wow
anything special for night time?
Short answer: Don't fall overboard at night. Encourage / urge the buddy system for passengers and crew on deck at night.
Long Answer: Man overboard at night is obviously the worst. Most vessels, large or small, are often
not fully prepared for a Man Overboard at night or in low-light conditions. By prepared I mean ready to
immediately drop a life ring or float with a strobe light into the water to help mark the location of the swimmer. The good news is that almost all vessels now have GPS as part of their equipment, and you can easily "retrace your steps" with great accuracy.
Anyway, at night, as in daylight, if you
see the person fall in, yell "Man Overboard, Starboard/Port side!!", throw anything that will float (for the person to grab AND to help mark the spot) and point at the person in the water. The boat driver should instantly hit the "man overboard" button on the GPS, and if he has one at hand should drop a floating strobe light into the water.
I've participated in and conducted "big ship" man overboard drills in the days before GPS both day and night as a young Merchant Marine Officer. We used "dummies" with life jackets on them, and at night the life jacket had a strobe light or chem light (bright white strobe is better than the chem lights).
My experience is that at night, without a lighted float and GPS to help you, you will be
very lucky to find the victim if you lose visual contact with them. And on a very dark night you will lose visual contact within moments.
On a big ship you do the Williamson Turn as mentioned by DennisS, and if performed properly you end up steaming right back up your own wake to the person in the water. This makes good sense on large vessels due to their low maneuverability and long stopping distances. On anything other than a very large liveaboard however I'd say skip the Williamson, just full stop then tight 180. Most dive boats will "spin" in close to their own length, so this is what should be done. A Williamson Turn just carries you away from the victim as your perform it, and if it is not performed correctly you can be worse off than just stopping and spinning around.