The young, beautiful daughter(s) of a rich old man (the yachter) who spend their summers tanning on a raft tied behind their
father's luxury
boat (the yacht), or on the bow of
said boat, and who enjoy being gazed upon by young, good-looking lifeguards on the shore.
Lifeguard in tower: Guys! There's a new
boat that just moored out in the cove and it's got a yachter
daughter!
Lifeguard on ground: Toss down those binoculars, we gotta check it out!
Lifeguard in tower: Nah dude, just make the
swim and introduce yourself!