There are many risks when stranded at sea. In both hot and cold climates, your survival depends on quick thinking.
If you are in a cold climate, put on an antiexposure suit. If this type of protection is unavailable, put on any extra clothing available. Keep clothes loose and comfortable. Take care not to snag your raft with shoes or sharp objects. Keep the repair kit where you can readily reach it.
Rig a windbreak, spray shield and canopy. This can protect you from the elements and provide extra insulation. Try to keep the floor of the raft dry. Cover it with canvas or cloth for insulation.
If you are with a group, huddle together to keep warm, moving enough to keep the blood circulating. Spread an extra tarpaulin, sail or parachute over the group. Give extra rations, if available, to survivors suffering from exposure to cold.
The greatest problem you face when submerged in cold water is death due to hypothermia. When you are immersed in cold water, hypothermia occurs rapidly due to the decreased insulating quality of wet clothing and the result of water displacing the layer of still air that normally surrounds the body. The rate of heat exchange in water is about 25 times greater than it is in air of the same temperature.
Your best protection against the effects of cold water is to get into the life raft, stay dry and insulate your body from the cold surface of the bottom of the raft. If these actions are not possible, wearing an antiexposure suit will extend your life expectancy considerably. Remember, keep your head and neck out of the water and well insulated from the cold water’s effects when the temperature is below 19 degrees C. Wearing life preservers increases the predicted survival time as body position in the water increases the chance of survival.
If you are in a hot climate, rig a sunshade or canopy. Make sure to eave enough space for ventilation. Even if it is hot out, try to cover your skin, where possible, to protect it from sunburn. Use sunburn cream, if available, on all exposed skin. Your eyelids, the back of your ears and the skin under your chin sunburn easily.
Information courtesy of the U.S. Army Survival Manual