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After the STCW-BT (Basic Training) course is completed, the staff will need to 'revalidate' their training certification by completing a refresher course (24 hour STCW-BTR), every five years. Designed for personnel who have previously completed a 40 hour Basic Training course and have NOT completed one year of approved Sea Service within the last five years.
The Training Resources Maritime Institute (TRLMI) in San Diego CA is a good facility to take these classes.
https://www.maritimetrainingschool.com/basic-training (STCW-BT)
https://www.maritimetrainingschool.com/basic-training-refresher (STCW-BTR)