by Jay Garnet
From him, Mike learnt at first hand, and in double-quick time, all about the problems that confront man in his attempts to work beneath the surface of the sea.
At sea level the pressure of air is a whisker over 14lb per square inch, 2000lb per square foot, something over ten tons in all on the body’s thirteen square feet of skin. Only the fact that the pressure is equal outside and inside allows us to be unaware of the weight of air. But in an environment in which the pressure outside is much less (for example, the top of a mountain) or greater (under water) we become painfully aware of the difference. Water weighs a lot more than air, and the deeper you go the more it weighs. For each additional thirty-three feet the diver descends, another atmosphere – 14lb per square inch – is added to the weight of water. When a sperm whale dives a mile below the surface, water exerts more than a ton of pressure on each square inch of its body.
But because living tissue is largely water, and because water itself is incompressible, there is hardly any sensation of pressure on most of the body; only the air spaces – the lungs, the throat, the ears, the nose – register the change. As any trainee diver is told, if you lower a grape to a hundred feet, it will return to the surface unblemished. But if you lower a sealed tobacco tin to the same depth, it will be crushed flat. The air inside is squeezed into a minute percentage of its former space, and the structure of the seemingly solid tin is no match for the weight of water around it. The diver’s problem, then, is to ensure that the pressure of air in his lungs equals the varying pressure of the water around him.
In shallow water the principles of diving are obvious enough, and divers have breathed with the help of a variety of diving-bells and helmets for a couple of centuries. But the deeper the dive, the more intractable the problems become.
For one thing, if air is compressed the proportions of its vital constituents change. Most of the air we breathe is nitrogen, a light, normally inert gas. The useful part, the oxygen, is heavier. Nitrogen compresses less easily than oxygen, with the result that if you double the pressure of normal air, the area taken up by oxygen is reduced. At depth air is no longer air as we know it, and any system that delivers breathable gas to divers must take this into account.
Increasing depth leads to another major problem. Under pressure, more gas is forced from the lungs into the tissues and blood. When pressure is reduced again, it escapes, but it may do so with dire consequences for the diver. The deeper the dive, and the longer it lasts, the worse the possible dangers.
It has been known since the seventeenth century that a rapid change from high to lower pressure produces gaseous bubbles in the blood. In the 1870s a French doctor, Paul Bert, explained why. The oxygen is not of immediate concern: the body uses it up chemically. The problem lies with nitrogen. When pressure falls – as a diver rises to the surface – the nitrogen that has been absorbed by the body recombines into bubbles, exactly as bubbles appear in a bottle of a soda water when pressure is released. The amount of gas in the body and the rate at which it turns back into bubbles vary according to the pressure and the speed at which the diver returns to the surface. A gradual return allows the gas to escape naturally. A sudden return brings on decompression sickness, commonly known as ‘the bends’ because of the agonizing twisting and turning performed by a victim as he or she attempts to deal with the pain. Pain in the joints is the prime symptom. But there are many others: pain in the muscles, fainting, vomiting, deafness, paralysis and eventually – if the nitrogen bubbles reach the brain – death.
One seemingly obvious solution to these problems is to increase the amount of oxygen. Not so: pure oxygen breathed at much more than double normal atmospheric pressure is lethal. There was no alternative (until much later) to nitrogen.
On the basis of Dr Bert’s work, the British scientist John Haldane, working from experience, devised tables that related the depth of the diver to the time spent at that depth, and indicated the time needed for decompression. Careful use of the tables enabled compressed-air divers to work safely down to two hundred feet.
Why not deeper? There were, it seemed, practical barriers. One was that at greater depths divers became confused and began to act as if they were drunk. One or two even lost all sense of reality and responded – as if they were on an LSD trip – by tearing off their face masks and drowning. The condition, the cause of which was not known (and even now is poorly understood), was labelled nitrogen narcosis – ‘the narcs’ in diving parlance – or, in the more poetic French expression, les raptures des grandes profondeurs – the rapture of the deep.
