How to fill in the crew service qualifications in the new crew service book?

You should be a crew member of a river boat. According to the regulations, the minimum manning is two drivers and one engineer. At the same time, if the continuous sailing time does not exceed 8 hours, 1 driver can be exempted. This is divided into two situations. First of all, if there are two drivers on board, fill in according to who is the driver who plays the role of "captain". The so-called "captain" role is which pilot is responsible for managing the ship. To put it bluntly, the person who is mainly responsible for sailing on the ship is to see who is the boss. In many cases, the boss is also the navigator. Second, if there is a driver, the only driver who signs the captain's signature in the service book. You don't understand. In fact, it is the captain (with the captain) or the crew who plays the role of captain. I hope you can understand.