- Executive Summary
- Chapter 1: The problem
- Chapter 2: How can we protect from the four physiological stages of cold water immersion
- Chapter 3: Key physical issues in the design and testing of immersion suits
- Chapter 4: Key issues in the construction of the immersion suit
- Chapter 5: Inter-relationship between the immersion suit and the lifejacket
- Chapter 6: Who needs protection and what regulations are required?
It is not possible to discuss survival in cold water and the immersion suit without considering the part played by the lifejacket. For extensive information on the design and development of the lifejacket, the reader is directed to the specific text book by this author (Reference 29). The principle of pneumatic lifejackets has been around for longer than people realize. Inflatable animal skins were used by Asur Nasir Pal’s army as early as BC 870 to cross a moat; but subsequently only crude lifejackets were available to the sailor until the mid 19th Century. As stated in Chapter 1, the principal reason for this was that sailors’ lives were considered cheap and drowning an occupational hazard and due to fate. At the Battle of Trafalgar in 1805, sailors clung to flotsam and jetsam for up to 15 hours before rescue. Impressment and wrecking did not encourage the development of lifejackets. However, the advent of iron ships around 1850 meant that ships sank more quickly; there were fewer spas and masts to cling to, and deaths at sea increased dramatically. Finally, there was some incentive to develop a lifejacket for the shipwrecked sailor.
In 1851, again as mentioned in Chapter 1, Captain John Ross Ward carried out the first human factors evaluations on a series of eight different lifejackets for the Royal National Lifeboat Institution. They chose his own design of cork lifejackets providing 25 lbs of buoyancy; this style of lifejacket was in service with the Royal Navy until the 1930s and was still used by many volunteer lifeboat crew until the end the World War ll (Figure 8). The first legal requirement to carry lifejackets on passenger carrying vessels was introduced by the US in 1852, followed by France (1884), Britain (1888) Germany (1891) and Denmark (1893). Buoyancy was provided by cork, wood shavings, balsa or rushes. Kapok was not introduced until about 1900. Macintosh had invented the technique for rubberizing fabric in the early 1820s, there were still no reliable inflatable lifejackets in service before the 20th Century.
It took a calamity the size of the RMS Titanic to force the world to produce an international lifejacket standard. This occurred in 1912 at the first IMO SOLAS convention. The standard required a buoyancy of 15 1/2 lbs , but did not specify any oronasal clearance. As already noted, no one considered investigating the physiology of drowning in cold water and applying any scientific logic to lifejacket design.
Subsequently, at many of the marine inquiries following an accident, witnesses reported that the drowned victims were generally found face down in the water wearing lifejackets. The sinking of the Vestris in 1928 was a typical example of this where 112 lives were lost. This was cause enough to reconvene the second SOLAS committee in 1929, yet the lifejacket standard was not improved.
As has been stated several times already, the Navies of the world believed in the philosophy that flotation should be provided for the castaway in the water rather than on or out of it. That led to the development of a whole series of floats and rafts (Figure 44). Very few men were supported out of the water, the majority were required to hang on to becketted lines around the rafts up to their necks in frigid water. Believe it or not, when the Royal Navy went to war in 1939, the sailors were not issued with any personal flotation devices. It was only the personal intervention of Admiral Woodhouse that caused the Admiralty to re-issue an outdated Admiralty pattern No. 14124 inflatable rubber belt which provided 9 1/2 lbs of buoyancy. This had already been rejected half way through the First World War as unsatisfactory! Yet this was to be used by the RN throughout the war and for some of the war by the Canadian and New Zealand Navies.
Figure 44: The Carley Float
During the Battle of Britain, the Air Sea Rescue Service noted many drowned airmen face down in the North Sea; yet they were wearing their supposedly superior inflatable Mae West – why was this happening? This precipitated the pioneering work by MacIntosh and Pask to examine the behaviour of an unconscious human in the water (Reference 107). Wearing different lifejackets, Pask was anaesthetized many times and placed in the pool at Farnborough to evaluate flotation angle, free board and ability to self-right. Their findings laid the foundation for the modern lifejacket. In Germany following the sinking of the Bismarck investigators noted that the sailors were found face down, drowned wearing lifejackets. They instigated an extensive research program and to this day demand substantial head support to keep the oronasal cavity clear of the water.
