Was that kayak stolen?

[kayakwriter]

You can search for boats by their Hull Identification Number here to see if they've been reported stolen. Since 1982, manufacturers in Canada and the States have been required to put one on all their boats. On kayaks, it may be stamped or engraved at the stern, usually near or on the line where the hull meets the deck. On many British-made kayaks, it's glassed into the hull on the inside, beside or behind the seat. A missing or obscured HIN is like a missing VIN on a used car - a good reason to be highly suspicious.

BTY, the last two digits of the HIN are the year of manufacture of the boat. So for example, a boat with the number VSK1713D515 was made in 2015.

 

[JohnAbercrombie]

the last two digits of the HIN are the year of manufacture of the boat. So for example, a boat with the number VSK1713D515 was made in 2015.

Not exactly - in your example it is true, but:
D= month of manufacture (April)
5 last digit of year of manufacture
15 last two digits of model year - usually the first year that design was produced.

So the last 4 characters could be D512 for a 2015-manufactured boat first produced in 2012 in some cases (see below).

But in practice HINs aren't always standard (or even present- my wife's 2011 NDK Romany had no HIN marking).

Here's another example, from correspondence with Matt Broze (Mariner Kayaks):
Red Express:
We delivered it in 6/3/1995 and from the serial number MSQ32140E591 you can see it was built in E=May of 5=1995, The 91 at the end then meant to us the model first came out in 1991 but later the Coast Guard clarified that to mean the "model year" like cars (and apparently bigger boats) use so once that was clear we just repeated the year of manufacture with the last two digits. It was the 140th Express made and the 32 was our code for an Express, The MSQ was the code the Coast Guard assigned us after we had requested MSK when we first signed up with them in 1982.
Red Express
MSQ
32 Express code
140 # in Express production
E Month=May
5 1995 or 2005 or even 2015 if Mariner hadn't closed the business in 2007
91 First Express made