Symmetric fixed nozzle for accelerating watercraft on condition of free navigation

摘要

The invention relates to an accelerating nozzle for watercraft in a free navigation condition. The invention provides improved performance in watercraft as a result of the nozzle wherein: the line containing the chord (9) of the contour of the nozzle intersects with the axis of symmetry of the lower cylindrical part of the nozzle, upstream of said nozzle; the difference between the outer radius of the nozzle and the inner radius is between 0.050D and 0.076D, D being the inner diameter of the nozzle; the outer surface (8) of the nozzle is cylindrical; and the inlet edge has a cross-sectional curvature radius of between 0.01019D and 0.004D. The nozzle forms part of a propulsion system which, in turn, forms part of a watercraft.