The inside or lower hatch is opened first and a man crawls up into the tube. He breathes off a breathing umbilical (BU), a mouthpiece connected by a rubber tube to the sub, utilising the sub’s air. The lower hatch is closed and the tube is flooded. When the pressure in the escape-hatch equalises with the outside, the top hatch opens and the man exits. When he is free, the upper hatch is closed again, the water is pumped out, and the lower hatch can then be opened and the cycle repeated. This is the basic concept for the SBS exit, but with a few variations.
Depending on the task, such as a maritime anti-terrorist assault, the SBS man wears a lightweight nylon dry-bag over which he straps a multi-pouched vest containing everything he needs for the assault – spare weapon magazines, explosive entry devices and grenades, climbing equipment, personal waterproof radio, knife, pistol, any ‘special devices’ and a climbing harness. The primary weapon, the MP5, is strapped down one side or across the front of his body on a quick-release hook and his pistol is fixed into a holster on his lower thigh or hip. On top of all of this he carries his diving equipment, which includes fins, mask and a small air-bottle of only ten minutes’ duration at surface pressure called a RABA (rechargeable air breathing apparatus) which has a male connection that plugs into the large air-reservoir bottles outside the sub for recharging. The bottle is small simply because a larger one would not fit into the escape-hatch along with the diver.
The first SBS operative climbs up through the lower hatch, which can be a tight squeeze with all the equipment, and if he’s a big lad he may have to be pushed up from below. Instead of using the escape-hatch and releasing only one man at a time, the SBS adapted many RN subs (all O-class, electric/diesel silent types) by having the one-man tubes replaced with ‘five-man chambers’ (it was a tight fit for four men) which looked something like an external Calor-gas storage tank of a diameter just large enough for a man to sit inside in the foetal position. The team climb up through the escape-hatch and then manoeuvre into the chamber one by one and sit alternately opposite each other with their knees curled up in front of them. When the last man is inside he crunches up over the others while the lower hatch is clanged shut. He can then sit back on the hatch giving the others a little more room to breathe and remove equipment from uncomfortable places like colleagues’ gun-barrels and radio antennae from out of noses.
A dim light in the ceiling of the chamber is all there is to see by and a push-button intercom positioned at the waterline is the only communication, other than a small signal hammer in the event the intercom should fail. Six breathing umbilicals hang from the walls at intervals – one is spare. Each diver tests his BU and gives a thumbs-up when happy. The diver near the intercom informs the sub when they are ready to flood. Then the sea-water gushes in.
A combination of pressure and clashing temperatures creates a mist which decreases visibility. As the water comes up your body you breathe normally through your BU. You keep a mental note of where the spare BU is in case yours fails, and you watch the man opposite in case he has a problem.
The water floods the chamber to about four inches from the top of the tightly curved steel roof (waterline) leaving a small air-space. An instinct is to keep your face out of the water in this narrow air-pocket, but it’s easier just to sit there, like a sardine, head under the water, in the cramped blackness, and wait. You might be out in five minutes, or you could be stuck there for half an hour. Although it’s crowded, you’re in your own world in the watery darkness. It’s like being in a coffin after the lid has been nailed firmly shut, the coffin has been lowered into the ground and six foot of earth has been piled on top while you stay calm inside. And you have about as much chance of getting out quickly if something goes wrong. Your life is entirely in the hands of the captain. This is not a good time to succumb to claustrophobia. The trick is to clear your mind, keep still, and think pleasant thoughts while you wait for a signal from the casing diver that he’s ready to open the outer hatch and let you out.
On one occasion, during the flooding of a chamber I was in, it was the first ‘run’ of the day and the pipes had just been flushed with hibitain, a pipe-cleaning chemical. The pipes are supposed to be flushed clean with water after the hibitain, but on this particular day this had been overlooked. As the chamber flooded it started to foam up until the air-space was nothing but dense soap suds. I now know what it would be like to sit inside a crowded washing machine.
Before the first operative exits the flooded chamber he removes his BU and replaces it with the mouthpiece of his RABA and turns it on. He is then guided out of the chamber by the casing diver and directed along the top of the submarine casing to the ‘lurking area’, where he plugs his RABA into one of the larger air-bottles and waits for the others. If there is a problem now he has hours of air to breathe. Each member of the team goes through the same process.
