When heading out on the water, avoid hypothermia by dressing warmly and staying dry. Put on rain gear before it rains, and wear wool, which traps body heat even when wet.
Also, know how wind affects cold weather. It may be 40 degrees and sunny, but a 10-mph wind could make it feel like 28 degrees.
Cold water survival also depends on other factors, including the victim’s body size, fat and activity level. Large or obese people cool more slowly than small or thin people, and children cool faster than adults.
Remember that water conducts heat much faster than air. Getting into or onto a boat or anything else that floats and moving as far out of the water as possible can save your life. Most boats will float even when capsized or swamped.
If you must remain in the water, keep your head—where about half your body heat escapes—above water. (Other areas of high heat loss are the neck, sides and groin.) Avoid the drownproofing technique, which requires putting your head in the water, as you’ll cool about 80 percent faster than if you kept your head dry.
Swimming or treading water cools you about 35 percent faster. So remain still, and if possible, assume the fetal or heat escape lessening posture (H.E.L.P.) to increase your survival time. Several people in the water can huddle close in a circle to help preserve body heat. Placing children in the middle of the circle will extend their survival time.
By keeping still, an average person wearing light clothing and a PFD may survive 2½ to 3 hours in 50-degree water. This survival time can be increased considerably by getting the body as far out of the water as possible and covering the head.
The following table shows predicted survival times for an average person in