Propulsion unit

A support strut (21) has an upper end (21A) rotatable supported at a bottom of a vessel and a lower end (21 B) supporting a casing (22). A first electric motor (30) within the casing (22) drives a propeller (50) via a first shaft (31). An annular nozzle (60) surrounds an outer perimeter of the propeller (50) and is fixedly supported on the casing (22) with a support construction (70) comprising at least three vanes (71, 72) extending in the radial direction between the outer perimeter of the casing (22) and the inner perimeter of the nozzle (60). A duct (65) for water flow is formed through the interior of the annular nozzle (60). The propeller (50) pulls the vessel in a driving direction (S1). The vanes (71, 72) are positioned after the propeller (50) in the driving direction (S1) of the vessel, whereby the vanes (71, 72) are optimized for redirecting rotational flow components of the flow produced by the propeller (50) into axial thrust.