sentences:  The seamen often served in the navy six months over the summer of every third year.Later, from the middle of the 18th century, some of the "rotar" in the cities would pay a fee equal to the approximate cost of providing a boatsman, instead of providing one from among themselves.There were several problems with this system, relating to the fact that a large proportion of the seamen did not live anywhere near the largest naval ports of Stockholm, Gothenburg, and Karlskrona.