My 1983 200 mariner will only push boat in idle both forward and reverse. I was going at normal speed when boat acted like I lost prop I checked it was still there the boat would move in idle but when you Rev up engine it would not move. Prop does not have a sheer pin and prop nut seemed loose so I tighten it to proper torque and this did not take care of problem. Motor seems to run fine no noises it just doesn't push boat
