The FNL timetable is confusing me too. For normal operation the staffing works like this:
0618 WCK-INV - Wick crew, swap at Lairg with 0700 INV-WCK
0802 WCK-INV - Wick crew
1234 WCK-INV - Wick crew
1600 - Inverness crew from 1041 INV-WCK
0700 INV-WCK - Inverness crew, swap at Lairg with crew of 0618 WCK-INV
1041 INV-WCK - Inverness crew who then operate 1600 WCK-INV
1400 INV-WCK - Wick crew who operated 0802 WCK-INV
1831 INV-WCK - Wick crew who operated 1234 WCK-INV
I queried the FNL with Scotrail on twitter before I saw this thread. Because aside from having more services going north than south (maybe they'll use some of those sidings that are always empty ), if the 0802 Wick->Inverness doesn't run then I don't think it's possible to get a ferry from Orkney and arrive in Edinburgh before about 10pm...