Submarine Command Course The Submarine Command Course ( SMCC ) , previously known as the Commanding Officers Qualifying Course ( COQC ) , and informally known as the Perisher because of its low success rate , is a training course for naval officers preparing to take command of a submarine . Created by the Royal Navy during World War I , the course was originally intended to address the high attrition rate of submarine commanders , as the previous method of handing down knowledge from officer to officer was prevented by wartime deaths . Following World War II , the Royal Netherlands Navy became involved in the course ; the Dutch later partnered with the British to run the course , and following the British conversion to a fully nuclear submarine fleet , took over responsibility for running the course for diesel - electric submarines . Officers from other nations regularly participate . The four - month course is run in four stages , the first and third involve learning ashore in simulators , while the second involves learning at sea . The fourth phase is the assessment , during which the candidates ( of which the maximum is six ) show their ability to command a submarine unaided during war - like conditions . The success rate for the SMCC is only 70 % and , on failing , candidates are prevented from serving on submarines in any capacity . Formation and history . Prior to World War I , knowledge relating to command of a submarine was passed on from a boat ' s commander to his replacement . However high attrition rates during the war meant this training could not always be passed on , and the less experienced submarine commanders were in turn more likely to make errors resulting in their death and the loss of the boat . In 1917 , the Royal Navy established the COQC for potential commanding officers . Following World War II , the Royal Netherlands Navy began to send officers to the course . Until 1995 , the Royal Navy and Royal Netherlands Navy were jointly responsible for running the SMCC . Following the Royal Navy Submarine Service ' s transition to a nuclear - only submarine fleet , the Dutch took full responsibility for running the SMCC for diesel - electric submarines . The SMCC was ISO certified in 2004 . The SMCC is attended by submariners from other navies , including the Royal Australian Navy , the Brazilian Navy , the Royal Canadian Navy , the Royal Danish Navy ( prior to their withdrawal of their submarine capability ) , the Republic of Korea Navy , and the United States Navy . 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 practice 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 his 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 . The course ' s nickname of the ' Perisher ' comes from the low success rate of 70 % , combined with the fact that 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 tool or aspect of operations . Making mistakes does not cause a student to fail automatically , as long as the mistake is recognised and corrected before the submarine is endangered . If a candidate fails the course , the submarine surfaces and the submariner is removed by helicopter or boat at the first opportunity .