Complex sentence: Løwenørn, a Danish mariner, described in year 1791-1803 this part of the Norwegian coast, and he tells that Kvernberget was used in this way by the navigators on board of ships just outside Trondheimsleia.
Split into simpler sentences: Løwenørn, a Danish mariner, described this part of the Norwegian coast in 1791--1803. He tells that Kvernberget was used by the navigators onboard ships just outside Trondheimsleia.