A somewhat surprising fact about boating is that hypothermia is usually a bigger threat than drowning, particularly in chilly waters. Most people are aware of the possibility of drowning, but neglect the risk of hypothermia and therefore aren’t adequately prepared to react to cold water immersion.

What is hypothermia?

Hypothermia is the condition that occurs when the body losses too much heat and begins to shut down. First, motor control of the limbs is lost, and eventually the rest of the body shuts down. The victim loses the ability to speak, has difficulty breathing, loses consciousness, and eventually dies.

Hypothermia can occur in dry cold weather, but it happens much more quickly in wet conditions due to thermal conductivity of water being much higher than air. What makes hypothermia even more dangerous to boaters is that the process can continue even after a victim has been removed from the water, and therefore would seem to be safe.

Hypothermia Prevention

Cold water immersion can cause death surprisingly quickly. Lethal exposure times for several water temperatures are shown in Figure 40. Note how the lethal exposure time decreases dramatically as you expend energy either treading water or swimming.

Hypothermia Lethal Exposure Times

The takeaway is this: if you do fall in the water, the best course of action is to conserve energy by staying in place and balling up to try to keep warm, rather than making a hopeless attempt to swim for it. Obviously, you’re also much better off if you’ve got a PFD.

Note also that these are average times for all different types of people. Those who are very old, very young, or in generally poor health will fare even worse. Use of alcohol or other depressant drugs also increases susceptibility to hypothermia.

Hypothermia Treatment

Suffice it to say that once any sign of hypothermia is observed, treatment should be sought immediately, and the victim’s health should be monitored closely. The initial sign of hypothermia, rather than just “being cold” is the body beginning to “give in.” For example, shivering stops and you don’t really feel cold anymore, just tired and weak.

To treat a hypothermia victim – or a potential hypothermia victim, i.e. any MOB – dry off the victim, get him out of wind, and get him into dry, warm clothing. Warm food or drink can also help raise the body’s core temperature. Radio for medical help immediately, and contact the Coast Guard if you believe the situation is life threatening (we’ll discuss different types of distress calls later).

When considering whether or not to call for help, it’s better to be safe than sorry. As mentioned earlier, the process of hypothermia, once set in motion, can continue even after you think you’re out of woods. It’s best to seek medical attention as early as possible.