Throughout history, men have dived beneath the sea to gather food, explore or recover lost objects. What many do not know is for just how long men have been inventing and utilising diving equipment in the quest to go deeper and to stay underwater longer. Over 3000 years ago the Greek philosopher Aristotle recorded how ‘men went underwater in a metal vessel which was lowered to the seafloor. It did not fill with water but retained the air trapped inside it, allowing the men to breathe and to work on a sunken ship.’ He was referring to the diving bell, a spectacularly successful piece of diving equipment that has remained in use in various forms to the present time.
The original diving bell was made of wood, bound with iron straps and weighted with lead, and was able to take men down to depths of around 15 metres. It suffered one major drawback: it could only stay underwater until the air inside it became fouled with carbon dioxide. This limited salvage operations to 15 or 20 minutes, depending on the depth and the number of men breathing the air.
In 1717 Edmund Halley, who was to later give his name to famous Halley’s Comet, invented a more successful diving bell. Two and a half metres high and one and a half metres in diameter it was made of wood, weighted down with lead and open at the bottom. Halley’s bell was superior to all previous ones because, after it was lowered to the bottom of the sea, the air could be replenished by lowering weighted barrels with fresh air. Halley and four companions once remained at a depth of 18 metres for one and a half hours. This feat would have put them at risk of suffering the bends – potentially fatal nitrogen bubbles in the blood – but this danger was unknown at the time. It seems that ignorance was bliss because there are no reports of any illness or death.
Engineer John Smeaton, who later became famous for the tower he built at Plymouth, was responsible for the next major breakthrough in underwater engineering. In 1778 he was working on a bridge in Northumberland that needed repairs to its underwater foundations. He developed a force pump to continuously supply air to the divers working in a bell on the bed of the river Tyne. After this invention, many attempts were made to make a diving suit that relied on a single air hose from the surface but without success.
Eleven years later an Englishman named Klingert made the ingenious combination of a cast iron helmet fitted to a leather suit. His air supply was lowered down with him in a large steel cylinder, which considerably limited the diver’s movements.
In 1837, some 48 years later, Augustus Siebe perfected previous pioneering work and drew Klingert’s and Smeaton’s work together. He invented a copper helmet with windows and a rubberised canvas suit and lead-weighted boots.
The helmet was supplied with fresh air from the surface by a powerful pump. Today’s standard salvage-diving dress is basically the same equipment that Augustus Siebe perfected and that has been used throughout the world ever since.
In 1860 two virtually forgotten Frenchmen, Rouquarol and Denayrouze made the first self-contained diving suit. It consisted of a standard Siebe helmet but was supplied with compressed air from a cylinder on the diver’s back. The air first passed from the cylinder through an automatic pressure regulator, which could compensate for the increasing depth, rather like the modern aqualung.
The next significant invention was, as is usual, brought about by necessity. During World War II it was realised that if divers were to attack ships in harbour and blow them up they would need self-contained diving sets that did not give off bubbles. They would also need to be able to remain underwater for a considerable time. The oxygen re-breather, or closed circuit breathing set, was developed. Operation of the closed circuit was accomplished by feeding oxygen through a regulator into a rubber counter-lung from which the diver breathed. As the diver exhaled into the counter lung, the waste gas from his body (carbon dioxide) was absorbed by chemical crystals. Only the unused oxygen that he breathed out, re-entered the bag to mix with more oxygen being fed from the storage cylinder. Because all the waste gas was absorbed within the system, there were no bubbles to give away the diver’s presence.
Both Italian and British frogmen used this form of diving equipment on numerous successful attacks on each other’s ships, and it was standard gear for the human torpedo and midget submarine crews. The serious disadvantage of breathing pure oxygen is that it becomes poisonous at a depth of 10 metres, where the atmospheric pressure is double that of the surface due to the weight of the water. This diving sickness is also a problem for the helmet diver who goes to great depths using compressed air. The percentage of oxygen in the air is 21 percent, but at a depth of just over 90 metres, the partial pressure of oxygen in the air is equal to two atmospheres, meaning that a deep-diving, air-breathing diver can also suffer oxygen poisoning.Nitrogen narcosis, sometimes called ‘the rapture of the deep’ or ‘the narks’, is another danger when air is breathed under pressure. The air we breathe contains 79 percent nitrogen. When a diver goes beyond 76 metres or less for some individuals, the nitrogen has a mildly intoxicating effect. It can make the diver feel slightly drunk and begin to lose judgement and control. Once a diver has become confused like this, the only remedy is to bring him up to a lesser depth.
