Bill,
Yeah the number confused me because I know that there weren't 686 plus boats built. My registration shows the Hull Identification Number like this: TSP000540D686
So maybe the hull number is 540. I think thats the sail #. I'd check the back of the boat but it's late and I've had some wine so I don't want to fall overboard.
From what I've read in the forums, mine may be one of the last few made which is what I expected. I'll confirm this during the day and get back to you. I realize it's good for the class to keep track of the fleet and keep a tally of the the boats that are still in service. Thanks.