My propeller shaft makes a rapping noise when I motor over 4.5 knots. It sounds like the shaft is hitting against medal. If I apply a slight upward pressure on the hose just aft of the packing joint the rapping will quit.It started when I bumped a rock on the bottom as I was turning out. I did not hit hard but afterward the rapping started.I had the shaft aligned and repacked.Anyone got any ideas what it may be and how to fix it.Don