You sometimes may be immersed in cold water for prolonged periods of time or shore is too far away, rescue is not imminent, no boat is available to get into or on top of, and no flotsam is available.
If you are wearing a life jacket or PFD (Personal Flotation Device) or buoyant clothing, your survival time can be increased by adopting the HELP position. This position somewhat protects the core areas of the body from rapid heat loss.
If you fall into the water without protective clothing or a survival suit, it is only a matter of time before your body temperature drops enough to render you unconscious and you become a victim of hypothermia.
You can prolong your survival time. If you’re alone, you should adopt the heat-escape-lessening posture (HELP), which involves leaning back against the collar of your life jacket and folding your arms across the front of the jacket to hug it close to your body.
You should cross your legs below the knees and draw them up toward your chest as high as you can. In this way, you will trap as much heat as possible within the immediate vicinity of your body.