Can the first mate be the political commissar of the ship?

The first mate can't be the political commissar of the ship. The first mate refers to the ship's pilot who is only lower than the captain. Minister of Deck Department (Driving Department) and main assistant to the captain. Under the leadership of the captain (who is also the political commissar), he is responsible for the overall work of the deck department, performing the duties of navigation duty, assisting the captain in the safe navigation, and being responsible for the cargo handling and transportation maintenance of the deck department.