A spare ferry that operates Scotland's most southerly island year round ferry route (peak times) on the Clyde, the MV Isle of Arran, has according to CalMac, since last week temporarily taken over an overnight freight run in the Western Isles.
This is to provide essential freight cover between Ullapool and Stornaway, the capital of Lewis and Harris in the Outer Hebrides.
Isle of Arran is providing two freight sailings while the MV Loch Seaforth is being replaced. Afloat adds the Loch Seaforth is the largest ship in the Scottish state run operator, and which was built by the same shipyard of Irish Ferries cruiseferry W.B. Yeats.
The MV Isle of Lewis was previously carrying out this Western Isles service - however, the ferry is unable to continue to do this as it cannot maintain three return crossings in 24 hours due to crew availability. CalMac cited last Friday, that it will continue to operate the day services.
Specialist engineers are currently working on the Loch Seaforth engines in a yard in Greenock, on the Clyde and with the ferry back in service as soon as possible.
CalMac added this will mean that one ferry will be serving the Ardrossan-Brodick (Isle of Arran) route from this Thursday, 29 April, the MV Caledonian Isles, until a timescale for repairs has been confirmed.
Additional capacity will be provided by doubling up sailings on the Claonaig-Lochranza route during this time.
Passengers who have already booked sailings between Ardrossan and Brodick during this period will be offered alternative sailings as a priority. Space will be limited on 30 April and 1 May.
The 'summer' ferry service to the Mull of Kintyre through Campbeltown (from Ardrossan), which was set to restart on 29 April, has been suspended to accommodate essential demand elsewhere.
These changes were made by using a route prioritisation process which allows CalMac to move ferries around to where demand is most needed when there is extra pressure on the network.
The possibility of hiring a vessel on a temporary basis has been explored but unfortunately, none are available at short notice. This includes the Pentalina which is not going to be free for a number of weeks. Afloat adds this ferry is a former Pentland Ferries that served the Orkney Islands.
Robbie Drummond, Managing Director of CalMac, said: "It is vital that a freight service is provided on the Stornoway-Ullapool route and this movement of vessels is necessary to provide this.
"This situation is far from ideal, and we apologise for how these changes will affect passengers. We will endeavour to offer alternative sailings to everyone who has already booked tickets between Ardrossan and Brodick.
"We know how disruptive this will be for customers and we will keep everyone informed of any further developments. Thank you for your patience at this time."