When the entire team is out of the chamber and assembled in the lurking area, the signal is given and they follow guidelines along the casing, up the fin to where the periscope is, where they can ‘let go’ of the sub to continue to the surface. If this is a conventional operation such as an assault on a coastal target, the casing diver would have already released the team’s stores, such as inflatable boats and their engines, from the special bins under the casing. On the surface the team pull cables connected to gas-bottles that automatically inflate the boats. By the time the SBS team is in their boat or boats and ready to head for the shore ten or twenty miles away, the casing diver has ‘tidied up’, re-entered the sub and it has left the area.
Many years into my career in the SBS, during a day of E&RE with my own team, one of the sub’s crew, a young submariner, was so impressed with the process he could not do enough for us. In fact we were so godlike to him that he elected to be our manservant. We didn’t mind.
When it was time to exit the sub he would be there, in the torpedo compartment, to assist with our equipment. On re-entering he would take our wet gear away as we undressed to hang it up and would have a hot mug of tea waiting. He insisted if there was anything we wanted to make our stay more comfortable we need only ask and he would gladly oblige.
‘Dig-out, pal,’ we told him.
The second day, after we re-entered, he could not hold back the reason for his awe any longer and emotionally declared, ‘You blokes are amazin’. I don’t know how you do that. You couldn’t pay me enough. I can barely swim a width of a swimming pool under water.’
We felt he was being a little over the top, but we accepted the adoration nobly.
‘’Ow you can ’old your bref in that tiny li’l chamber while it floods an’ nen climb out ’en swim to the surface is fuckin’ staggerin’.’
We looked at him oddly. ‘What do you mean, hold our breath?’ I asked.
‘What sort a trainin’ you do to ’old your bref for so long is beyon’ me.’
‘We don’t,’ I said. ‘We breathe off the sub when we’re in the chamber.’
His brow furrowed and he leant forward as if not hearing me quite right.
‘Wha’?’ he said.
‘We breathe off the sub. And before we exit the chamber we breathe off these miniature air-bottles,’ I said, showing him one of the RABAs.
He looked shocked. ‘You wha’?’ he said. ‘You mean you don’t ’old your bref?’
‘No.’ I laughed. ‘What the fuck do you think we are, sea lions?’
He looked really disappointed. ‘You mean you don’t do it all in one bref?’
‘Sorry, mate,’ I said.
‘Wankers,’ he exclaimed. ‘Wha’ a bunch a fuckin’ tossers. My grandmuvver could do ’at.’ And he stormed off and we didn’t see him again for the rest of the operational cycles.
Much of the pioneering work for E&RE is carried out by the SBS in the sea lochs of Scotland. The lochs are calmer than the open sea but they have their own dangers and one in particular is most unpredictable, and was the cause of a fatal accident the day I approached the submarine rehearsal area in the fleet tender.
Inland lochs are fresh-water and the sea lochs, as their name suggests, are sea-water, but not always precisely so. Freshwater streams flow down from the mountains and into the sea lochs in many places and sometimes the fresh water holds together as a large body, not immediately mixing with the sea-water. Fresh water is less dense than sea-water and therefore does not support or float an object, such as a submarine, quite as well. When a submarine suddenly plummets due to hitting a less dense patch of fresh water it is called a ‘depth excursion’. It’s a bit like suddenly going over a waterfall you didn’t know was there in the dark. A depth excursion is only a momentary inconvenience for a submarine, but for a diver, outside on the casing, it can be lethal.
There are two points of buoyancy that most affect a diver: positive and negative. A diver in an air-filled suit rising to the surface without power is lighter than the water he displaces, and is positively buoyant. If he is pulled down under the water towards the bottom of the ocean, as he descends, the pressure acting on him increases until he reaches a point beyond which he will no longer have to be pulled down and will sink of his own accord. At this point he is described as being negatively buoyant. The point between positive and negative buoyancy is called neutral buoyancy.
