In addition to xpda's answer : Any time you're out sailing and hat or something falls in the water, it's time to practice a MOB drill.
Run the full protocol, including yelling out "MAN OVERBOARD"
(even it's
it's a female hat).
Set up deliberate drills by throwing a fender overboard.
Practice in a variety of conditions (especially wind strength) and various points of sail.
If you use a motor and you're unskilled, you could hit the MOB with the boat or prop.
Don't do that!
You can rescue a MOB under sail, and it's a good way to improve your sailing skills.
There are many approaches, and sailors like to argue which is best.
Maybe you tack, maybe you jibe.
Approach from below the MOB, so you can point in to the wind and come to a stop just at the MOB (much like docking under sail).
This gives you time to try multiple attempts to get the MOB out if necessary, whereas a downwind approach lets you have one try at it.
To get to the downwind side, usually use a figure 8 pattern - this makes it easier to keep eyes on the MOB.
To pull someone out of the water when they're wearing a PFD: Grab by the shoulders of the PFD Push down
They will pop up; use the momentum to help pull them in to the boat.
Know which part of your boat will be easiest to pull someone in by.
On a small tender boat, that may be over the transom.
If your topsides are high, you may need to use a rope.
Tie a large bowline to go around the MOB's chest.
outdoors.stackexchange.com/users/23/Jay Bazuzi
If there is another person person onboard, have them do nothing but watch the person in the water.
They should point a finger at person in the water and never take their eyes off.
Toss out life buoys, life slings, floating cushions, etc.
If you have it, hit a man overboard button on your GPS.
If not, make a waypoint.
Stop the boat, lower the sails.
Motor back to the person in the water.
If possible, drag a rope with a float (life jacket, life sling, etc.)
on the end to the person can grab it.
If that's not possible, throw the rope or get close and try to get the person to swim to the boat.
If at all possible, do NOT get into the water.
Only if the person is incapacitated or incapable of holding into a rope
should you consider it.
Think about doing this at night.
If the boat is beyond swimming distance of shore, be sure everybody on the boat has a life jacket (and hopefully a harness) with a strobe whenever they are on deck at night.
It's pretty difficult to climb onto some boats from the water.
You should find out the best way to do this in your boat.
Losing someone overboard is probably the most dangerous thing in offshore sailing, and it is almost completely preventable.
outdoors.stackexchange.com/users/61/xpda
Addition to the other answers: when a man is overboard, one man must always point at him with the finger, so not to lose sight.
Throw something visible as soon as possible, such as a floating flag.
when you approach the victim, keep the man downwind.
The natural inclination of the boat under wind will push the downwind side closer to the water, making it easier to haul the man up.
Extremely Important
a man overboard may feel ok, but within two or three hours water produced by the body in response to seawater inhalation may start forming in the lungs, basically drowning him/her from the inside with a delay.
Treat a MOB always as a full medical emergency, and organize for a trip to the hospital regardless and as soon as possible.
Better safe than sorry.
outdoors.stackexchange.com/users/72/Stefano Borini
To actually load a person onto a boat, try a parbuckle .
This may be a rope run from a forward cleat over the side of the boat into the water with the aft end secured and wrapped around a winch.
The over board party may sit, stand or drape themselves over the rope which is then pulled taught by the winching in of the line over the side of the boat.
When the line is tight fore to aft, it should assist in the crew or the swimmer in recovery.
outdoors.stackexchange.com/users/1937/mel
Quick stop method.
MOB QuickStop (YouTube) Watching this video will not enable you to do this when you actually have an MOB.
Like any other aspect of boat handling, it must be practiced continuously.
As compared to any other aspect of boat handling, it's as critical as tying a knot or turning on your motor.
The odds are small but the consequences are steep.
Again - there is no substitute for practice (use a cushion, not a person though ;)
outdoors.stackexchange.com/users/6440/Billseagull
If someone falls overboard from a sailboat, it is firstly imperative not to lose sight of the person since finding a man in water, especially when there's waves, can be very difficult.   What techniques are there to direct the sailboat to rescue the man?
When sailing, how do I rescue a man overboard?
outdoors.stackexchange.com
<safety><sailing>
outdoors.stackexchange.com/questions/438
outdoors.stackexchange.com/users/39/Reverend Gonzo
Throw something visible as soon as possible, such as a floating flag. If you have it, hit a man overboard button on your GPS. If someone else is available, have them keep watch for and point at the man overboard.  This should be treated as a medical emergency. Try a parbuckle to load the man overboard onto the boat. This is a medical emergency. One person should keep eyes on the MOB, floating flags and the MOB GPS button can help. Parbuckles can be used to load someone onto a boat.
Floating flags and hitting the overboard button on your GPS help. Have one person watching the MOB if possible. Treat this as a medical emergency. You can load someone onto a boat with a parbuckle.