Abstract: An hydraulic propulsion system for watercraft involving the forming of a parallel-sided, open-ended inlet intake tunnel with a recessed intake screen at the rear of the craft, which tunnel directs the incoming water flow into a single or multi-stage cylindrical axial pump having multi-vaned matched impellers and straighteners for driving the flow into an unobstructed acceleration chamber which converges the flow according to the rule of minimal flow losses, and discharges it as a jet through a cylindrical opening with controls thereat to propel and steer the craft. The intake tunnel and the acceleration chamber may be formed of fiberglass, with the former being laminated or molded into the hull of the craft, and the overall system may be of simplified, light-weight, compact construction while producing at least 15% greater thrust than conventional propulsion systems, and much greater thrust than prior hydraulic jets, of comparable power, installed in the same craft.