There are two ways of improving the chances of survivor detection and location:  1. Make the person in the water more visible  2. Improve the ability of the Searchers to 'see' the person in the water.  The Sea Marshall Man Overboard Emergency Response Locator Beacons & Receivers give you both these options. In the event of any kind of Man Over Board incident it is crucial that the missing person is firstly detected as missing and then located and recovered from the water in the fastest time possible.  The Physiological Effects Of Immersion are often overlooked, in cold water hypothermia develops very quickly, the majority of those entering water without immersion suits will die within one hour.  Question So what happens when a person goes into cold water? Answer Initial Immersion, the first two or three minutes. The danger here arises from the initial "cold shock" responses to cold water immersion. Survivors will experience a sudden fall in skin temperature, decreased breath holding ability, muscle spasms and many hyperventilate. During this time it is unlikely that any person will be capable of any operation requiring a high degree of manual dexterity, such as operating a distress transponder of any type. 'The Sea Marshall Beacons automatically activate after 17 seconds continuous immersion alerting the crew that a person has gone into the water and allowing the rescue operation to commence' The following is reproduced from US Coastguard  Regulations 33 CFR 181.705 equating water temperature to survival time. WATER TEMP WATER TEMP EXHAUSTION/ UNCONSCIOUSNESS EXPECTED TIME OF SURVIVAL   32.5°F Less than 15 mins 15 to 45 mins 0.28°C to 4.4°C 32.5°F to 40°F 15 to 30 mins 30 to 90 mins 4.4°C to 10.0°C 40°F to 50°F 30 to 60 mins 1 to 3 hours 10.0°C to 15.6°C 50°F to 60°F 1 to 2 hours 1 to 6 hours 15.6°C to 21.1°C 60°F to 70°F 2 to 7 hours 2 to 40 hours 21.1°C to 26.6°C 70°F to 80°F 3 to 12 hours 3 hours to indefinite >26.6°C Over 80°F indefinite indefinite