A boatman is a man whose work is small boats: you pay him to take you out, or to let you use a boat. At a lake or tourist river he may row you across, steer a little ferry, or rent boats by the hour. The word is old and plain, more at home in travel writing and stories than in a job advert. It points to a man; English also has boatwoman, though many people now just say the person who runs the boats. He is not a navy officer and not someone on a huge ship. Though actually, sailor is the wider sea word; boatman stays close to rivers, lakes, and hired boats.