On advanced marine electronics systems there is a button labeled MOB which stands for Man Overboard, specifically designed to give the exact position of someone that has fallen into the water so the Navigator can make a speedy recovery, especially in cold water conditions. Hyperthermia is a very dangerous adversary to personal survival. Required by maritime rules, commercial licensed and military mariners practice this scenario often to constantly hone the necessary skills to perform this critical operation in any weather or sea condition.
There are three different maneuvers or "turns" to accomplish that objective.
For those of you that have taken boating and license courses the "Williamson Turn" is introduced as a maneuver to return to the exact place where the person is located and retrace the path of the vessel on reciprocal course. Its chief advantage is to return to that position accurately in any condition of visibility or sea state.
In calmer waters, making a round turn or "Anderson Turn" would enable you to return to the position quickly. The advantage of this recovery method is a reduction in time to get there and is easier to perform with smaller vessels. As a boat operator you should always employ situational awareness and if this event occurs you would immediately know safe turning areas to use. Approaching from this method would also allow you to maneuver up-wind to the person in the water, which is the best and safest way to recover.
A sometimes even quicker maneuver to return to the MOB position is to execute a "Scharnow Turn" a quick turn of 240 degrees and also absolutely requires having the person in the water in sight at all times. Beware, during the turn there is sometimes the tendency to lose geographical orientation. The datum mark on the GPS chart will help guide if you are equipped but visual contact is even more important and crucial to quick, successful rescue.
These three turns are just a few examples of the process to assist in MOB. More importantly is that you have a plan and practice it enough for it to become second nature. Cold water boating brings a different set of considerations and awareness to your experience and with proper preparation and training can make for a great time underway.