I ran into a acquaintance today who bought a new to him 35-36 foot Beneteau this season and asked about how he liked it. He told me it was being repaired and was out of the water all of August. The boat was on a mooring in Oyster Bay, NY (mud and shells on the bottom) and during a lunar high tide and a storm the mooring and boat dragged into another boat causing extensive damage to both.
He was of course upset and talked to the mooring installer ( who was contacted out by the YC he belongs to) and the installer said his boat sailed around the mooring, with the chain wrapping around the keel and that the boat actually lifted the mooring up off the bottom causing the drifting.
He accepted this explanation as the matter was covered by insurance ($17,000).
It doesn't sound right to me--but I never owned a mooring so I don't know.