People who avoid drowning still face the risk of acute hypothermia as the body's core temperature decreases. If the rescued seaman is fully awake and shivering, treatment for mild to early moderate hypothermia is reliably effective and evacuation is unnecessary.

PA1 DANIELLE DEMARINOA Coast Guard crew treats a migrant who spent 29 hours at sea after her boat capsized. The woman appeared to be in shock, with signs of dehydration and hypothermia.Fluids and carbohydrates will help the person warm up through vigorous shivering (the body's way of generating internal rewarming heat). If dry, insulating clothing is not available, provide an extra windproof barrier by dressing the person in foul weather gear to minimize heat loss. When practical, wrap the person like a burrito in blankets, sleeping bag, sails or sail bag. Allow the person to shiver; external heat, such as a hot shower, is not necessary and may in fact be dangerous.

If the person has been immersed in cold water for a prolonged period, advanced hypothermia – in which the person is perilously close to losing both consciousness and the shivering reflex – can set in. More aggressive and sophisticated rewarming methods are required, and it is prudent to take the person to a medical facility for careful monitoring.

Be aware that severe hypothermia can occur even if the rescued sailor is in an apparently stable and conscious state. These people have low blood pressure, and their condition will rapidly deteriorate with any activity or attempt at external rewarming, such as walking around the rescue craft or taking a hot shower. They must be kept still, in a supine position and handled gently to avoid physically stimulating the heart to change its rhythm or stop beating.

During helicopter evacuation, use a litter with straps so the person can remain horizontal and securely bundled. The rotor blades create a wind-chill from the downwash and can increase the level of hypothermia. Dress and wrap the person properly during transfer.