Complex sentence: Each winter since her introduction, "Clansman" has relieved the larger Calmac units for their annual refit, leaving the route she was built for leaving Oban, Castlebay and Lochboisdale back with MV Lord of the Isles.
Split into simpler sentences: Each winter since her introduction, "Clansman" has relieved the larger Calmac units for their annual refit, leaving the route she was built for. Leaving Oban, Castlebay and Lochboisdale back with MV Lord of the Isles.