Quite a few years ago, I had the use of a Stone Horse sloop in Roslyn harbor that was engineless. I too found it best to sail on a reach to a point downwind of the mooring then turn into the wind and let momentum take me to the buoy. The trick is to gauge the wind strength and adjust the turning point to match. If I was solo, I'd lasso the ball with a line I'd cleated off and then sort things out afterward. That particular mooring field not being very crowded also made things easier.