Here is some information on first aid on board a vessel. At sea, the most likely causes of accidents and illnesses requiring urgent intervention are: drowning, hypothermia, sunstroke and, most common of all, seasickness.
Drowning is the condition of a person who has ingested and inhaled water. The typical intervention is artificial respiration with chest compression (at first from the drowning persons back, to allow water to flow out of the lungs) or with the mouth-to-mouth method. Whenever possible, vomiting should be induced in the afflicted person to help him/her expel ingested water, and his/her body should be kept warm because drowning is almost always associated with hypothermia.
Hypothermia can occur when a person has been in water for too long and has consequently lost body heat to the point of being almost unconscious. Classic symptoms include a state of shock, inertia of the limbs, often even loss of consciousness. What to do in this case? Firstly, wet clothing should be removed, then the person must be wrapped up warmly, keeping him/her facing upwards with head lower than the rest of the body. When other means are unavailable, a good method of warming up a person with hypothermia is to wrap him/her with ones own warm, naked body. If the person is conscious, make him/her drink warm and non-alcoholic beverages.
Sunstroke happens very frequently, especially in summer. It is an excessive absorption of heat by exposure to sunlight. This condition becomes especially dangerous if it affects the head. Sunstroke symptoms include red skin, severe headache, nape pain and often vomiting. Sometimes high body temperature and delirium are also present. Treatment is to keep the person in a cool and dark environment, placing an ice bag on his/her head, and giving cool (but not cold) drinks and pain killers.
Seasickness is due to a problem involving the equilibrium sensors: it is a subjective disease, as in fact some people fail to properly compensate the movement of the vessel they are on, resulting in the onset of dizziness which leads to nausea and specific physical and psychological consequences. Although people experience this annoying condition to a greater or lesser degree, no one is totally unaffected by it, and even old sea dogs may suffer from it. More than remedies, the key here is prevention which, in addition to specific drugs, consists of certain behavioral rules: do not stay in hot indoor environments fresh air can already be a first relief; do not eat sweets nor drink too much: bread, potatoes and crackers are the ideal foods; do not smoke, nor stand next to someone who is smoking; look at the horizon. Moreover, certain factors have a strong influence on the onset of seasickness: among these are tiredness, food and atmospheric pressure.
Concerning hypothermia, drowning and sunstroke we recommend you gather further information from specialized books or websites before you leave for your vacation.