Sprint boat racer's worst nightmare...
 

This happened in Port Angeles, WA this past weekend. Both driver and navigator got out unharmed due to the ultra-quick response from the safety crew.

Wow, I'd say the nightmare is the course itself.

What does the "navigator" say? "Left now! Right now! That hot chick is flashing you, 2 o'clock!"
Seems like a superfluous position for a speed boat...

Different teams use the navigator to different levels. As the driver, I absolutely, positively HAVE to know the course cold. The rotation happens so fast, there is no way to just rely and react to the navigator. We use hand signals primarily but will more than likely be going to an intercom system next season. If you're going down a channel and you take the 2nd turn…my navi holds out a big 2 fingers for me….if we circle around the outside…she does a looping motion. I don't look over to see her but pick a few of the signals out of my peripheral vision. If you look down, you're going to hit a bank!