If you can get the storage yard operator to give you the name of the owner I would contact him and see if he is interested in selling it. Before you call I suggest you get some idea of the market price for this boat, deduct a big discount for buying a 'pig in a poke' and only pursue it if you can steal it. If the boat is badly neglected in storage how would it have been treated for regular manitainance and while it was in the water?
I also love to get a deal but don't buy a bunch of headaches. You may want to make a purchase conditional on a ride with a qualified marine mechanic along.