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A stock image of a submarine's periscope

Perisher Course

Image Credit: | Above: A stock image of a submarine's periscope

The Royal Navy's training course for prospective Submarine Commanding Officers is recognised as one of the most intense military training schemes anywhere in the world. Candidates chosen for the course have at this point reached the highest position possible before taking command.

So it's a great honour to be selected, but also quite a risk, because this is a do or die course. Pass the course and you go straight on to take a command role, starting with an XO or Executive Officer job, second in command to the CO (Commanding Officer) and very much in command when the boss is off shift. Most will go from there to becoming fully fledged COs. But if you fail, your entire submarine career is over and you'll never again serve on a nuclear submarine – the Submarine Service doesn't want Perisher failures on its boats!


Originally known as Perisher, the name came from the frequent use of periscopes, but the course retains its nickname because of its sheer difficulty, the high standards expected and the failure rate of individuals. Early in the history of submarines a member of the British referred to their use as Underhand, unfair and damned un-English (Admiral Sir Arthur Wilson, 1901). But as it became clear how brutally effective they could be, the Royal Navy embraced this new technology and in 1917 began the Perisher Course to train submarine commanders. Over its history this brutal course has had a 25% failure rate.

Since 1995, as the Royal Navy phased out diesel-electric submarines, the course has been run to train commanders for nuclear powered submarines. The course has become famous worldwide and many other nations now operate their own versions of Perisher.

The Course

The course runs for five months either once or twice each year. The first four months mainly consist of classroom and simulator training. In the simulator, working with a team of experienced submariners the students must learn to deal with any possible scenario they may face at sea. It's rare for a student to fail at this stage. In the final four week sea phase it really becomes do or die. Around the clock, day and night, the students take turns commanding a real nuclear submarine under their teacher's watchful eye.

The Teachers are always chosen from the Royal Navy's best and most experienced commanding officers. There are the instructor and mentor but also the man with almost sole discretion to pass or fail. During the constant, often hair raising exercises, Teacher will only intervene if he sees real danger to the submarine and its crew or other vessels. But the course is so intense, and the dangers of things going wrong so real, that these interventions can be regular occurrences.

The students are repeatedly expected to make accurate split second decisions in high stress situations. Day and night exercise attacks by ships, aircraft and other submarines all add to the pressure. Above all, they must keep the submarine safe and use cunning to defeat their adversaries. The challenges are sometimes daunting.

Walking the Gangplank… Perisher's tradition for handling an unsuccessful student is not to make him aware of his failure until the last possible moment. The unfortunate student leaves the submarine immediately and his entire underwater career is over.

To the Winners the Spoils… If they haven't already been asked to leave, the remaining trainees don't know if they've passed or failed until the very last day at sea. For those that pass, the reward is command of a nuclear powered submarine they can call their own.

So why does the Navy spend millions of pounds to run this extraordinary course each year, knowing that at best only four are likely to make it through? It's because they reckon this is the toughest, most important job in the whole armed services.