Passenger disruption on CalMac’s most popular route will be prolonged again after a new setback to lengthy repairs on one of its oldest ferries, The Scotsman has learned. Caledonian Isles, which has been off the main Arran route since January, is not now expected to return to service until next month - more than a week later than expected. One islander said Arran had already endured a “long and challenging summer”.

Damage to a water tank has put back the 31-year-old ferry resuming Ardrossan-Brodick sailings once more after steelwork repairs costing some £5 million to the vessel’s hull were extended from June to the end of August . The vessel is now expected to be carrying passengers again in the second week of September following its return from dry dock in Birkenhead on Merseyside. During its absence, capacity on the route has been reduced and some sailings switched to Troon, increasing journey times, while stand-in ferry Alfred has been deployed in its place, on charter from Pentland Ferries in Orkney.

Alfred has operated along with the route’s secondary vessel Isle of Arran, which cannot use Ardrossan in strong easterly winds because of the poor state of the harbour . A CalMac spokesperson told The Scotsman: “Caledonian Isles required additional unplanned repairs to the water ballast tank, which was over-pressurised following completion of the original repairs. “This has resulted in a delay to her return.

We expect her to be ready for transit on September 7,.