of manoeuvring the bow or the stern of a vessel sideways and to allow agile movements in even the most restricted areas.
The propeller that generates the thrust is powered by an electric motor, hydraulic motor or diesel engine via a right angle gearbox. The driving parts are assembled as a system by means of a tunnel structure which can be located in the bow or stern part of the ship’s hull.
Possibility for flexible installation to reduce vibration.
Fixed pitch single propeller
Controllable pitch single propeller
link:
https://www.thrusterleader.net/tunnel-thruster1/