Cost of new propellers and repairs to Glen Sannox to prevent more hull cracks revealed

The extra work is needed to prevent further hull cracks caused by vibrations that kept the vessel out of action for nearly a quarter of its operational life since it entered passenger service to Arran in January last year.

Industry sources familiar with the situation have told The Scotsman that that scale of work on a brand new ferry is “scandalous”.

The ferry’s’ propellers will have to be replaced because their vibration caused the damage, with the replacements likely to be available in about six months time.

Glen Sannox returned to service on CalMac’s Troon-Brodick route on Monday after four months of repairs and its annual refit, which included extra steel being added to temporarily fix the vibration problem.

Sister vessel Glen Rosa - which will also need new propellers - is due to be completed at the Scottish Government-owned Port Glasgow yard by the end of the year - eight-and-a half years late.

Glen Sannox was six-and-a-half years late and both ferries will together cost some £400m - four times over budget.

Scottish Labour transport spokesperson Daniel Johnson said: “After just a year in service, the Glen Sannox is already racking up millions of pounds worth of repairs.

“Taxpayers, islanders and shipyard workers are all still paying the price for the SNP’s ferry fiasco.”

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Yard chief executive Graeme Thomson told the Scottish Parliament’s net zero, energy and transport committee that he had “high confidence” that Glen Rosa would be completed between October and December, but he could not guarantee it.

However, he admitted some equipment installed on Glen Rosa may not work properly because of the construction delays, which have been extended because of problems being discovered such as corrosion of its stern tubes.

He said: “We don’t know for the thousands of items on there what might fall over.

“We’ve not done that level of analysis but we do anticipate that some equipment will not work effectively and therefore we need a good, slick process with our suppliers to work out where we can secure a replacement for it.”

Yard chief financial officer David Dishon said warranty claims for the propellers and other work on Glen Sannox would reach some £3.2m, which would be funded by the public purse.

He said: “At the moment, it’s £2.2m and it will end up somewhere around £3m to £3.2m.”

Other repairs to Glen Sannox have included its cooling system having to be laboriously cleaned of contaminants.

Anchor equipment is also being replaced by taking it from Glen Rosa after a fault was found during testing.

Committee convener Edward Mountain, who has led Holyrood committee scrutiny of the two ferries over the last decade, said he was “not confident” with the latest completion date and described the repairs process as “a bit of a guddle”.

He expressed his “huge frustration” at the situation, referring to letters to the committee from Mr Thomson last year which had expressed confidence that there would be no further delays or cost over runs.

Mr Mountain, a Highlands and Islands Scottish Conservative MSP who is leaving Holyrood at this year’s elections, said: "I have to say, that doesn't fill me with confidence, it doesn't fill me with any confidence at all.

"I've heard, again, the same thing given and we've ended up with increased costs.

"I have to say that in some ways I'll be glad when I leave this Parliament and I don't have to continue to listen to this, because I'm not convinced by any of the arguments you've given."

Earlier, the committee heard a damning indictment of the way the yard had been run from its new chair.

Duncan Anderson, who was appointed last month, said: “The past management of vessel construction has involved mistakes, largely due to poor or outdated shipbuilding techniques used over several decades.

“The staff have remained hard working and dedicated to their jobs, which is remarkable despite being driven to these poor practices.

“The governance and management of those workers’ tasks has been very poor indeed in the past, and it appears we have built the ships twice.

“The sequencing of processes was historically poorly thought out and poorly implemented.

“This will be our main challenge on Glen Rosa, seeking to dismantle these poor practices and implementing new ones.

“With the appointment of a new senior management team, I’ve seen considerable changes in the yard and much improvement.

“But decades-old problems and neglect of support for commercial shipbuilding in the UK can’t be repaired in months - it will take years.”

Mr Anderson said work on Glen Rosa had “improved a great deal” in recent months but the yard remained in “recovery mode”.

He said the ferry’s hull had been in the water in dock too long, while dormant machinery with the vessel “should have been commissioned a long time ago”.