Abstract: This disclosure relates to a side thruster for a ship. The thruster includes a propeller mounted in a cylindrical tunnel formed on the ship, and a housing-support is connected between the propeller and the hull of the ship for supporting the propeller in the tunnel. The housing-support extends substantially transversely of the direction of water flow through the tunnel, and it is generally elliptical in cross section. At least one enlargement is formed on the outer surface of the housing-support for reducing the effect of K/a/ rm/a/ n vortexes, and the enlargement preferably spirals around the outer surface of the housing-support.