Exactly what I was told by the DNR office.

I found the secondary HIN on my boat when I refinished it this passed spring.  It was under the starboard side rubber bumper at the very back of the boat, riveted in and then the rubber bumper was riveted in also and then the ends covered with aluminum plates also riveted in.  It would take a lot of work to get into it if needed, and then you'd have to know it was there to start with.  

My very first boat, I had this problem with the title, HIN, and all.  The ownerss had the paperwork from being the boat's first owner and all, but it was a 68 model deep V and this was in 96, nearly 30 years old at the time.  Back when that boat was new in 68 they didn't issue titles for boats in KY, only just a bill of sale.  The owner's husband, who really owned the boat, had died previously, and she didn't want to apply for the title in her name so that she could then transfer it to me.  The DMV did their thing with what papers she did have and then we all left.  They told me they didn't know if it would go through or not.  I had to get a pencil tracing of the hull number and send it in with the papers she had.

But the hull number didn't match what was on the bill of sale!!!  So they told me to do another pencil tracing of what was there......and do you know that they sent me a title in my name with that hull number I traced on it!!!!   No further proof was required at all and it only took about a month total to get it.  They asked about that other hull number that was on that bill of sale, but when I told them it was nowhere to be found on that boat, they just changed it to the one that I sent them!!!!

Now that I look back on it, I could have been stealing that boat and would have got clean away with it.  But I wasn't, it was legit, I paid a grand for it.