CALMAC ferry services have been plunged into new turmoil as one of its oldest vessels is expected to be forced out of action for a fifth month due to new technical problems.

The 38-year-old MV Hebridean Isles, which has been hit with issues since Boxing Day, was removed from the CalMac firing line on February 16 with freight services providing vital supplies to Arran from Troon suspended.

It was due to return to service on Islay this weekend.

But the vessel has been forced back into dry dock as the vessel experienced what the Scottish Government-owned ferry operator CalMac described as "pitch control issues".

It means that services for longsuffering islanders on South Uist will be cancelled between June 3 and 30.

CalMac are forging ahead with the long-delayed required annual maintenance of MV Finlaggan on June 3, which has been serving on the Islay route.

That means MV Lord of the Isles will be redeployed to operate alongside MV Isle of Arran on a two-vessel service on Islay, which will be a cut the number of passengers and cars that the service is usually able to carry.

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CalMac says that if the Hebridean Isles is back in service before the end of June, the South Uist cancellations will be reviewed.

The option of providing additional sailings on the Sound of Barra and on the Little Minch to support displaced traffic is currently being investigated.

The Herald: MV Alfred made it's first official sailing to Arran on Friday

Meanwhile the £1m-a-month emergency ferry MV Alfred has needed a temporary repair to its thruster.

However, CalMac said that it cannot step in to operate to and from Kennacraig to provide additional support away from Arran, where she is currently working.

The vessel has to operate to either Troon or Campbeltown, meaning she will have to remain providing services to Arran.

Robert Morrison, operations director for CalMac, said: “This was an extremely difficult decision and I understand that this will be disruptive for the local community and for customers who had planned to use this route. I apologise for the effect that this cancellation will have and can assure customers that we are working hard to get vessels back in service."

One ferry user official said: "The will-she-won't she in relation to the arrival of MV Hebridean Isles is a total farce and once again islanders are suffering. South Uist has had more than its fair share of the cuts to services as CalMac once again has to shuffle its pack with a fleet that is just not fit.

"They should not be relying on MV Hebridean Isles if the ferries that are currently still holed up at Ferguson Marine were available when they should have been available five years ago.

"The fact we are having to continue to rely on a decrepit vessel says a lot of the state of the fleet as it is."

When MV Hebridean Isles was removed from services CalMac quoted a fault within the control system meaning a freight service was suspended.

Users were told by the Scottish Government-owned ferry operator that an "appropriately qualified engineer" was expected "as quickly as possible".

The lifeline service to Brodick on Arran, one of the busiest on the west coast of Scotland, had remained a one-vessel service as MV Hebridean Isles was unavailable for passengers and concentrating on providing freight services. MV Alfred began on the Arran route two weeks ago.

The Herald: The Arran CalMac ferry, Caledonian Isles pictured departing Brodick on Arran...Photograph by Colin Mearns.29 November 2022.For The Herald Magazine, see story by Mark Smith.

Concerns were previously raised about disruption being felt across the network as the depleted ageing fleet was redeployed to try and cope with the loss of both MV Hebridean Isles and 30-year-old MV Caledonian Isles to passengers.

The latest issue appears similar to that which kept it sidelined at the start of May. Then the issue was described as a "pitch propellor issue".

It had been expected to support services to and from Islay with the MV Isle of Arran for an overhaul for two months from February 5 as part of the rejigging of the network through the state-owned service's programme to improve fleet sustainability through its overhaul programme.

But neither vessel was able to make it.

The latest issues come as island services on Mull and Iona were plunged into a Bank Holiday weekend "free-for-all" after ferry operator CalMac indicated they had no hope of honouring bookings on a beleaguered island service.

People travelling between Oban and Craignure on the island of Mull, were told on Saturday that "due to reduced capacity" all sailings would operate on a "turn up and go basis".

It meant that while tickets were valid on Saturday they were not guaranteed to be on the sailing that they booked for - while some had to queue for hours to get a ferry later than intended.

Complaints were raised about cancelled bookings, and hours of waiting, as others abandoned efforts to go via Oban and made a 100-mile detour to reach the island via Lochaline.