Seasickness, also known as motion sickness, is a common problem experienced in survival craft. It is characterized by loss of appetite, nausea, dizziness, and vomiting. Preventive medicines can often help reduce or avoid these symptoms.

Sunburn is another major medical hazard faced at sea, regardless of the location. It can range from mild first-degree burns to severe third-degree burns depending on the level of exposure and protection. Initially, sunburn presents with redness, swelling, and tenderness of the skin, and may be accompanied by pain, fever, nausea, vomiting, diarrhoea, weakness, or even extreme exhaustion.

Sunburn can be prevented by keeping the body fully covered with clothing at all times and by staying under shade whenever possible. Survivors should avoid looking directly at the sun or the glare reflected from the water. Wearing sunglasses during daylight hours is important. Additionally, sunscreen should be applied generously to all exposed parts of the body to reduce the risk of burns.

Hydration and nutrition

If rescue is delayed, maintaining proper hydration and nutrition aboard a survival craft becomes increasingly difficult. In such situations, water is far more important than food. Food supplies in lifeboats are usually very limited and often consist only of items such as hard candy, which provides a small amount of energy. Its main benefit is psychological, as it helps boost the morale of survivors who are hungry.

Although survival craft carry a limited supply of drinking water, they may also be equipped with desalting kits or solar stills to produce additional water. Each desalting kit can produce about half a litre of safe drinking water. This water may taste unpleasant and appear discoloured, but it is safe to drink if prepared correctly according to the instructions. A solar still can produce approximately four litres of water per day in temperate climates with sufficient sunlight. The water produced in this way is usually clearer and more pleasant than desalinated water. Efforts should also be made to collect and store rainwater whenever possible.

If it is expected that rescue will not occur within one day, only a minimal amount of water should be given during the first 24 hours. This allows the body to activate natural water-saving mechanisms, which will reduce the need for water later. Survivors who have been in the sea for some time or who have swallowed seawater may feel extreme thirst, and this should be relieved to some extent. After the first day, each person should be given about half a litre of water per day. In hot tropical climates, this amount should be increased if supplies allow, because sweating leads to greater water loss.

Heat exposure

Exposure to tropical heat creates additional problems for survivors aboard a survival craft. In such conditions, the body may lose large amounts of fluid through sweating. Although the human body can adjust to high temperatures to some degree, complete adaptation is rarely achieved. To prevent dehydration, physical activity should be minimized during the daytime, and clothing should be used effectively to create shade, such as by forming a canopy.

Dehydration is treated by increasing the intake of water, depending on availability. Heat exhaustion occurs due to loss of both water and salt from the body. Heat cramps are another condition caused by salt loss and are characterized by painful muscle spasms in the limbs, back, or abdomen. In such cases, the skin is usually moist and cool, and muscle twitching may be observed. Heat-stroke, also known as sunstroke, is a serious medical emergency that requires immediate attention.