Post war, all of these losses and equipment failures were reported in the Talbot Report (Reference 147) and McCance’s et al study for the Medical Research Council (Reference 108). This has already been explained in Chapter 1. However, what is not known is that a parallel R&D project was started to replace the RN inflatable life belt. This was led by Lt. Cdr. George Nicholl, who flew during the war in the Fleet Air Arm and was the technical advisor to the Royal Naval Life Saving Committee. He was ably assisted by E.C.B. Lee, who had been a naval officer and had seen war service too. Between them, they recorded many testimonies from witnesses who had observed humans drown and humans who had been saved from drowning. This work was produced in a series of reports which sadly appear to have been lost, but fortunately Nicholl did publish the majority of his findings in the first survival-at-sea book in 1960 to coincide with the 1960 SOLAS convention (Reference 123).
Lee continued with his work to improve lifejackets and produced a paper in Rome in 1965 on the observed performance of humans who had drowned or near drowned during the Second World War. This section of his paper is quoted in full because the findings are based on thousands of real events in the open ocean and cannot be replicated by academic investigators (Reference 97).
Experiments by Borelli and Altier, reported by Paoli Moccia in 1794, showed that most men have a density less than unity. Mackintosh and Pask showed that an unconscious man, breathing lightly, sinks in fresh water. Tests on Service personnel in Great Britain indicate that about 10% are negatively buoyant in fresh water and about 2% in salt water. A clothed man, carrying military equipment, unassisted by a lifejacket, can keep afloat for 5 minutes by his own efforts. Tests in the USA show that the following pulls are required to sink adult persons:
male 6 lbs . (2.7 kg )
female 8 lbs . (3.6 kg )
The buoyancy of the naked man depends on physique, lung capacity and the extent to which the lungs are filled with air. In general, for immersion in calm sea water without making any swimming movement: A man of average build will float upright with his mouth and nostrils just clear of the water when his lungs contain the amount of air breathed in at a normal inspiration. A man of specifically heavy build, e.g. a fat man, will float with his mouth and nostrils clear of the water even when he has emptied his lungs by a deep expiration. A man of specifically light build, e.g. a thin man, will just remain afloat with his mouth and nostrils clear of the water if he inflates his lungs as far as he can by taking a deep breath. Designing for the worst case, the specifically heavy man, a buoyancy aid equivalent to the vital capacity of the lungs, about 4.5 litres, is required to keep the mouth and nostrils out of water. A further 1.7 litres is required to bring the rest of the head and neck out of water in order to provide a safety margin, thus making a total of 6.2 litres. For the survivor at sea additional buoyancy is required to take account of the following:
weight of waterlogged clothing and footwear
possible weight of water in the lungs (a drowned man weighs 9 lbs . (4 kg ) in water)
some of the lifejacket is usually above the water and does not contribute to buoyancy
The body extremities are denser than the trunk and the spine allows bending forwards much more easily than backwards. An unconscious man in still water therefore tends to float with his face downwards, his head slightly flexed with the chin on the chest (a natural defence in man’s normal environment, facilitating breathing); the heavy arms and legs are free to flex at the shoulders and hips and in consequence hang vertically; heavy footwear, such as sea boots, emphasize the effect and urine in the bladder and the heavy pelvic structure also tend to put the legs down; air in the lungs, stomach and upper part of the intestines provides buoyancy and the body therefore floats with the upper/middle part of the trunk uppermost. The unconscious, unaided by a lifejacket, who floats face downwards, will drown. The posture of the unconscious female depends on body-build. Some women have the flotation characteristics as men; others, with large breasts and thick layers of fat on the belly wall and thighs, may float face upwards and a water logged skirt hanging downwards will tend to stabilize them in this position. Any buoyancy aid attached to the body will affect posture and should be of sufficient amount and suitably positioned to ensure that the mouth and nostrils clear the water. A vertical posture offers less resistance to vertical oscillations and places the survivor at greatest risk from periodic immersion of his mouth and nostrils. The risk of injury from underwater explosions is also greatest. A supine horizontal position places the body at minimum risk from underwater explosion but at maximum risk of death from choking. A deeply unconscious man floating on his back might die from suffocation due to his tongue falling back. A prone horizontal positions obviates death from choking but the large amount of buoyancy required to keep the mouth and nostrils sufficiently clear of the water would render the lifejacket too bulky for wear. A posture intermediate between the vertical and supine horizontal position is indicated.
