Yesterday while docking I discovered the boat would not go in reverse. I have the Yanmar 2GM20F engine with a solid 3 blade prop. I went below and checked to see if the shift cable was connected and fully moving the shift lever on the transmission and it was. I also disconnected the cable and pushed the shift lever by hand.It fully engaged in reverse and foward. I observed the shaft to turn both in foward gear and when shifted in reverse. I also did this with the engine up at 1500RPM and the saft was turning fast in reverse but no prop wash??? I can not see how the prop can only turn in foward gear and not reverse. Could this be a transmission problem? The boat is to be hauled this weekend so I can check the prop futher at that time. If anyone has any ideas please post them as I am stumped. Forrest