If you have a title with a HIN number, use that, and don’t lose it. Why are you questioning it? Your state calls for a title, and you have one. The state motor vehicle department – or whatever department handles boat registration – may have made up the HIN number for their own reasons when the previous owner showed up in 1995 to register the boat for the first time. Who knows? For racing, the Lightning Class Association does not care what the HIN number is. They go by the sail number, which you say is also on the centerboard trunk. If you’re still hung up about it, write the HIN number from your title on the underside of the foredeck in black sharpie letters 2″ high. Go sailing and don’t worry about it.