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EXECUTIVE SUMMARY

1. Currently within Canada’s internal lakes and rivers, there are numerous personnel being moved over water during the winter and spring months in vessels without the provision of liferafts. Whether this is an acceptable state of affairs is the question addressed in this research paper.

2. The facts about the dangers of immersion in cold water are as follows:

(a) There are four clear stages of immersion in which death can occur. These are: 

1. Cold shock (kills within 3-5 minutes after immersion).

2. Swimming failure (kills within 30 minutes after immersion).

3. Hypothermia (kills after 30 minutes of immersion).

4. Post rescue collapse (kills at the point of rescue or up to several hours afterward).

(b) The cause of death associated with each stage respectively is:

1. Drowning, heart (circulatory) and respiratory problems.
   

2. Impaired physical performance leading to inability to self-help, swimming failure and drowning.
   

3. Deep body cooling leading to hypothermia and drowning.
   

4. Collapse of arterial blood pressure leading to cardiac arrest.

3. Up until 5-8 years ago, the problems associated with stages 1-2 and 4 have largely been considered of academic interest only. Stages 1, 2 and 4 can have a profound influence on survival probability as the water temperature falls and the sea state worsens. With regard to the condition of hypothermia, for a normally clothed "typical passenger" this is accelerated if whole body exercise is performed in the water (i.e. swimming).

4. Historically, there has been a preoccupation with hypothermia. This has been reflected in the predictive survival curves based on the time to reach hypothermia. Thus, excellent teaching and training programs, standards and equipment have been developed aimed at reducing this specific threat. However, it is now considered that the early responses to immersion (stages 1 and 2) probably account for the majority of open water immersion deaths.

5. Survival prediction curves are of limited value only. This is because they do not take into account that death may occur from cold shock, swimming failure and drowning during early hypothermia. The curves should be revised to include these factors.

6. The initial responses (stage 1) peak in water between 10-15ºC. Swimming failure (stage 2) occurs much sooner in cold water than in warm water, even in proficient swimmers. As a consequence, humans tend to grossly over-estimate their swimming capability in cold water. This is a little known, but central factor in the cause of death.

7. From all the combined research on cold water accidents and scientific research, it has become clear that sudden immersion in cold water, (i.e. below 15°C) is very dangerous. It should be avoided if at all possible. Furthermore, a conscious decision to swim (and rescue oneself) or stay floating still in the water should not be taken lightly without assessing the pros and cons. It has now been shown that a person’s swimming ability in warm water bears no relationship to that in cold water.

8. These scientific findings lead to practical advice regarding the regulations requiring the carriage of liferafts and training of operators of passenger carrying vessels.

1. Wherever possible entry into water below 15°C should be avoided. Direct entry into a life raft should be the objective.
   

2. Transport Canada should use this philosophy in the design, development and implementation of all new legislation. All vessels operating in Canadian lakes and rivers at 15°C or below should carry liferafts that can be easily launched and boarded by the entire crew and passengers.
   

3. The only exception to this should be where it is physically or practically impossible to stow a liferaft. Under such conditions the passengers must wear inflatable lifejackets when on board.
   

4. Closeness to the shore or the carriage of EPIRB are not a reason for waiving this requirement because death from cold shock will occur within 3-5 minutes, and swimming failure in under 30 minutes. EPIRB responses have averages between 90 minutes and 2 hours.
   

5. The Marine Emergency Duties curriculum should be amended to include the two new Canadian videos on cold shock, swimming failure, hypothermia and post-rescue collapse.
   

6. Even though there are well established teaching programs, regulations and much improved life saving equipment, there are still in the order of 140 000 open water deaths each year. What has been overlooked is the significance of the first two stages - cold shock and swimming failure as a cause of death. The precise details of these are described in this report.

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