Abstract: The assembly includes a nozzle adapter rotatably mounted via a pair of axles onto a jet nozzle of a personal watercraft. A hinge rotatably connects a rudder and cap onto the nozzle adapter. A torsion spring on the hinge retracts and retains the rudder and cap in a position in which the rudder extends below the nozzle and nozzle adapter thereby positioning the rudder in the water below the watercraft to provide steering capability to the watercraft. The cap covers and blocks the nozzle outlet when the engine is not operative but when the engine is operative the jet stream forces thereof acting against the cap rotate the rudder upwardly so that it extends rearwardly from the watercraft and out of its steering position. The nozzle adapter includes an inner adapter attached to the nozzle and an outer adapter attached to the inner adapter.