DISRUPTION to Arran's ferry network is “inevitable”, the operator has said, with the ageing vessel serving the Ardrossan to Brodick to be out of action until at least mid-November.

The 31-year-old MV Caledonian Isles usually serves the route - which is Scotland's busiest.

The vessel was due to return to service this month, though a further delay is now expected.

A CalMac spokesperson said: “Unfortunately, MV Caledonian Isles may be out of service until mid-November. We have identified that the clutch outer sleeve in the port gearbox is damaged and must be replaced.

"Spares have been ordered but they are on a long lead time, and we're looking at alternative options to replace the damaged parts. We have also identified the need for repairs to the starboard stern tube.

“MV Caledonian Isles is scheduled for her annual overhaul between January 6, 2025, and February 3, 2025.

“We are reviewing the works scheduled for this window and where feasible will complete as much of this work during the current repair period as possible in the next few weeks.

"The vessel will still require a short period in dock in the new year, but where possible, we will reduce that window as much as we can by carrying out planned works between now and mid-November.”

The ship has been out of service since January for major repairs, with its return delayed multiple times.

West Scotland MSP Jamie Greene described the latest setback as "another huge hit to a ferry network on its knees".

He said: "This will only create more chaos for ferry users, CalMac staff, and islanders.

“The continued absence of the Caledonian Isles will impact the entire ferry network, not just the Arran route. With the Hebridean Isles also set to retire in November, spare capacity and resilience in the network will be zero.

“This means vessels will need to be juggled between routes, resulting in unscheduled cancellations across the network. Dedicated CalMac staff who work so hard to keep the ferry network afloat now face the prospect of operating the system without two major vessels.

“The constant news of delays and breakdowns we are seeing is down to years of SNP underinvestment in our ferry infrastructure, and as the ageing ferry fleet falters it is island and coastal communities who face increasing isolation as a result of this neglect."

Late last month, the ship filling in on the Brodick to Arran route – the MV Isle of Arran – was also taken off the run for annual maintenance, causing disruption across the west coast network.

As a result, operator CalMac has extended a temporary deployment plan until the end of the summer timetable on October 20 and warned of regular reviews of the timetable and which vessels operate on which routes.

“We did anticipate a difficult winter, with our major vessels spending a record number of days in annual maintenance, and it is shaping up to be just that,” said CalMac interim chief executive officer, Duncan Mackison.

“The combination of MV Caledonian Isles ongoing technical issues and the start of this year’s maintenance window has created a perfect storm for ferry services.

“We have a baseline deployment plan for the winter timetable period which allows for MV Caledonian Isles being is in service.

“Now, we are likely to have to regularly review where vessels are deployed to try and maintain services across the whole west coast.”

He added: “Our priority is to keep communities on the network informed of our plans, and meet service demands wherever we can.

“However, it is in inevitable there will be some disruption and on behalf of CalMac I apologise for that.”