The buoyancy of the lifejacket should be so distributed as to render the man unstable in the prone position and stable in the supine position. That is, treating the man and his lifejacket as a single floating body, the metacentre should be below the center of gravity when in the prone position and above the center of gravity when in the supine position. The center of gravity of a man of average stature is at a position slightly more than 50% of his height above the soles of his feet (standing) and is constant regardless of age. The center of gravity tends to be lower with shorter statures and higher with longer statures. Maximum turning moment to put an immersed man on his back and keep him in this position is obtained by making the distance between the center of buoyancy of lifejacket and the center of gravity of the man as great as possible. This is achieved by so shaping the lifejacket and securing it to the body that its center of buoyancy is as far as possible in front of the chest and as high as possible. Buoyancy is required to support the back of the neck and to prevent the head from drooping to such an extent as to put the breathing orifices under water. This buoyancy reduces the righting moment of the lifejacket and should therefore be of the minimum dimensions to support the head. The buoyancy necessary for automatically righting an unconscious survivor from the prone position is more than that required for safe flotation in the supine position. The part remaining in the water in the supine position should therefore be adequate for flotation and stability.
Effect of waves
Waves impart a vertical motion to man in the water and under some circumstances the motion may become out of phase with the wave motion with the possibility of the man sinking below the wave profile. The lifejacket should have sufficient reserve of buoyancy and the posture of the survivor should be such as to resist the vertical motion relative to the water surface. The emerged part of the lifejacket should be so shaped as to provide a breakwater to keep spray clear of the face. Survivors prefer to face the oncoming wave, they can then prepare for it and time their breathing to produce maximum personal buoyancy. With the back to the wave there is the possibility of the wave breaking over the head and wetting the face. A well-designed lifejacket will keep the survivor in a position facing the oncoming waves. Wind will also stabilize the survivor in the position where he faces the wind – wind and waves are usually in the same direction.
Effect of broken water
The air in broken water, surf and foam does not contribute to buoyancy; the survivor will therefore sink lower in the water.
Effect of jumping
It is sometimes necessary to jump into the water from a considerable height when abandoning ship. The lifejacket should therefore impart no injury to the wearer, neither should it itself be damaged, on impact with the water. It is usual to jump feet first, with the legs close together and slightly flexed at the knee, mouth closed, one arm across the lifejacket holding it close to the body and the thumb and forefinger of the other hand closing the nostrils after taking a deep breath and before impact with the water. This obviates danger to the head when striking debris in the water, in injury from the lifejacket and shock from cold water forced up the nostrils.
Progress in the Last 40 Years with Regulations and Standardization
Once Pask was allowed to declassify his data (Reference 107), he was able to work on the improvement of the lifejacket standards. This resulted in the self-righting requirement in the 1960 IMO SOLAS standard. This was followed in 1963 by the British Standard Institution BS3595 standard. For the first time this allowed approval for an inflatable lifejacket. The original requirement was for 30 lbs of buoyancy, this was subsequently increased to 35 lbs . Then in 1973, the US Coast Guard introduced their Personal Flotation Devices regulations for Type 1 through 5 lifejackets and subsequently the Underwriters Laboratories UL standards Type 1123, 1191 and 1517. The first standard that specified 120 mm of freeboard was introduced by the IMO at the 1983 SOLAS convention. After this, a whole series of standards were introduced by Germany ( DIN 7928 and DIN 7929), Canada ( CGSB 65-7-M88 and 65-GP-14), UK Civil Aviation Authority, US Federal Aviation Administration (TSO-C-13) and finally the CEN (50N, 70N, 75N, 100N, 150N, 275N standard in 1994).
What has Been the Effect of These Standards?
