How long does it take for the third-class captain to be transferred to the fourth-class captain?

Three years. It takes three years for a third-class captain to be promoted to a d-class captain. After getting it from the crew service book, you can take the first-class inland river ship pilot (three pairs) for two years. The maritime department organizes training twice a year, and the training time is about three months. The captain is the supreme commander of this ship. In China, the captain and the chief engineer, the first mate, the second mate, the third mate, the second mate, the second mate, the second mate, the second mate, the second mate, the second mate and the second mate are also called senior crew members, and so are German and Japanese countries. In Britain and America, the captain does not belong to the crew, but is regarded as a profession alone.