These dangers can be overcome by excluding nitrogen, which is an inert gas and plays no part in respiration, from the gas that the diver breaths, as well as lowering the partial pressure of oxygen, usually by adding helium. Divers can now penetrate to great depths, breathing helium with only a tiny percentage of life-supporting oxygen in the mixture. Mixture breathing is only for professional divers on oil rigs and in ocean research and deep salvage work.
For the everyday salvage diver or the well-trained amateur, the biggest danger in diving is the bends, more correctly known as Caisson’s disease or compressed air illness. The bends got its nickname from the bubbles of nitrogen that often get caught in the bends of the body – at the elbows, shoulders or knees, for example – and which can cause permanent paralysis to the joint. While the diver’s body is under compression at depth, the nitrogen present in the air changes from a gas in the lungs to a solution that passes into the bloodstream. When the diver comes to the surface the process takes place in reverse and the nitrogen is exhaled. However, if the diver ascends too quickly it is possible for the nitrogen to turn back into gas while still in the bloodstream. These bubbles then carry on along the blood vessels until they either become lodged in a joint of the body or they reach the heart or brain, with fatal results. The severity of an attack of the bends is determined by three factors: the depth a diver descends to, the amount of time spent there and the rapidity of his ascent.
In well-run organisations, such as navies and salvage companies, all divers ascend in accordance with dive tables. For example, if a diver has been working on the bottom at 55 metres for only 10 minutes, he will be brought to the surface slowly, pausing for only three minutes at three metres before reaching the surface with all the dangerous nitrogen leached from his system. If the same diver stays on the bottom for an hour, he will have to make five separate stops to complete a total decompression time of 167 minutes. It will, therefore, take him almost three hours to rise from the seabed to the deck of the diving vessel.
Recent technology allows divers to surface before decompressing. They come up almost at once, undress quickly and enter a recompression chamber where they can be subjected to the same pressure as the depth from which they have just ascended. A further development of the recompression chamber is used by oilrig divers, who go to incredible depths and remain pressurised for weeks at a time. Saturation diving, as it is known, allows divers to live in a warm and comfortable, though cramped, environment for weeks on end at the same pressure as the water in which they have to work. Once the human body has been subject to great pressure for 48 hours, it becomes so saturated with an air mixture that no further nitrogen is absorbed by the blood. Whether the diver remains at that depth for weeks or months, no further decompression is required. However, there are many physical, psychological and practical problems in putting men into inner space. In late 1991, off Malaysia, a diving vessel sank in a typhoon, carrying down with it a number of divers in their steel decompression chamber. All died lingering deaths, locked inside what became their coffin.
In recent years there has been a change in underwater technology that allows men to dive ever deeper, not in diving suits but in small submarines. Dr Robert Ballard of the Woods Hole Oceanographic Institution, USA, developed an underwater three-man submarine named Alvin, which located and penetrated the wreck of the Titanic.
When the Titanic sank and settled at a depth of over three kilometres, no one imagined that human eyes would ever see her again. But in 1985, backed by a joint American and French team, Dr Ballard located the lost liner after nearly three-quarters of a century. Alvin had a tiny unmanned submarine called Jason Junior – JJ for short – attached to her nose by a long umbilical cord. While Alvin sat on the Titanic’s deck, JJ was piloted by remote control into the interior of the vessel, videoing and photographing where no manned submarine or diver could reach.
The result was a fascinating look at maritime history, frozen forever in the oxygen-starved deep ocean of mid-Atlantic. Dr Ballard and his team went on to locate and photograph the mighty German battleship Bismark, sunk by the British, or possibly scuttled by her own crew, to prevent her being captured, during the war.
