The long-delayed ferry MV Glen Sannox will begin timetabled sailings on 13 January, CalMac has announced.

The ferry operator confirmed the vessel would enter official passenger service on the Arran route after successful tests and crew familiarisation over the past month.

Glen Sannox will run on the busiest route on the CalMac network, operating between Troon to Brodick.

It had been scheduled for delivery in 2018 but endured considerable delays due to major challenges in design and construction, in what became a long-running political row.

Costs on the ferry increased from an initial contract price of £97m to more than £400m, £45m of which were government loans never fully recovered.

A soft launch of the ship is expected in the week of 6 January, with occasional sailing once or twice a day, before the full passenger timetable launches the following week.

Scottish government Transport Secretary Fiona Hyslop said confirmation of the Glen Sannox’s arrival was “welcome news”.

She added: “This new vessel will support the people of Arran and wider ferry network.

“She will deliver increased capacity on the busiest route on the Clyde and Hebrides network, and we can all now look forward to her bringing benefits to our island communities and ferry users.”

Duncan Mackison, CalMac’s CEO, said: “The feedback from our crew has been that the vessel is performing well, and there is real excitement across CalMac about getting her into service and serving Arran.”

CalMac also confirmed that MV Caledonian Isles, which operates from Ardrossan to Brodick, should return to service in time for the next summer timetable, on 28 March 2025.

The vessel has re-entered drydock for several weeks of steel renewal works, which will be followed by realignment work and sea trials.

Mr Mackison added: “There has been understandable concern about the future of MV Caledonian Isles but her future prognosis is good and we are increasingly confident she will return to serve Arran in time for our busy summer period.”

Plans are for Arran to have a two-vessel service to Brodick, with MV Glen Sannox from Troon and MV Caledonian Isles from Ardrossan, starting on 28 March 2025.

Since the Glen Sannox was launched the Ferguson Marine shipyard where it was built has faced administration, nationalisation and years of delays as it struggled with complex engineering challenges to complete the dual-fuel ship.