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Goodbye to Gosport’s iconic SETT


submarine escape training tank
submarine escape training tank

Yet another memorable aspect of 2020 was that the Royal Navy’s world-renowned submarine escape training tank (SETT) in Gosport closed in January, as reported by Scuba Diver. Diving instructor and former Royal Navy submariner Andrew Tonge went to pay a final visit.

the SETT
the SETT

Possibly the most-iconic building in the Royal Navy, the SETT dominates the Gosport skyline. Since it became operational in 1954, it has been viewed with a sense of dread and achievement by thousands of submariners from Britain and the Commonwealth.

But like all who passed through the hallowed gates of HMS Dolphin, its time in the senior service has come to an end. Submarine escape training for the Royal Navy will be carried out at the Clyde Submarine Base in Faslane, Scotland.

Just before the onset of travel and social restrictions due to the coronavirus pandemic, I was lucky enough to have one last look around!

On my visit to the SETT, I was lucky to be be accompanied by former Royal Navy Petty Officer, Alan ‘Goldie’ Goldsmith, an ex-submarine escape instructor and member of the sub-sunk parachute assistance group, or SPAG, as it was known; an elite group of submariners, who are world leaders in submarine escape. They make up the body of instructors at the SETT and the teams that parachute into the sea when a sub is lost, ready to rescue submarine crews escaping from the depths, putting into practice for real everything taught at the SETT.

Royal navy submarine school. Submarine Escape Training Tank (SETT) - Main Entrance
Royal navy submarine school. Submarine Escape Training Tank (SETT) – Main Entrance

There is no doubt about it, the SETT is imposing. It has a distinctly foreboding feel. As military buildings go, with a way of dissuading the unwelcome, this one is right at the top of the list.

The building’s purpose is simply to house a 30m tank of water. Personnel from the submarine service get into the tank via airlocks at various depths and make their way to the surface. It is a cramped and unforgiving experience and, not to put too fine a point on it, it's dangerous. During the SETT's operational years, a number of people have died. It is not for the faint-hearted.

Just being up close to the building itself reminded me of my own escape training here at the SETT as a young submariner. The nerves, the butterflies and a genuine wonder of why I had volunteered for submarines all came flooding back!

Submarine Escape Training Tank (SETT)
Submarine Escape Training Tank (SETT)

Climbing into the lift with Goldie, we made our way to the top of the tank. Coming out of the lift, the sight is quite breath-taking. The tank is essentially a very deep swimming pool, with the water temperature maintained at around 32°C. Looking down I could see the faint shimmer of the airlock doors at 9m and 18m and the two upper lids of the deepest escape chambers, side by side at the bottom, almost 30m below. Showing its age, the light blue circular walls of the tank were carrying a little rust.

When in use, at the top, sits the ‘boss', the officer in charge of the escape training operations. Behind him lies the grim reminder that this doesn't always go as planned – the emergency decompression chamber, available to quickly take a submariner back down to depth for therapeutic recompression, to try to arrest a case of the decompression illness (the bends), where a build up gases in the blood stream and tissues of the submariner, expands on ascent, with sometimes devastating effects.

Around the top of the tank, a series of ladders allows access and egress to and from the water. But of course, other than to practice surface skills, that's not how submariners get in. They get in down there, through one of those airlock doors or the upper lids!


Down at the 9m lock, Goldie and I clambered in. It was even more cramped than I remembered. A class of around ten submariners plus one instructor would escape from here. In effect a box stricture on the outside of the tank, the lock was damp and dark. In an escape, the instructor would shut the outer door and flood the lock. Think of being in tiny room that is flooding. You have no breathing equipment. No regulator. You are wearing a pair of shorts and a mask.

“Take a good, deep, breath!” The instructor calls out and the first submariner takes that breath, ducks under the water and is pulled out into the tank by the instructing staff, lurking outside the hatch, and let free in the direction of the surface.

It's worth noting here that members of the instructing staff make all of their descents and ascents without diving gear. They are freedivers. Travelling up and down (all the way down, to 30m) on a breath. At the side of the 30m chambers, is a diving bell from which the member of the instructing staff work.


