This is a longshot, but maybe worth a try. A water ski racer by the name of Rick Lathrop used to practice almost daily at Carlsbad Lagoon back in the late 1960s and early to mid 70s behind his dad's (Fred) V-drive flatty. Fred actually ran the marina concession at Carlsbad for a long time. If anybody during that era would have sunk a boat at Carlsbad, Fred or Rick would have probably known about it. Rick is now living in Lake Havasu and last I heard had a swimming pool cleaning service. Sorry, I don't have a current phone number. You might try contacting the National Water Ski Racing Association for a contact (www.nwsra.net), Rick's daughter Ashley entered a few races earlier this year. Good luck.