While I know that you will harken back to the "Tillerman" admonishments....

There already is a personal AIS beacon which is slowly being perfected for MOB situations. Obviously you need to stay on the surface and alive -- but with it, a person has a MUCH greater chance of rescue. Those WILL change the likelihood a sucessful recovery.

If my quick artimetic is correct, at 7 knots a boat moves a little less than 12 feet a second. So in a minute you're about 700' from the "victim". ASSUMING that you had control of the boat, you'd be lucky to turn around in 20 seconds -- that's still over 200' away.

Though a paper bag (don't use plastic) over the side at night in a seaway. See how long you can see it. Not very comforting.