Providing the introduction of the standards has gone hand in hand with a good education program, the effect on improvement in drowning statistics has been quite significant worldwide in wealthy countries. In Canada, the Red Cross report published in 2000 (Barss, 2002) (Reference 17) showed that between 1991 – 1995, the death rate from drowning was steady at 1.8 deaths per 100,000 Canadians. Between 1996-2000, the rate decreased steadily to 1.2, an improvement of 33%. This represents a saving of over 100 lives each year. However, there was no improvement seen for foreign tourists with 129 victims of water related deaths in 1991 – 1995 and the same number between 1996 and 2000. This may be attributable to the lack of an education program for these people. Boating was the leading cause of drowning and males were at the greatest risk. During 1991-1995 only 12% of recreational boaters who drowned wore a PFD and between 1996 – 2000 the figure was 11%!
The World Health Database also shows this trend in drowning statistics, except in low and middle income countries. The overall drowning rate was 7.4 per 100,000 population which equates to the loss of 449,000 people drowned each year and 1.3 million people were injured as a result of near drowning. Males are at the highest risk followed by children under five years old. But in Africa the current rate is 13.1 per 100,000 population (Peden, 2002) (Reference 130). This pattern is common throughout the world. In the Netherlands (Reference 169), over the 20 year period 1980 – 2000, there was a total of 8100 drowning deaths, but the death rate decreased from 3.5 per 100,000 population in 1980 to 1.9 in 2000, and as observed in the Canadian statistics, the majority are male. In 1971, the US drowning fatalities were 20 per 100,000 registered boats. As a result of the introduction of the PFD regulations and good education programs, by 1990 the rate had been reduced to 2.9 per 100,000 registered boats. Brazil has also noted a significant decrease in drowning statistics as a result of an intense education program. There were 7210 deaths from drowning (5.2/100,000 population) in 1979 and this had been reduced in 1998 by 18% (Szpilman et al., 2002) (Reference 146).
But this must not lead to complacency, for instance, drowning is the fourth most common "accidental" cause of death in Australia and the sixth most common in New South Wales. Just over 300 people drown each year on average in Australia; a third of these occur in New South Wales. Since 1992, their statistics have fluctuated with a low point in 1996 with a drowning rate of 1.3 per 100,000 population. Currently the rate is 1.8 per 100,000 population. National figures for 1999 – 2000 reveal a significant increase in lake, river and dam drownings. The hypothesis is that the flat, still appearance of the water gives a false impression of security and yet these conditions are the most dangerous when it comes to drowning (Reference124).
What is the Current Situation?
The evidence shown above suggests that several factors have improved drowning statistics over the last 10 years. These include the combination of understanding the physiology of cold water immersion and drowning; the improvement in the design of a variety of flotation devices; extensive national and international regulations backed up by widely published education programs on drowning prevention and the option of a lifejacket or PFD for everyone whether s/he be a professional sailor, a river pilot, a recreational boater, an aircrew member flying a helicopter over water or a child using a kayak.
We have achieved more in the last fifty years than has been achieved since humans took to water in Biblical times. The recent Congress on Drowning held in June 2002 discussed the progress made in lifejacket development and the direction that should be taken in the 21st Century. At the meeting were experts from North America, Europe, South America, Japan, China, Australia and New Zealand. The following paragraphs are written specifically to address what the expert meeting recommended.
Results of the Expert Meeting on Lifejacket Technology (Amsterdam, June 2002)
(a) Nomenclature – lifejacket or PFD ?
What should the flotation device be called? There was a heated debate about this topic. Generally, the device may be called a lifejacket, a lifepreserver, a personal flotation device ( PFD ) a flotation aid or a buoyancy aid. The problem is that each definition means a different performance specification to different people. Generally speaking, the majority of the public believe a lifejacket or lifepreserver is for protection in offshore open ocean conditions with all the features of high buoyancy and self righting properties. Where there is confusion in the definition is in the terms Personal Flotation Device, Flotation Aid and Buoyancy Aid. The majority of attendees believed that these terms related to a lower performing device than the lifejacket or lifepreserver (less buoyancy and no self-righting properties). These are thought to be for use in inshore conditions and generally for recreational sports rather than for professional use (river pilots, aircrew, etc.). This is where there is a paradox because the Type 1 PFD approved by the US is for offshore operations. Thus if the nomenclature is not defined specifically, it is possible to mislead the public into purchasing a device which is inadequate for the profession or sport in which it is to be worn.
