Fishing Boat Blueprints Why Would A Captain Of A Fishing Boat No Longer Be A Captain?

Why would a captain of a fishing boat no longer be a captain? - fishing boat blueprints

I am investigating a plot to a film. It is a fishing village. I need someone who was once a captain of a fishing boat, but no more. Anyone can), the story is probably of a "return join" (why always the master of a ship?