Until the end of November there are special sailings from the Isle of Harris to North Uist, operated by the chartered MV Alfred, to support the Leverburgh to Berneray route where the ferry has ongoing engine problems- https://www.calmac.co.uk/tarbert-lochmaddy-november-2023.
This is a port pair which are very rarely linked.
But these sailings can be cancelled at short notice if the Alfred is required to cover as relief vessel elsewhere in the network (as this weekend, where she has been diverted to Arran, in the Clyde, due to a problem there).
... and so the game of musical chairs continues into the winter for poor CalMac.
The Lochmaddy (North Uist) to Uig (Skye) route is also diverted (to Ullapool) currently due to harbour extension work at Uig.