Originally, this author was of the opinion that all devices should be called lifejackets and the difference between each type should be identified by the label which identified the buoyancy and the ability to self right or not. After all, the requirement is exactly the same, no matter what the condition, occupation or sport – to keep the oronasal cavity out of water and prevent drowning. However, after chairing the lifejacket expert meeting in Amsterdam, it is clear that in the world opinion, two specific groups of flotation devices are delineated and this is the approach that Canada should take. First, there are those professionals who work in open water that require a high buoyancy device with self righting capabilities (more on this later) and this should be called a lifejacket. The second group are basically the recreational sporting community. They may need equally as much performance out of the device, i.e. the offshore yachtsperson, but generally the performance of their lifejacket is dictated by the sport that is being undertaken, i.e. passengers on a pontoon boat, individuals sail boarding or kayaking. It is assumed that these people will be conscious when they fall into the water and therefore the need for self righting is not as essential and a reduction in total buoyancy can be accepted. This device should be called a PFD , not a buoyancy aid or a flotation aid. From the discussion, it became apparent there is an additional professional subgroup of people requiring this type of PFD who normally carry out their lifesaving duties on land. Therefore, it must be possible to integrate it with their equipment. These are the police, the firefighters and rescuers involved in flood rescue. So, in the standardization process, there must be the possibility for these professionals to procure a device that can be used with all their other equipment.
If there is to be a subdivision of flotation devices into 2 types (lifejackets and PFD s), then the standards must interrelate because there is so much commonality and neither is completely exclusive. The revised standards must be modified to conform with the new ISO / CEN / IMO standards. Furthermore, Canadian representation from both groups at international meetings such as IMO , CEN , and ISO is required.
(b) Mandatory Wearing of Lifejackets
A regulation that requires passengers and operators of small vessels to carry lifejackets in the boat, but not wear them is ineffective, and does not prevent drowning. As has clearly been demonstrated in Chapter 1, as the victim is suddenly immersed in cold water, the cold shock causes a huge inspiratory gasp and s/he starts to hyperventilate while struggling to keep the oronasal cavity out of the water to prevent drowning. At this time, it is quite impossible to don any form of flotation device. As Lee pointed out, a clothed person without any equipment can stay afloat for about 5 minutes and then will drown. It must be worn before water entry. Many European nations now demand that PFD s be worn in all small vessels and enforce these regulations. At present, it is not possible to find the relationship between improvement in drowning statistics and mandatory wearing of a flotation device. A study by the Canadian Life Saving Society is about to commence to examine the feasibility of legislating the wearing of PFD s in small vessels.
(c) Wearer Acceptance and Requirement for a Continuous Updated Education Program
Going hand in hand with the requirement for enforcing the regulations is to listen to the customer and observe the change in sporting fashions. A good example of this is the introduction of the bicycle helmet which the majority of the general population complied with voluntarily before legislation was introduced about three years ago. The reason being that the helmet looks good and appeals to the macho image of the people most at risk, i.e. the 12- 30 year old male.
We have only recently got over the hurdle of not requiring a PFD to be international orange or bright yellow, and only slowly are the manufacturers constructing better fitting and better looking PFD s. The committee was unanimous in their opinion that fashion goes hand in hand with positive or negative wearer acceptance. Simply put, a lifejacket will be worn if made out of fashionable colours and styles, but not if it is made from a boring orange or yellow fabric. Starting in kindergarten with a good continuously updated education program on cold shock and swimming failure where the PFD is most urgently needed and phased in legislation, will it be possible to reduce the drowning statistics even more dramatically. It is also most important to accelerate the introduction of more inflatable lifejackets to provide user confidence and reduce the individual cost.
