What is the main job of a seafarer? Please return if you know, thank you.

The daily work of seafarers a *** is divided into two pieces, to the deck as a boundary, above deck collectively referred to as the deck department, the deck department of the crew of the day, including the helm, observation of the radar and electronic charts, and then the two ships intersected by the use of the international common signaling flags and signal lamps, the deck below a cabin, the engine room there are a number of instruments and equipment, such as the main turbine, the deputy turbine, the main boiler, auxiliary boiler, etc., the instruments and equipment is to provide normal power for the ship, the engine department of the daily work is to maintain, repair, and monitor these instruments to ensure that they work properly. These instruments and equipment is to provide normal power for the ship, the engine department to get the crew's daily work is to maintain, maintenance, and monitoring of these instruments, to ensure that they work properly, but to become an international seafarer is to have the relevant qualification certificate, with the start to have a driver's license, no certificate is to be to nautical colleges and universities to learn to get a certificate, do not know whether the owner of this point know that, I am seafarer, vacation in ...