A diver, in a dry-suit, wearing a lot of equipment, such as weapons and climbing gear, will need to release some air into his suit from a small suit-inflation bottle attached to his waist in order to maintain his neutral buoyancy, otherwise he’ll sink.
When a diver is on the casing of a submarine for E&RE he can be anywhere between thirty to sixty feet below the surface (sometimes the subs lose finite control of their depth and sink below periscope depth). He will release enough air into his suit from the small suit-inflation bottle to make sure he is neutrally buoyant at that depth. If he’s too positively buoyant he’ll have to hang on and pull himself along the casing of the sub in the hand-stand position which looks and feels stupid, and if he should lose his grip he’ll float away and ‘lose’ the submarine. With the correct buoyancy, when he’s ready to surface, he releases the submarine and gently fins his way up, growing more positively buoyant as he rises due to the reduction in pressure and therefore the expansion of the air in his dry-suit.
On this particular day, there were three divers getting ready to exit the chamber of HMS
Orpheus
, which was cruising at periscope depth below the surface of Loch Long – a sea loch. Of the three SBS divers using the chamber that day I knew only one, Chris, the operative who first welcomed me to the squadron. Another was an officer called Jim and the third was an NCO named Huk.
As I approached the area in the tender, although the submarine was unseen below the surface, I knew where it was because of the Zodiac safety boat, a giant-sized rubber inflatable boat used just for this purpose. It contained the dive supervisor, standby diver and safety diver, and moved silently along without its outboard engine running because it was tied by a line to the sub’s periscope, the tip of which was only just visible on the surface several metres ahead of the Zodiac. A second inflatable was circling the area half a mile away to ward off any local boat traffic. My tender slowed and came alongside the safety tender which shadowed the party several hundred yards aft. I would have to wait until this serial was over before I could join the sub.
A diver can comfortably move about the outer casing of a sub if its speed does not exceed half a knot. Any faster and he has to concentrate on holding on. Faster than two knots and he cannot hold on at all because of the force of the water pushing against him. The initial danger if he lets go is that he will pass through the props. When a sub hits a fresh-water patch and takes an ‘excursion’ it uncontrollably increases in speed and loses depth until the commander either blows its ballast tanks or steers back up. There are many dangers for a diver during an excursion, perhaps the greatest one being that, when the sub ‘drops’ suddenly, it takes him below his point of neutral buoyancy making him negatively buoyant. Communications between divers and sub are difficult and therefore it is often impossible for the commander to know precisely where the men are outside.
As the serial progressed, those of us on the surface were initially unaware that the sub had cruised into a fresh-water patch and begun to dive uncontrollably – the periscope suddenly dipping out of sight for a moment was not unusual. Huk was the lead diver and was coming out of the chamber at that exact moment. He had removed the sub’s BU from his mouth and was breathing off his RABA set. The sub takes a moment to build speed and the initial moment of an excursion is not always obvious to the diver. But as Huk cleared the hatch he felt his ears pop. The same team had taken an excursion to eighty-five feet a few days earlier without incident, so the experience was not new to them. The casing diver, aware himself by now of the excursion, signalled Huk to make his way to the lurking area, where he could plug into the large air-bottles and recharge his RABA. It was dark, but Huk could make out the light-coloured jackstay rope that led along the casing to the lurking area. Chris and Jim continued to exit the chamber and were preparing to transfer from the sub’s air to their RABA sets. There was no immediate concern as they expected the sub to ascend back to its cruising depth eventually as it had done the previous day, but this was a much more serious excursion than anyone could tell at that initial moment. The first people to realise how potentially dangerous it was were those on the surface.
The safety boat, attached to the periscope, suddenly plunged nose-down into the water like a giant fishing float attached to a 1,000-ton fish. The diving supervisor, standby and safety diver were literally catapulted out of the boat like rag dolls as it went near vertical to follow the submarine down. But before the huge rubber safety boat disappeared below the surface the line ripped from its nose under the tremendous strain and it shot backwards almost completely out of the water. Its heavy engine, attached to the back, almost came down and hit one of the safety crew in the water. The second inflatable sped to help the standby crew, but there was nothing anyone could do to help those below. They were on their own.