Sometimes a boat can be built one year and registered as a later year - this happens sometimes when a boat is sold in a non-title state in the year after being built. You get a bill of sale, not a title, no often it may not be tied to the HIN. If the boat is titled later, the title agency often uses the original bill of sale for the year model. So a '86 could be listed and even titled as an '87 if it was sold in '87 in a non-title state. Also, sometimes the manufacturers will keep a couple last year stock around until the following year and sell them as the following year model if there are no changes in the next model year. I had a Procraft that I bought new in 1980 that had a 1979 HIN, but was sold as a 1980 model and had a 1980 title. When I questioned it, the dealer said some '79s were "kept over" at Procraft and sold at '80 models. There were no changes in the design or manufacture between 79 and 80, so what's the diff? But it never seem quite right to me... Also, like cars, sometimes the next model year comes out in the fall of the previous year. So you can buy a 2011 boat now, but it's going to have a 2010 HIN, cuz it was make last week. The boat may be a 2011 model, but with a 2010 manufacture date.