Did you know you can become hypothermic in warm water as well as cold? Generally speaking, you are at risk of hypothermia if you are immersed in water long enough. Survival rates when immersed in water vary depending on water temperature, your size and physical condition, but there are water survival techniques to increase the time you can spend in the water before becoming hypothermic. These techniques become increasingly vital if you boat during cold weather or in perpetually cold waters.
Always Wear a Life Jacket
The admonition to wear a life jacket while boating can never be overstated, and is never more important than when boating in cold waters, cold weather or both. If extreme cold conditions exist, a simple life jacket will not suffice to ward off hypothermia. But, it will keep you afloat and enable you practice techniques to conserve body heat, so you should wear one whenever you boat, particularly in cold weather. To get the maximum hypothermia protection when boating in cold weather, invest in cold weather boating gear.
Get Out of the Water Quickly
Your best chance of survival lies in getting out of the water quickly. Cold water saps heat 32 times quicker than cold air, so if it is possible, get out of the water by climbing onto an overturned boat, debris or anything that will lift your body out of the water. If you are near shore, you will need to make a decision of whether to swim for safety. Distances are deceiving, and most people cannot swim a mile in freezing temperatures. Trying to do so may worsen your situation because exertion in cold water causes you to lose vital body heat.
If you are unable to get out the water, limit your movement. Band together with other survivors by facing each other to conserve body heat. If you are alone, bring your knees to your chest to conserve heat in your vital organs. When immersed in cold water, our body's natural response is to redirect circulation to our core, bypassing the extremities of our arms and legs, which increases our survival time.
Survival times vary by person and by the amount of time spent in certain water temperatures. Here is rough guideline to expected survival times by temperature of water:
70–80° F (21–27° C): 3 hours – indefinitely
60–70° F (16–21° C): 2–40 hours
50–60° F (10–16° C): 1–6 hours
40–50° F (4–10° C): 1–3 hours
32.5–40° F (0–4° C): 30–90 minutes
<32° F (<0° C): Under 15–45 minutes