the Perisher course for diesel-electric submarines, since the Royal Navy no longer operates boats of that type. The SMCC is attended by submariners from other navies, including the Royal Australian Navy, the Brazilian Navy, the Royal Canadian Navy, the Republic of Korea Navy, and the United States Navy. Officers of the Royal Danish Navy also attended, prior to Denmark's withdrawal of its submarine capability. Overseas candidates attend the course because its high standards enjoy widespread respect, and because it fosters links between allied navies and the Royal Navy. The SMCC was ISO certified in 2004. Course structure The diesel-electric course is four months long, with a combination of simulator time ashore and sea time under war-like conditions while operating off the coasts of Norway and Scotland. At most, six students will participate, under the tutelage of an instructor referred to as Teacher. The course has four stages, the first of which is training on Dutch Walrus class submarine simulators at Den Helder. The second stage, known as COCKEX (a corruption of the old COQC name plus the standard shorthand for exercise), takes the candidates to sea, where they practise the skills learned in the simulators, along with tactical safety training. They return to the simulators for stage three, where they are taught both the tactical aspects (including rules of engagement, evasion measures, and interception procedures) and personnel management skills (including stress management, maintaining working conditions, and medical skills) of commanding a submarine, while learning other skills required for command. On conclusion, the students return to sea for the 'Cockfight', where Teacher evaluates each submariner's ability to command a submarine independently. During this, the candidates will be run through multiple war-like exercises with little respite between each. One example of the type of exercise, from the 2004 course, required the candidate to take their submarine into a harbour (simulating a naval base) to lay mines, with less than of clearance between the fin and ferries passing overhead, and even less distance between the keel and the harbour floor, while a warship used active sonar to hunt for the submarine. Students who fail the course are, in most cases, no longer permitted to serve on submarines in any capacity. According to Commander Marc Elsensohn, Teacher for the 2004 diesel-electric course, the main reasons for failing are that the candidate regularly loses situational awareness, or shows a narrow focus or over-reliance on one