Another consideration was that decompression times for great depths stretched out dramatically. To work for a few minutes at three hundred feet a diver would have had to spend many hours decompressing at various stages on his ascent. Time, money and weather would not allow such operations, even if the diver’s physiology would.
In theory there were ways of going deeper – by using another lightweight inert gas, helium, instead of nitrogen. But early experiments with helium had shown that it had its own problems, and it was for this reason that Mike Cox’s instructor tolerated no fools, and constantly emphasized the importance of going by the book.
‘I have seen terrible things, terrible things, lad,’ Wainwright told him. ‘I’ve seen people behave dead stupid and cause deaths. I had a mate in my young days, just after the First World War, and he was brought up a bit quick from a hundred and fifty feet. We thought he’d be all right. Went home to supper. Two in the morning: the bends. Dead by breakfast.’
And again: ‘You watch out for a blow-up, Cox lad. I was blown up once. Tripped on something. On my face. All the air into my legs. Like a balloon. Hup – legs first – popped up like a bloody cork. Lucky it was shallow water. In deep water you get a burst suit, nasty bends, drowning – Christ knows what. Keep your head up and legs laced, then you’ll be all right.’
Mike’s first descent passed off without incident. He was to go off the launch into twenty feet of water. It was midwinter, so he had to wear a woollen sweater, long underwear, a woollen hat and a shoulder-pad to take the weight of the metal corslet that held the helmet. The suit – heavy layers of rubber and twill – pulled on over his feet. Then came the 16lb boots. His assistant piled on the corslet, two weights back and front of 50lb each, and finally the helmet itself, the face-plate open for conversation until the descent started. On land the whole thing was an incapacitating suit of armour weighing about 200lb.
Then the petrol-driven compressors started, he clumped on to the ladder and climbed down into the water. Once submerged, he was released from the suit’s weight. He experimentally regulated his buoyancy by adjusting the exhaust valve in the right-hand side of his helmet. At the bottom of the rope he stood disoriented in the semi-darkness and silence, hearing only the clicking of the return valve in his helmet and his own laboured breathing, until Wainwright took his hand and began to walk him slowly across the bottom of the harbour.
The breathing was easy, but even at that depth the clammy pressure of the water against the diving suit round the bottom half of his body was peculiar. The time of day had been nicely calculated. While he was down there the tide began to turn. Wainwright showed him how to crouch down against the tide and, later, to crawl in order to make headway against it.
Over the next few weeks he dived twice a day, gradually coming to grips with ever more difficult tasks. He learnt to use the rope signals for communicating with the tender above. One pull on the breast-rope for ‘I’m all right’; four pulls on the air pipe for ‘Pull me up!’; and a dozen other signs. He had to manipulate a hammer and chisel to cut through a hawser and to hand-saw through a piece of wood attached to a cable.
The work was intensive and demanding. Physically Mike was maturing fast. The food was good, he was getting a lot of exercise and there was a spring-like toughness about him that would have made him extremely attractive to girls – if he’d had a chance to get to know any. There would have been opportunities. They were
allowed out into the town and knew the locals, though they were beginning to feel themselves an élite and never developed the competitive swilling of pints common to groups of young men. Andy Cunningham seldom went with them: he had his own social contacts and would occasionally vanish for whole weekends. Family, he would say, or friends. But most of the other lads had girlfriends in the town and happily entertained each other with tales of who had done what to whom and how soon after the first acquaintance, and who offered the best return for time and money invested. But Mike was the youngest, the least experienced, and he felt it, and remained silent.
Andy Cunningham, meanwhile, was full of what he was learning in the family home in Hampshire. His father had arranged for him to meet a chap called Crabb (‘A jolly suitable name for a diver!’) who delighted him with stories of what he called ‘human torpedoes’ in and around Gibraltar.
