CALMAC have confirmed the ageing MV Hebridean Isles will run between Ardrossan and Arran from Thursday after the route's two main vessels were sent to the repair yard.

But there will be no sailings from Ardrossan Harbour on Wednesday, with passengers directed to Troon instead.

As revealed on Tuesday, the island service was hit with a double whammy this week.

The MV Caledonian Isles returned to the Clyde after being out of action for nine months - only to fall foul of a gearbox problem before even entering service.

And the MV Isle of Arran - operating on the route as its replacement - went in for its annual overhaul on Tuesday.

From Wednesday, the Hebridean Isles, normally running to Islay, will relocate to the Ardrossan-Brodick route.

The 39-year-old vessel is due to retire from service in November. In August, the ferry operator said that given her age and general condition, significant works had already been identified for overhaul were she to enter it.

MV Isle of Arran, top, and MV Caledonian IslesMV Isle of Arran, top, and MV Caledonian Isles (Image: Newsquest) The latest problems to the Arran route were raised in the Scottish Parliament on Tuesday, with MSP Katy Clark describing it as "a national emergency".

READ MORE: MSP calls the Arran ferry crisis 'a national emergency'

CalMac said in an update: "MV Isle of Arran, which has been operating on the Ardrossan-Brodick service, must commence overhaul and will be removed from service. The timing is challenging, however, this overhaul cannot be delayed due to the vessel's certification dates.

"MV Alfred, which continues to operate between Troon-Brodick, will operate an additional sailing on Wednesday, September 25. However, please don't present for travel on the Troon - Brodick route without a confirmed booking.

"Understandably, the service will be busy over the next few days, and travel cannot be guaranteed without a confirmed booking in place." 

From Thursday, September 26 to Wednesday, October 2, MV Hebridean Isles will operate the published Ardrossan-Brodick summer timetable.

CalMac continued: "On Thursday, September 26 in particular, given the forecasted easterly winds, this service will be liable to disruption or cancellation at short notice.  

"Weight restrictions will be in operation on MV Hebridean Isles due to an issue with the stern ramp. This means some commercial traffic will be diverted to Troon rather than Ardrossan, and some non-commercial traffic will be diverted to Ardrossan rather than Troon. 

"Lifeline traffic has been prioritised on sailings from Troon today."

For more details and updates visit CalMac's website here.