Refers to the old freestanding type bathtubs that look like giant oval shaped bowls in the corner of the bathroom. Bathtub type boats appear to sit on top of the water just like bath basins sit atop the floor in a bathroom.
Refers to 99% new boats on the water today. Purchased by suburban yups that know nothing about boats. Such boat buyers tend to equate boat size with boat quality and consequently buy the cheapest, biggest barge that they can locate.
"Look at that bathtub my neighbor just bought.