Having a large boat for recreation (rather than work, like fishing) is sort of a cultural symbol for wealth (in the USA, anyway).

The California Lottery's current TV spot shows a youngish guy on a yacht, with a pony.

It's perhaps inspired by the old Lyle Lovett song, "If I Had a Boat", which says:

  "If I had a boat
  I'd sail across the ocean

  and if I had a pony
  I'd ride him on my boat."