Abstract: A hydraulic system for the control of boats, ships and crafts in general that comproses nozzles (1, 2) opposed and the end of the stem, having a Venturi tube throttling (8) or an internal diameter reduced by means of flanges (10), so as to be able to determine, following to the outlet of the fluid under pressure, the movement by reaction of the front part of the boat (N) and therefore to perform immediate leftward or rightward curvings according to the nozzle used, and/or corresponding nozzles (3, 4), placed nearby the stern and with similar background function, while the operating the hydraulic reaction of both nozzles placed on the same side determines the parallel movement on the whole craft, for moming alongside to quays or for performing other maneuvers.