Bad news Charlie, sorry mate.
However this doesn't sound like the damage we have heard of late, they wouldn't have been trying to steal it, so I'd suspect a collision that wasn't reported whilst on your mooring?
Twice this year I've had to swerve to avoid yachts coming out of PYC who appear to have been out if control and have ended up grounded in the shallows not far from where Alfresco moors.
Do you have CCTV covering the approach to the Marina?