Protection from the hazards of the environment should have highest priority and, as survival is likely even after some days without water and some weeks without food protection and water supply, should have a far higher priority than nutrition. In water temperatures below 15°C crew must abandon ship wearing cold water immersion suits in addition to modern inflatable lifejackets, even if they are kept initially safe in boats or life-rafts. Every effort should be made to board the life-raft dry if at all possible.
General Actions Prior to Abandoning Ship
Hazards of Immersion
Immersion after shipwreck is associated with many other hazards besides cold and drowning. Acute dangers to the individuals in the water include entanglement or traumatic contact with structures from the sinking ship, suction, inhalation and contamination with fuel oil, trauma from surfacing buoyant objects from the sinking ship and underwater explosions.
Surface fuel oil contact should be avoided as far as possible. Direct contact is not inhernetly dangerous due to its negligible systemic toxicity. However if swallowed it may cause vomiting, if inhaled it may produce pneumonia and if brought into the eyes it will produce conjunctivitis.
Burning oil at the sea’s surface is a hazard. If a person has to jump from the ship into burning oil they may be able to avoid being burned if the following procedure is adopted:
- Remove lifejacket and cumbersome clothing.
- Jump feet first through the flames.
Distress – Survival in Life-Rafts
Long term survival in life-rafts is a specific problem characterized primarily by a cold, wet environment and insufficient potable water, at lesser degree by food deficiency. Maintaining the discipline and morale of the survivors inside life-raft is of utmost importance.
Disturbances of fluid and energy balance are closely related. They may impact on performance, health, discipline, morale and survival. However, modern communications and location devices make it rather unlikely that survivors will spend the time needed to develop nutritional deficiencies in a life raft. Thus, supply and conservation of water is crucial.
Cold – Thermal Insulation
Thermal insulation in a life-raft is the highest priority. Free water inside life-raft reduces the insulation significantly. All measures must be taken from the very beginning to control of any ingression of water. Common leaking sources buoyancy tubes that are only partially inflated and which lead to waves breaking inboard at the open windward entrance.
Sitting positions on the life-raft floor contribute to conductive heat transfer. This is aggravated be any free fluids sloshing around the floor (i.e. leaking water, condensation, vomit, urine). Fluids will accumulate in the depressions of the inflated floor created by the sitting occupants. Additional blankets are beneficial. If the risk of capsize is small it is recommended that lifejackets are removed inside the life-raft and used as insulating cushioned seats instead (13).
Occupants in wet clothing should remove the outer layers, squeeze them dry, and put them back on. The manoeuvre will cost little body heat and will not affect heat balance over the long period.
Heat given off the occupants will warm up the environment within the life-raft reasonable quickly provided that good sealing of the apertures can be maintained. Warming will be reduced by wearing waterproof clothing or survival suits.
Any dry clothing, preferably wind stoppers, capes and head coverings will reduce heat loss through radiation. This will lead to a prolonged period without cold shivering. During shivering the energy demands will increase significantly. However, good sealing of life-raft is difficult to maintain over the time. Cooling through evaporation will continue and must be considered even under obviously good sealed conditions.
Protracted exposure in cold conditions combined with insufficient energy intake will diminish shivering, thus reducing intrinsic heat production by muscular activity. With starvation, shivering will be almost absent. Body core temperature will fall. If dehydration is present cold related injuries are aggravated and cooling of the body core will be enhanced.
Dehydration in excess of about 5 percent body weight may be associated with headache, irritability, and feelings of light-headedness.
With losses of 10 percent, performance declines significantly. Further losses lead to hallucinations and delirium. Death usually occurs with acute losses of 15 to 20 percent of body weight. In a marine environment this occurs in 6 to 7 days.
For the average resting adult, recommended minimum daily requirement for fluid is 1 litre. In a survival situation this may be reduced to a daily in take of 150 to 450 ml of water for a limited 5-6 days period. Survival packs in life-rafts contain water supply of half a litre for a 5 day period per person.
Water balance can be maintained best on a diet which is rich in fat and carbohydrate but low in protein.
Survivors can reduce water requirements by minimizing energy expenditure and water losses (13,14):
- No drinking at all in the first 24 hours, except the injured.
- Never drinking seawater.
- Never mixing seawater with fresh water.
- Minimizing activity.
- Resting during the heat of the day.
- Optimizing the use of shade and breeze.
The life-raft survivor should reduce fluid loss by vomiting, by taking anti-seasickness tablets as soon as possible, either before or immediately when entering the life-raft.
Alternative safe means of acquiring water should be considered early (13):
- Collection of rain is often the only source of water replenishment available to the survivor at sea.
It is a safe source; however, the initial wetting must not be collected as it will wash salt crystals from the collecting awning or canopy.
- Condensation water is a safe alternative.
- Seawater is never a safe alternative.
Deaths in life-rafts following the drinking of seawater seem to be the result of fairly rapid onset of respiratory failure, mostly preceded by mental derangement. Delirium leads to apparent insanity, aggressiveness, risk of suicidal actions and death. Usually there are no typical signs of dehydration. There is no beneficial effect in mixing fresh water with seawater. On the contrary it will lead to the same catastrophic events.
- Other safer alternatives are: Reverse-osmosis pumps and solar stills, if available; squeezed extracellular fish fluid (lymph) and spinal fluid; turtle blood.
Death from starvation takes 40 to 60 days. Food is usually not the leading problem in survival at sea. If sufficient hydrated physical and mental capabilities will be stable until bodyweight loss exceeds 10 percent. Furthermore, the absence of vitamins, minerals, or trace elements is unlikely to pose a problem to life-raft survivors at sea for less than two months.
For the average resting adult, daily energy expenditure is 1400 kilocalories. In a survival situation this daily requirement may be reduced to an intake of 600 kilocalories for a limited period. For the prevention of catabolism and dehydration the food taken should be in the form of carbohydrate. This means avoiding eating protein unless fresh water is freely available. Fat reserves are plentiful, but glucose is required to enable the metabolism of fat. Protein reserves are also reasonably plentiful and can be used to provide the glucose to enable fat metabolism, but muscle wasting and protein deficiency disorders will quickly follow. A minimal daily intake of carbohydrate will help offset this. Food packs in life-rafts are assembled accordingly (13,14).
Morale and Discipline
In a survival scenario prospects increase significantly if survivors manage to react calmly, appropriately and effectively. An assortment of physical and psychological ailments in combination with other stressors can erode morale and decrease survival at sea.
A leading person who is acting as the senior survivor in life-raft should set a good example, guide others, and contribute to a positive mental attitude until final recovery. Ship’s doctor is one of the trusted persons to take over this job.
Important rules for raising morale and discipline are:
- Never abandon hope for rescue (15).
- Keep comradeship at a high level.
- Provide every survivor with special tasks.
- Avoid brooding.
- Monitor each other for suicidal actions.
- Set a good example for others.