It seemed that some ‘Eye-ties’ had been captured by our chaps sitting on a sort of twenty-foot tube driven by batteries and carrying 500lb of high explosives. The idea was to sneak in over nets and between mines and place charges under British ships. In September 1941 a tanker, the Denby Dale, had been blasted in this way and in December six members of the Italian navy’s special assault unit, the ‘Sea Devils’, did more damage to the Mediterranean fleet than all the rest of Mussolini’s ships had managed in almost two years of war. Dressed in frogmen’s suits and riding their three midget submarines with only their heads showing above water, the men sneaked into Alexandria harbour with some British destroyers, laid charges and crippled two battleships, a destroyer and a fuel tanker. The Italians were all captured; but there was no denying their effectiveness. Crabb and another chap had been given the task of protecting the ships in Gibraltar harbour against any more such attacks. They’d picked up another three human torpedoes, preventing them laying any charges.
Now, said Cunningham – and by this time Wainwright had joined the group – we apparently wanted some human torpedoes of our own.
There had already been one operation with the first two-man ‘Chariots’ in October 1942 against the Tirpitz. Two of them were ferried across the North Sea in a small fishing boat and then towed into Trondheim Fiord, where the Tirpitz, still the most formidable of the dangers confronting the Arctic convoys, was moored. Only bad weather, which snapped the two lines, prevented the attack. The frogmen escaped through Sweden.
Wainwright bent forward across the mess table.
‘Where’d you get all that stuff, Cunningham?’ he asked.
‘Family, sir, family,’ he said airily, as if he were privy to the inmost secrets of the War Cabinet, then conceded: ‘Well, a lot of the details are still secret, I suppose.’
He supposed right. There was already a good deal more to small-scale naval operations than he could possibly have known. Army Commandos in the Mediterranean had set up their Special Boat Sections, whose powerful swimmers and expert canoeists had in 1941 recced Italian-occupied Rhodes and mounted raids on ships and coastal installations around the Mediterranean. Success, and the sheer thrill of such pinprick adventures, attracted the attention of David Stirling, the founder of the SAS, whose D Squadron of canoeists inherited the SBS name when Special Services was reorganized after the North African campaign ended in 1942.
At the same time a number of separate special boat units – canoeists, frogmen, powerful swimmers all – had been trained to mount raids on the coast of occupied Europe. From a medley of commando, SAS, naval and Royal Marine units there would soon emerge the Special Boat Squadron proper, the forerunner of today’s Royal Marines’ SBS, cutting its teeth in the Mediterranean. But in 1942, when Cox first became aware that there was demand for specialists in marine operations, the sea-based raiders were members of private armies, with no unified command.
It was for one of these specialized units that Wainwright was seeking volunteers. The training camp was way up north where nobody could go nosing about.
‘They want four of you chaps as soon as possible. You’ll be one,’ he said, looking at Cunningham. ‘But the rest of you, tomorrow I’ll tell you a bit more about being a frogman. Then I want some volunteers.’
The next morning Wainwright told the twelve young divers something about other aspects of diving. He started by explaining that the trouble with the equipment on which Mike and the others had trained was that it was cumbersome and tied the diver to a surface support system. This disadvantage had long been recognized, and for well over a century divers had been experimenting with equipment now generally referred to as ‘scuba’ – self-contained underwater breathing apparatus.
The first workable scuba was invented in 1825 by an Englishman, William James. In his apparatus a huge belt served as an air reservoir. But the suit was heavy. It had a steel helmet and heavily weighted boots, and was designed for walking on the bottom, not free swimming. In 1865 two French engineers designed a scuba with an air valve that responded to the changes in water pressure and delivered air to the diver’s mouthpiece only when he took a breath. But this early scuba gear allowed dives of no longer than a few minutes and no deeper than forty feet.
The length of time a diver could stay down increased to three hours in the late nineteenth century with the invention of the first self-contained oxygen apparatus, though of course it could not be used below thirty-three feet, the depth at which oxygen becomes poisonous. In the 1930s a Frenchman, Yves le Prieur, invented a suit which consisted of a steel cylinder of compressed air connected by an air hose to a full face mask. There was no regulator, however, and much of the air went to waste. Only in 1942 was this feature introduced, when Jacques Cousteau and Emile Gagnan produced their aqualung. Their invention – or rather their novel application of technology that had been in existence for some time – was to revolutionize free diving.