(d) Self Righting
The fundamental problem is that at present, there is no good, reliable national or international standard self-righting test for lifejackets. The current test of swimming on the front in the water for three strokes and then allowing the body to relax is not in itself a bad test. It does test for good sea keeping properties of the immersion suit lifejacket providing the test subject is deliberately rotated when in the water to test out the self-righting properties. Generally speaking however, test subjects cannot truly relax in the water to represent an unconscious person. Even if they have been taught biofeedback techniques to relax, it is difficult to achieve international conformity. The test also does not account for those people who fall off the side of a ship at all different attitudes into the water, and this cannot be simulated. It has been noted on many occasions that lifejackets that have been SOLAS approved will not self-right humans wearing insulated immersion suits (Hermann, 1988) (Reference 76) and (Armstrong et al., 1994) (Reference 11).
The principal reason for this is that there are practical problems here at a standards level. Assume that lifejacket manufacturer A and lifejacket manufacturer B work independently. Suit B is submitted for testing with lifejacket A in a combined test, which they pass. Unknown to B, A makes a small design change that does not affect approval of lifejacket A alone, but now the combination of A and B fails. Who is responsible? How should this be regulated? The answer is a new integrated immersion suit system standard. This would then solve the problem of yet one more layer of clothing (i.e. the lifejacket) that hinders vision, hearing and swimming capability and in many cases, when used with the 275 Newton lifejacket, the lifejacket must be partially deflated in order to climb into a liferaft
There is the requirement to find a good, realistic self-righting test. This can only be achieved using manikin technology. The first effort was made after the Rye Harbour lifeboat disaster in 1928 (Reference 100). Nothing further occurred until the Macintosh and Pask experiments (Reference 107) in World War ll. Following these, Pask purchased a crash test manikin from the Sierra Engineering Co. (Sierra Sam) to evaluate flotation angles and self-righting properties. Sierra Sam is still operated very successfully by Hermann at the Institute of Occupational Medicine in Hamburg. The RGIT in Aberdeen, in cooperation with the RAF Institute of Medicine took this concept one stage further and produced an adult manikin called RAMM. His floating position has been validated against that of humans and is currently the only reliable robust manikin that can be tossed over the side into the sea wearing various clothing and lifejacket combinations. RGIT have now developed a toddler and a baby manikin too. The newer SWIM manikin developed jointly by the US Coast Guard and Transport Canada is not, as yet, reliable and certainly not robust. The next step is to take the SWIM and RAMM technology and develop the two together one stage further. Then a standard self-righting test can be developed. An alternative and dual approach that would be advisable is to improve the fidelity of the US Coast Guard reference vest.
During the Amsterdam meeting, a group from IMO / ISO / CEN carried out a practical trial in Rotterdam. The majority of approved lifejackets were shown not to self right a human while wearing an immersion suit. This precipitated a large discussion on the requirement for self-righting or not. It is important to take a step backwards to enquire why the requirement was initially introduced into the 1960 IMO SOLAS regulations. Throughout this report, the reader will have gathered that during the first fifteen years of research post-war on the physiology of cold water immersion, the focus was on drowning from hypothermia. The logic being that as the human became semi- and then unconscious if turned face down by a wave, the lifejacket would self-right the victim. However, in any sea conditions, even wearing the most efficient lifejacket, crotch strap and face shield, it is very debatable whether the unconscious person would survive drowning or not before rescue.
This requirement for self righting has been strengthened by the pundits who suggested it is necessary in case a person is knocked unconscious as s/he inadvertently fell over the side of a vessel. However, although this must happen, being knocked overboard is not a very rare event, but being knocked overboard unconscious is a very rare event indeed. In the majority of the 140,000 open water deaths each year, the people are conscious when suddenly immersed in cold water.
The mechanism for self righting depends on an asymmetric lever action. It can be achieved with very little buoyancy if (a) the fit of the suit is good and the lifejacket is tight so that the human and lifejacket act as one unit, (b) the placement of the buoyancy is accurate, and (c) a crotch strap is worn. However, to achieve this as was clearly demonstrated in Rotterdam where the suits generally did not fit snuggly and where the customer has the option of many different lifejackets and immersion suits not designed, integrated, tested and approved as an integrated unit (see Chapter 6), then the buoyancy in the suit which provides the thermal protection may be counter productive in producing self-righting.
