[Ringz]

When you get a sailing license, you learn that if a man goes overboard, it's best to be (at east) three. One goes overboard, one orders the other never to let the overboard man out of sight and to point with his arm outstretched in his direction, and the boatman uses the outstretched arm to the man overboard. It is impressive how quickly you lose sight of someone even in light waves.

[Kon-Peki]

This is absolutely correct, but is in part due to the complicated nature of getting a sailing vessel to a fixed location in the sea behind the current location of the boat and in such a manner that allows for the boat to be put directly into the wind at the right time to kill forward motion.

[thyristan]

Only very small motor boats are agile enough that you can turn on a dime and not loose sight of a man-over-board. And even then, it strongly depends on wind, current and boat speed. Also, orientation on the seas, sense of direction and getting to a remembered position again is very very hard to impossible. Especially when agitated. You might try using compass and GPS, but those are imprecise, overwhelming and useless when there is any kind of waves or current.

It is absolutely vital to keep the man-over-board in sight. Practically no exceptions.

[closewith]

That's the drill for all vessels, powered or not.