All theory exams, the old Part A, as listed by crecord are, indeed, good for life. Engineering Knowledge, General, Motor and Steam are valid for 5 years, but once the appropriate Certificate is gained, they are valid for life.....maybe.
If your CoC has expired and you have no approved sea service in the preceding 5 years, you may have to write one of these EKs again, or take an Oral in lieu of Qualifying Service. You'll have to do a MED refresher and retake the PPS at the appropriate level, too, in that case. Renewal of Engineering Certificates of Competency is covered in the Marine Personnel Regulations, section 107, which you can see here:http://laws.justice.gc.ca/eng/SOR-2007- ... 1-gb:s_104
You need 12 months' sea service in the last 5 years or 3 months in the last 12 months. There are provisions for Superintendants, Examiners, Surveyors etc. and it's all covered in MPR 107 (3)
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