Outstanding and laudable as these underwater feats may be, perhaps the greatest advance in diving has been the invention of the common aqualung. In France, in 1943, Cousteau perfected the first practicable open-circuit breathing set by adapting a regulator from a gas stove borrowed from a friend’s caravan. Compressed air from a cylinder, worn on the diver’s back, was led through a reducer to a valve that allowed the diver to breathe. A diaphragm was incorporated, with air on one side and water on the other, allowing the pressure of the air breathed to be equal to the water pressure. When the diver breathed out, the exhaled gases were lost in the sea as bubbles. This invention, along with the development of the neoprene diving wetsuit, has allowed millions of people to enjoy the mysteries of the ocean depths. Major advances in diving medicine have allowed us to understand what the human body can tolerate underwater, which has made diving safer.
Of course, it is not just the quality of equipment that dictates a diver’s safety. Personality, pride and ego all play their part too. Because of the strength required to work in underwater salvage the trade has historically been the domain of men. For example to counter the buoyancy of the air in the suit and helmet, divers have to carry additional lead weights on their chest and back and also wear extra heavy lead-soled boots, In addition to that, on most jobs, they often have to carry special tools and always carry a divers knife.
Consequently, professional divers have acquired a rather macho image. The divers of old were considered strong, independent types who worked hard and played hard, although any rivalry between them was usually good-natured and hardly ever aggressive. But, there are exceptions to every rule and during the summer of 1842, an incident occurred that was to be the first and possibly the only recorded occasion when two rival divers began fighting underwater. During the summer that year an incident occurred at Spithead that was to be the first and possibly the only recorded occasion when two friendly, but rival divers began fighting underwater. At Spithead that summer Major General Paisley had 24 men of the Royal Sappers and Miners and ten men from the East India Company of Sappers, employed in the removal of the wreck of the King’s ship, Royal George, which was considered a hazard to navigation. Six years before this incident the now famous Augustus Siebe had perfected the standard divers dress, comprising a rubberised canvas suit, copper helmet and lead-soled boots. The helmet was supplied with air by a strong force pump which was hand operated by two men on the surface.
The men under Major General Pasley were using the Siebe helmet and suit and working at a depth of 98 feet. The Sappers working on the wreck were very keen and although there was no financial reward for bringing up more wreck than anyone else, there was a great sense of pride in being the best diver. This somewhat misplaced sense of pride led to much rivalry amongst the divers which, in time, became dangerous.
Men would push themselves to the limits of endurance and come to the surface absolutely exhausted in order to bring up just a little bit more wreckage than anyone else. They also risked getting the bends, but because no one knew what caused the bends in those far off days, ignorance it seems was bliss. The most expert and successful of the divers was a certain Lance Corporal Peter Jones, who daily risked his life to burrow deep into the mud to recover tons of pig-iron ballast weights which were considered a real treasure. Another of the top divers was Private Girvan who tried hard to beat Corporal Jones’s output of wreckage recovered from the wreck. A very unhealthy rivalry developed between the two top divers and in time their intense competition became more perilous than the diving.
One day both Corporal Jones and Private Girvan were on the wreck together and at the same moment grabbed opposite ends of the same beam. Both insisted on claiming the beam as their own and there was a certain amount of pulling and tugging until both divers came together and began to fight. It must have been the most ungainly of fights as the two heavily clad adversaries attempted to slog it out on the seabed. Punches were ineffectual as most of the vulnerable parts of each diver’s body were covered in copper, brass or lead and the resistance of the water reduced the power of every punch.
They swirled around, becoming entangled in each other’s lines and stirring up the mud. In the confusion, Private Girvan fell onto the sea floor and Corporal Jones couldn’t stop himself from aiming a kick, with his lead-soled boot, at Girvan’s helmet, cracking the face glass. Water began to squirt into the unfortunate diver’s helmet, which quickly brought both divers to their senses and made them realise what a dangerous game they were playing. Their air hoses and breast ropes were hopelessly entangled so Jones did the only thing that he could think of. He gave the signal on both breast ropes to haul both divers to the surface. Girvan was brought to the surface nearly drowned and the story of their underwater fight came out.
They were both hauled before Major General Paisley who was furious at their stupidity and berated them mercilessly. It seems that number two diver, Girvan, took most of the blame and one version of the story tells how the Major General dismissed him from the company in disgrace. However, another version of the story tells how Jones and Girvan, after realising how stupid they had been, became life-long friends and thereafter dived together and assisted each other under the water, I like to think the second version is the correct one.