means of impeller lock nut 21 engaged by thread 23 to the shaft tube 19 to lock said hub in place on said shaft tube an abutment 22 on the shaft tube 19 prevents the impeller hub 12 from moving rearward as the lock nut 21 is tightened a thread 32 on the tapered bushing 20 permits the application of releasing force by means of a release nut not shown against impeller hub 12 to release the tapered bushing 20 and free the impeller hub 12 from the shaft tube 19 so providing a quick installation and release method for installing and removing the impeller 3 the impeller torque is transmitted via 2 or more keys at least one outer key 24 between impeller hub 12 and tapered bushing 20 and at least one inner key 25 between bushing 20 and shaft tube 19 the tapered bushing 20 is oriented to cause the thrust in forward direction f generated by the rotation of the impeller 3 to force said impeller tighter on said tapered bushing in accordance with a further feature there is provided a jet drive with a rotatively supported shaft tube 19 to support the impeller as shown in fig4 said shaft tube is suspended by a forward journal bearing 26 a rear journal bearing 27 and a thrust bearing 28 the rear journal bearing 27 and the thrust bearing 28 provide axial lock up of the shaft tube the thrust force of the impeller 3 is transmitted via tapered bushing 20 to.