An additional problem in this complex situation is the case of the rapidly sinking inverted helicopter. Here, the crew and passengers wear an approved immersion suit and an approved lifejacket, yet in combination the lifejacket may not self right the victim when on the surface. But, if the victim is not conscious during the ditching, it is most unlikely that s/he would ever escape from the fuselage in the first instance. If one then assumes s/he is conscious when arriving at the surface, then the requirement for self righting is not as important.
Back in 1767, the Royal Society of Art offered a pneumatic lifejacket to the Admiralty for 27 shillings and an inherently buoyant one for 5 shillings (Reference 29). It will be no surprise to the reader that their Lordships chose the cheaper one. History repeats itself and as one ship owner stated quite clearly at the conference, as long as the device has an approved certificate, we will always buy the cheapest one. So, there is a trade off between wearer acceptance, cost and performance. You get what you pay for. The best value for money to save lives is to provide flotation first to get the person to the surface as quickly as possible to counteract the cold shock, then the second priority is to get the oronasal cavity clear of the water to aid the person to await rescue or swim to a safe refuge.
This author does not advocate the elimination of the self righting requirement, but recommends that it is only applied to very specific, sophisticated types of lifejackets, i.e. for fighter pilots lifejackets where on low level high speed ejection, the pilot might find him/herself parachuted violently into the water at an abnormal angle. At a later date as technology advances and becomes cost effective to implement into lifejacket technology, then it may be possible to add the requirement specifically to other devices for offshore lifejackets and ultimately for integrated immersion suit systems.
Removing the self righting requirement and replacing it with a performance standard that requires good lift of the oro-nasal cavity out of water and a statement that the device should produce an unstable condition in the prone position and a stable position in the supine position is a much more practical way to save lives.
(e) Face Shields & Crotch Straps
Anyone who has spent any time in open water with any wave splash and wind understands the huge improvement in performance with the addition of a face shield and crotch strap, yet few manufacturers offer these options and even fewer people connect up the crotch strap if fitted. This is yet another education problem and the next series of programs should demonstrate the benefit of such additions. All who attended the expert meeting were in favour of strongly promoting face shields and crotch straps.
Summary of Chapter 5
This chapter discusses the effects of the rapid progress of development of lifejackets since 1945 and the review of the current technical issues discussed at the conference on drowning in Amsterdam in June 2002.
- By 2000, there were national and international standards in place for lifejackets and personal flotation devices. The effect has been to reduce the overall world drowning statistics to 7.4 per 100,000 population. In the more wealthy countries the improvement has been more impressive. Canada has now a rate of 1.2 per 100,00 population and the Netherlands have a rate of 1.9 per 100,000 population. Common among all countries is the fact that males between 15 and 35 are most at risk and only about 10% of drowning victims were wearing any flotation device.
- There are several issues that need resolution:
- the nomenclature of flotation devices, lifejackets versus PFD , etc.
- the issue of the requirement to self right or not
- the development of a reliable self righting test
- whether the requirement for self righting is necessary when wearing an immersion suit
- the requirement or not to regulate the mandatory wearing of lifejackets on small vessels
- education of the improvement of performance with the use of crotch straps and face shields
- the importance of wearability and how much fashion plays in user compliance
- In the design of any flotation device, the most important criteria are:
- to return the victim back to the surface as quickly as possible to protect from drowning from cold shock,
- to provide good oronasal clearance to prevent drowning during the subsequent period following the cold shock stage and
- require it to produce an unstable position in the prone position and a stable position in the supine position to protect from drowning during the development of hypothermia.
- Flotation devices should be categorized as either lifejackets for open water operations and Personal Flotation Devices for recreational and domestic use. Current standards should be modified to recognize these two groups that will share many of the same features and be in line with the new merged ISO and CEN standards.
- If the decision is made to develop new standards for lifejackets (inshore and offshore) and PFD s (generally domestic and recreational) then because there is so much commonality between them, neither must be developed in isolation of each other. Furthermore, it is essential that preferably the committee chairman or senior representative for both standards should both attend each other’s meetings and also international meetings with IMO / ISO / CEN . If this does not happen an incongruous situation may occur where common essential parameters may not be in agreement.