The Waterjet drive, basic principles and consequent benefits
Essentially a waterjet drive is like an aircraft turbojet with the difference that the operating fluid is water instead of air. The propelling force is generated by adding momentum to the water through accelerating a specific flow of water sternward.
Water flow from under the vessel is fed through an inlet duct mounted at the transom, flush to the hull bottom, into an inboard pump (the impeller) adding head to the water.
A movable grid is fitted at the duct water inlet to protect the intake. From the pump, the water flow passes through an integrated stator which removes the water swirl generated by the impeller and converts all this pressurized energy into speed, discharging a straight high-speed jet much higher than the boat speed.