Bow thruster
From BAWiki
Definition
A ship’s propeller (standard model) that accelerates water in a tube in the bow section orthogonal to the axis of the vessel. It exerts a transversal thrust that acts in the same way as a rudder. It is most effective at low speeds over ground.
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Source
Glossary of Coastal & Hydraulics Laboratory (CHL), US Army Corps of Engineers (USACE), Vicksburg, USA