One-minute showers, a message from family once a week and a pong to wilt your periscope - what it's really like to spend seven months UNDERWATER on a nuclear submarine

With a sense of disbelief, I waved to my children through the February drizzle. I was not going to see them again for ten months.

My mission as captain of HMS Turbulent was taking me to sea until December — a 286-day submarine deployment, with only brief stopovers to break up the voyage.

The regrets were pushed to the back of my mind from the moment I was aboard 'Turbs', a nuclear-powered Trafalgar-class attack submarine with 130 men — crews were single sex back then. There is no time for any of the crew to dwell on the family life they are leaving behind.

Coming back to the real world after months at sea is just as disorientating. The crew of HMS Vengeance, one of Britain's four submarines armed with Trident nuclear missiles, will have experienced it recently as they returned to home base at Faslane in Scotland after a reported 201 days at sea without any break at all.

I'm a veteran submariner, with 23 years service, but the thought of that makes me quail.

Ryan Ramsey is a former navy commander and was the captain of HMS Turbulent. He is a veteran submariner with 23 years of service

HMS Turbulent is a nuclear-powered Trafalgar-class attack submarine with 130 men

Communal games such as cards and a Navy game called Uckers, a sort of Ludo with added strategy, are popular on board

What hits you first when you surface after weeks under water is the sea smell, that bracing combination of brine and fish. There's none of that in the submarine itself.

Then you realise how strained your eyesight has become. Distance vision inside a submarine quickly atrophies, because it is never used.

That is even more noticeable after a voyage than the brightness of the sunlight.

Every crew member in a sub plays a crucial role. We all have our individual jobs, precision components in a complex machine. The captain has to be aware at all times of what everyone is doing.

By comparison, real life seems chaotic and messy. I remember standing on Plymouth high street, a few hours after disembarking, and feeling bewildered — who were all these people, and how could anyone keep track of so many lives?

These feelings soon ebb away, but they are a symptom of how intense life is under the sea. The crew live in the closest of quarters, with no privacy and no respite, sharing food, bathrooms, toilets and sleeping quarters.

Emotions become magnified, with the incessant threat of attack or ambush by an unseen enemy.

We are always hunting and being hunted. I liken submarine warfare to a knife fight with an unseen opponent in a pitch-black room — neither knows where the other is, but a single wrong move or even a clumsy sound could be fatal.

I had my fair share of terrifying encounters with hostile submarines — but details of those remain classified.

But around once a month during my deployment, we'd come dangerously close to another submarine — it's easy to do since the vessels are so quiet — and we'd have to execute our Close Quarters Drill to avoid a collision.

It's a well-rehearsed routine. Sonar operators get to work reporting the bearing of the other sub, while the tactical systems guys work out its course and speed. Then the Watchleader (the person leading the team), starts changing course to avoid collision.

When collision is avoided, they'll attempt to regain control of the situation — you're in a dog fight at this stage (if you've watched Top Gun, that's when you're trying to position yourself behind the 'enemy').

Sealed within a 280ft metal tube, deep below the ocean surface, our lives were also in danger from any number of engineering failures. Turbulent's ten-month mission in 2011 came close to disaster when our air conditioning broke down in the Gulf of Oman.

Emotions can become magnified on a submarine, with the incessant threat of attack or ambush by an unseen enemy

Submarines are self-sufficient, apart from the need to take food supplies on board: the air is recirculated, the power source is nuclear, but waste water does have to be discharged overboard

Every crew member in a submarine plays a crucial role - they all have their individual jobs and are precision components in a complex machine

About three hours after sailing out of the United Arab Emirates port of Fujairah, the temperature on board began to rise sharply. Outside, the water temperature was 37C. Inside, the air felt as though it was boiling, with humidity of 100 per cent and the thermometer hitting 60C very quickly, heated by the machinery and the nuclear reactor.

The crew began to drop from heat exhaustion. Some were seriously ill and many more were fighting to stay conscious. We lost so many key players in a matter of minutes, but the training worked, the team functioned and people stepped into positions where they would not usually operate. 

Our only hope was to dive into the coldest depths with no sonar operating and hydraulics in reserve mode.

That cooled the submarine enough for engineers to be able to diagnose the problem: barnacles blocking the coolant inlet pipes. We clear these by blasting compressed air through them. By now we had 27 casualties, five of them in a bad way, with one whose life was in danger.

We radioed for medical aid and surfaced — at first, my heart sank as I looked through the periscope and saw nothing but empty sea around us. I thought our message hadn't got through. Then, to my relief, I realised the helicopter was directly overhead. The crew member was airlifted to safety.

Any Royal Navy ship can suffer a breakdown at sea but the problems are multiplied when the boat is operating underwater. On one patrol, our sewage system malfunctioned, which was not a pleasant experience.

Only two toilets — or 'heads', in naval parlance — were operational, both in the officers' quarters. When 130 men are sharing two toilets, the queues are endless. Even when everything is working, there are only nine toilets and ten sinks on an attack submarine.

Tougher still, there are only three showers. Time management is crucial, and so is water conservation. Submarines are completely self-sufficient, apart from the need to take food supplies on board: the air is recirculated, the power source is nuclear, but the waste water — or black water, in nautical parlance — does eventually have to be discharged overboard. 

