a few thoughts
w/o knowing all the facts (real or percieved)..consider a few points.
the boat may be documented, thus no numbers on the hull..they could be down below in a conspicuous place.
this guy may be going through a divorce, and trying to hide assets from spouse.
that additional amount of income might also affect child support or his income tax bracket.
these were the first things that came to mind..
or the guy may just be weird..or dishonest (as in make sure you see something resembling a title)
i'd rely on "gut check" to be the last filter..does this transaction make you feel warm and fuzzy..if not think about passing on it.
By three methods we may learn wisdom: first, by reflection, which is noblest,second is by imitation, which is easiest,third is by experience, which is the bitterest.
Sanctuary, Sabre 30 mkIII