Pretty much. When the humming starts, try lowering the keel and give it another turn to give it some slack. IMHO the noise appears to be similar to a blade of grass vibrating in your hands while blowing air past it like we all used to do as kids or like a violin string vibrating. You have 750 lbs pulling that steel cable taut and that's a long surface, that with the right circumstances, such as moving through the water, will make it "sing". Are you able to let the keel down all the way where you sail? I have never locked mine down since I sail in the Chesapeake and it's tributaries which can get into really short water really fast...