The present invention's nozzle is especially suitable for use in a shipboard air-discharge maneuverability device known as a “bow thruster.” As typically embodied, the inventive nozzle includes a nozzle wall and an arc-shaped vane. The nozzle wall has a circular nozzle inlet and an elliptical nozzle outlet, and is configured so that the geometric major axis of the nozzle outlet is horizontal. The arc-shaped vane: is upwardly bowed in the nozzle wall's transverse direction; joins the nozzle wall along its two horizontally opposite sides in the nozzle wall's longitudinal direction; extends most or all of the longitudinal distance between the nozzle inlet and the nozzle outlet; has a transversely intermediate section that, taken in the transverse direction, is generally uniform in thickness; has two transversely lateral sections that, taken in the transverse direction, gradually thicken toward the two respective joints of the arc-shaped vane with respect to the nozzle wall.