Define yacht then

Edit: oh, it seems, the American English strikes again

As per UK definition I’m accustomed to, a yacht is:

a boat with sails and sometimes an engine, used for either racing or travelling on for pleasure

While the US definition is:

a large and usually expensive boat, used for racing or for traveling around for pleasure

Although this, too, doesn’t rule out a yacht not necessarily being expensive, and don’t really say what’s large in actual size