Next stop, the 18m lock! This is deep. The adrenaline is pumping. Just getting in again all these years later, I could feel it. I would never like to even contemplate this from a stricken sub. Even in training, the water is still the master. Get it wrong, forget what the instructing staff tell you, and you are in for a bumpy ride. For real, in the darkness and cold on the open ocean, in a compartment crammed with people trying to survive, it doesn't bear thinking about.

I'm quickly taken back to my training. For the trainees that were in the 18m lock, there was no let up. The water level has crushed the air and the pressure is on. Drawing that good, deep, breath, the mask leaks a little, and I feel the panic rising, this is it. I move through the water. It is strange to be passing the legs of my fellow lambs going to the slaughter as I see the door to the lock and the instructing staff diver on the outside. Hands spin me around. I'm facing back into the lock. I am totally confused.

The breath is burning in my chest, now. I feel pulling and jerking, and I am yanked backwards, out from the lock into the body of water in tank. I'm now at 18m, with no diving gear. No BCD and weight system to keep me buoyant. No regulator to keep me supplied with air. I'm in another world now. Thousands of years of evolution is screaming at me to bolt, to try to get out of the water, but the instructing staff diver, calmly floating in front of me, is holding me, jabbing my torso. Yes, breathe out, breathe out. He sees me breathe out, a steady stream, lips no wider than a pencil, as has been shouted at me, for the last few days.

I'm sure that the instructing staff diver is laughing at my eyes which are now so wide that they fill my mask! Then, released, I'm racing upwards towards the surface. The air is gushing out of my lungs, like I'm vomiting gas, and the desire to hold my breath takes over. No, no, no. Do Not Hold Your Breath. Holding your breath means lung expansion injuries which gets you a ride in a Royal Navy helicopter and a nice cool resting place in the morgue at Haslar Royal Navy Hospital (as it was when I did escape training).

Whoosh! I gasp air and realise that I am alive! I am now bobbing on the surface. “Okay, shipmate, over to the side.” Is that it. Don't I get a medal for lunacy!

In true Royal Navy style, the relief, the sense of pride and the sense of one-upmanship that some other poor unfortunate candidate has yet to do it, is soon taken away. With the exercise completed at 18m, it’s time for the trainee submariners to take the lift to the bottom, for the 30m escape.

The access area to the two-person escape chamber (SETT)
The access area to the two-person escape chamber (SETT)

The access area to the two-person escape chamber, is made out as the escape compartment of a sub, cramped, with not even enough room to stand fully upright. After scaling the ladder, into the escape chamber itself, the claustrophobia is palpable. The ultimate, final destination!

The hatch rim is very unforgiving on the shins and hauling myself in without whacking my head of elbows was quite a task. Inside the chamber, closing the lower hatch starts the heavy breathing. For the trainee, this is the big one. Again, I am quickly taken back to when I was in here for real. The second person in the chamber on that occasion was the instructor. With the bright orange escape suit plugged into the air supply, filling the hood, visibility is distorted and the heart pounds.

Then it happens – gushing in, filling the chamber, rising up the body, the water takes over. The instructor operates the flood valve. The trainee can do nothing but face what's about to come. As the water fills the tower, the trainee becomes bouyant in the chamber and when the water and compressed air pressure equals the water pressure, the upper lid of the chamber can be pushed open. The air leaves and water rushes in to make up the space. This whole process is very disorientating.


Once having managed to get out of the chamber, the trainee is met by more freediving instructors, who make sure the trainee is clipped to the ascent wire running to the surface, and then they're off! Thirty meters in about 13 seconds! Trying to remember everything that's been drilled into them – breath normally in the hood. Normally! What!? Flare the legs, look up!

On the surface there is a mix of elation and fear! Lying flat in the escape suit, pulled to the side by the instructing staff, the egress ladder is climbed with wobbly legs. The usual dose of shouting at the trainee ensues, Royal Navy style. Stood to attention, still in shock, the smiles beam on the face of those that can say they've done it!

To get the chance to revisit the SETT was a real privilege and it goes to show our experiences of the excitement of the underwater world, never leave us!

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Picture of Mark Evans
Mark Evans
Scuba Diver's Editorial Director Mark Evans has been in the diving industry for nearly 25 years, and has been diving since he was just 12 years old. nearly 40-odd years later and he is still addicted to the underwater world.
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