My Alpha drive makes a knocking sound (it can also be felt in the hull) that It hasn't done before. I have owned the boat 10 years. On land on muffs, when put in forward or backward gear a knocking sound appear as heard on attached file. Does anybody have an idea what it could be? I have been told its probably because there is no load on the propeller, but as said, it haven't done that before. The mechanics I've spoken to don't have time for another month or so.
