provided with conventional means e g a flange with threaded holes for attaching a water jet propulsion unit referring again to fig1 the tube portion 8 effectively becomes an extension of the water duct or tunnel 16 i e is in flow communication with the water duct 16 preferably the shape of the tube portion 8 at the inlet where it meets the water duct 16 should conform to the shape of the latter thereby allowing water to flow along a smooth transition from the water duct 16 into the tube portion 8 similarly the inlet to the water jet propulsion unit 18 is in flow communication with the outlet of tube portion 8 thus tube portion 8 of the transom mounting plate 2 guides flowing water from the water duct 16 into the jet propulsion unit one conventional type of water jet propulsion unit comprises an impeller not shown mounted to a drive shaft 48 and a housing 50 surrounding the impeller the impeller draws in ambient water via the duct 16 and the water inlet not shown of that duct formed in the hull bottom 12 the water inlet is preferably covered by a grating or screen not shown to prevent debris from entering the duct 16 thereby avoiding damage to the impeller inside the water jet propulsion unit 18 the impeller housing 50 is in flow communication with a thrust nozzle 52 having a decreasing cross sectional area to increase the velocity of the impelled water passing therethrough a steering nozzle 54 is pivotally mounted to the thrust nozzle by means of a pair of pivot pin assemblies 56 the water flow exiting the steering nozzle 54 can be reversed by activation of a conventional reverse gate 42 which causes exiting water to.