MV Isle of Arran is covering services on the Stornoway-Ullapool route today (Tuesday).
MV Isle of Lewis remains in Stornoway with a technical fault which has been identified as an electronic control system issue. Specialist engineers are currently investigating.
Calmac are unable to give a timescale for repair of the problem but apologise to customers for inconvenience caused.
The fault it not thought to be connected to previous technical problems.