But the aqualung, even if the Allies could have swung into immediate production, was clearly not suitable for cold North Sea waters, which was the Admiralty’s particular concern at the time Wainwright was delivering his lecture. Cunningham’s information, he said, was good, except that in the future research would be concentrated not on the Chariots but on a more advanced form of underwater assault vehicles known as ‘X-craft’. These midget submarines were later used to launch a partially successful attack on the Tirpitz in late 1943.
But all that was only part of what Wainwright had to say.
‘If you have been following the news,’ he told them, ‘you’ll know that things aren’t looking quite as bad now as they did a year ago.’
Monty had pretty well cleared up in North Africa, he continued. ‘No time at all we’re going to be in Tripoli. The Yanks are pouring men in. Malta seems to be in the clear. Not long now and they’ll be wanting to use North Africa as a jump-off point to invade Italy. There are a lot of ports on the African coast, and Jerry knows they’ll be pretty vital to us. Now, Jerry’s not stupid. As soon as he pulls out of a port, he does his best to block it. Not just mines, but old ships, tankers, dock gear, concrete – anything he can’t get away is blown up and dumped across the harbour mouths. Come the time we want to get in there with some cargo and troop ships, we’re likely to have our bottoms opened up. It’d be like running over a lot of tin-openers. All this business about frogmen is all very well, but I’ve got to get some of you chaps down to North Africa smartish. HMS Nile – that’s the base at Alexandria in case you’re wondering – wants divers for the inshore squadron. But from today your training’s over. You’re divers, whether you feel ready or not. Now, before I tell you what I think, I want volunteers. Questions?’
Mike glanced at Sid Carter.
‘You ask him,’ said Sid. Mike nodded.
‘I like goin’ deep,’ said Mike. ‘How deep can you go with a scuba?’
‘Don’t know, lad. If you can pressurize the canisters properly, three hundred feet perhaps. Trouble is, if you stay down a long time you have to come up slow, and control it yourself. That takes time. Very dangerous, that. No, if you want depth – useful wo
rking depth – you stick to the old hard hat. It’s safe as houses if you use it properly.’
‘How deep will hard hats go?’
‘Depends on the narcs and decompression times. Best dive so far is five hundred feet. But that’s a simulated dive in a tank, using helium. We’ve never talked about that. From that depth it would take bloody hours to decompress – no one knows how long – but at least you’ve got air and time and you’re not expending energy swimming about. You want my guess? In a few years we’ll be taking quick trips down to five hundred feet or so.’
‘What about a thousand?’
‘Only in diving bells and submarines, son. Forget it.’
But Mike knew he would never forget it, and therefore volunteered with Sid for hard-hat work clearing harbours in the Mediterranean.
Just before he went he spent Christmas 1942 with Sid’s parents. The two young men had a week’s leave, and were given travel warrants that would take them to London and then down to Rye and back again, in time for the New Year. Mike had never in his life been down to the south coast. A couple of summers in the 1930s he’d been taken with other families from the East End down to pick hops near Ashford, but they’d always remained inland, among the shacks and the fields.
Along the coast, the noise of war had receded. The bombing raids had stopped, the doodle-bugs were yet to come. There was no shortage of food, though it was mainly fish. There was beer to drink, and Woodbines to smoke. Mike and Sid walked the windswept beaches, smelt the salty mud of the Rother at low tide, took buses into Rye, wandered through the town’s steep, damp, cobbled streets. They made proud contributions to the family budget from their pay packets. They gave, and were given, small presents. They talked and drank with neighbours, and were treated as war heroes. Mike loved it.
It was here, on a windy walk along the shingle, that Mike talked about the Edinburgh again. He relived for Sid the arrival of the gold, the loading, the story of the broken box, the torpedoing and the scuttling, the desolation of Vaenga and Murmansk.