Smacky, I think a better metaphor would be "dinner and a movie"
Oh, see GregS - now you've done it! So, sailors, what are all the metaphors for sex on a boat?
As for the noise, privacy, etc. - who gives a damn? If some prude doesn't like the ruckus, he can either pick up another ball (heh-heh) or score another slip (heh-heh) out of range, right? Right.
Let's raise our mugs to sex on a boat!