Discharging dirty water makes a noise. That noise can give away the position of the sub. It's vital that the crew use as little water as possible, so showers are used infrequently and quickly.

A submariner will turn the water on just long enough to get wet, then turn it off before applying shampoo and soap. Then the water goes back on just long enough for a rinse, and that's it. Anything longer than a minute in total is known as a Hollywood shower, resulting in a lot of mockery and derision.

Inevitably, with 130 crew and a lot of machinery in such a confined space, there's a distinctive smell to a submarine.

Mixed up in that is a combination of roll-on deodorant and old-fashioned body odour, overlaid with a scorched smell of engine. It's an acrid tang, but you rapidly cease to be aware of it. It was worse when the engines were diesel electric, but it hasn't altogether vanished in the nuclear era. You get used to it, because it's pervasive.

Because there's no privacy on board, crew members have to learn to live with each other

There's no space for individuals on the submarine. Everyone is committed to the success of the mission, and in many ways everyone is equal, writes Ryan Ramsey

The sense of community and camaraderie is like nowhere else in the Royal Navy. 

When I was Operations Officer on HMS Talent in 1999, the boat's patron Princess Anne came aboard with us. Her visit lasted only three hours but later, we received a message from Admiralty HQ, thanking us for looking after her. It came with a note to say that 'the princess now smells of HMS Talent'.

During my 23 years, I served on exchanges with the Royal Netherlands Navy, the U.S. Navy, and went aboard Polish, Portuguese and Canadian subs among others. The one constant was the tightness of the teamwork.

When people ask, as they often do, what possessed me to devote my life to submarines, that's the answer — the chance to be part of a team like no other. It's as tight as the closest family.

The first day I ever went aboard a submarine, I was an 18-year-old midshipman at naval college on a training day, and the experience blew my mind. 

It wasn't only being inside the most complex machine the British military possesses, or the excitement of being underwater, but the professionalism of the crew working as a seamless unit.

I knew that day it was exactly what I wanted to do.

First I had to complete my general training but the ambition never left me, and after a couple of years I joined the Submarine Service. That was nearly 35 years ago, and I still have close friends among the crew I first served with.

Life on a submarine is nothing like being on a warship. On a frigate or a destroyer, there's much more space as well as a more pronounced hierarchy: the captain has his own chef, for example.

On a submarine there's one galley for all, with the same menu: fish on Fridays, steak on Saturdays, roast on Sundays, never changing. Officers and other ranks eat together — and that applies to every aspect of life.

As a consequence, the sense of community and camaraderie is like nowhere else in the Royal Navy. There's no space for individuals. Everyone is committed to the success of the mission, and in many ways everyone is equal.

It doesn't matter whether you are a commander, a lieutenant, an able seaman or an electrician, you all do the same training and earn the same qualification, known as your 'dolphins'.

That's a great leveller.

Because there's no privacy, you have to learn to live with each other. That doesn't mean everything is always sweetness and light. Human beings will have arguments, but we have methods for managing that before it boils over.

My view as captain was that the healthiest thing was to let arguments play out, to release the tension. Bearing grudges is strongly discouraged. We air our problems and move on.

Boredom is the worst cause of friction, and the daily routine is calculated to make boredom redundant. The watchkeeping cycle is six hours on, six hours off. During hours of duty, the crew are completely focused on their tasks, for example when we're preparing for strike operations or gathering intelligence.

During the other two periods, everyone has to eat and sleep.

On a Trafalgar-class submarine, there are 95 bunks for 130 men so some rotation or 'hot-bunking' is inevitable.

Usually, there's no more than 90 minutes of recreation time. Some people watch DVDs or listen to music on headphones, but communal games are more popular — cards, and also a Navy game called Uckers, a sort of Ludo with added strategy.

Increasingly, the lack of mobile phones can be a culture shock at first for new crew members. Again, people adjust quickly, and soon come to appreciate the lack of external 'noise'.

The greatest frustration is the lack of news from home. The boat receives a regular short electronic message from headquarters, a short burst of information about two pages long, transmitted either as a very low frequency or an ultra-high frequency signal.

This contains a round-up of the week's headlines, for general consumption. But each crew member also gets a weekly 'familygram', which used to be 150 words but is now longer, from their loved ones.

It was my job to vet these, to ensure no one on my crew received bad news that could distract them from the job.

Submariners have to sign up to this. They all understood that I might know things about their lives that I couldn't tell them.

On one very difficult occasion, I received word that a crewman's father had died unexpectedly, a week into the voyage.

I had to speak to him 20 times a day, but I couldn't give any hint of the tragedy.

On the day before the boat returns to dock, the captain has to call individuals to his cabin, one by one, and deliver the bad news. For me, that was the toughest part of the role. I hated the responsibility.

Once those messages are delivered, a message is broadcast to the whole crew, to say, 'That's the end of the bad news.'

The ability to cope with that uncertainty is part of what makes submariners such a special breed. Anyone of an anxious disposition could drive themselves mad worrying about what might be going on back home.

But I almost never saw that happen. In this hyper-intense, isolated environment, every member of the crew knows they have a vital task.

Once you're in a submarine team, you're in a unique family.

Submarines are the first and last line of defence for the UK, and that functions only if everyone pulls together.

Ryan Ramsey is a former submarine captain and the author of A View From Below