FURTHER delays have been confirmed to the completion of one of the years-late and over-budget ferries being built in Port Glasgow - while the total cost for the two vessels could now exceed £400m.

Ferguson Marine chief executive David Tydeman has told Scottish ministers that MV Glen Rosa will not be delivered until May 2025 at the earliest - three months later than previously planned.

The shipyard boss wrote to Edward Mountain MSP, convenor of Holyrood's net zero, energy and transport committee, today to update the timeline as he also revealed that the capacity of each passenger ship may be significantly reduced from 1,000 to 852.

The CalMac ferries were originally estimated to cost £97m but Mr Tydeman confirmed around £185m has been spent already, with £240m still needed - meaning they could be more than four times the initial budget.

In the letter, the CEO referenced 'design gaps, associated re-work and surprises' as the reasons for the cost and delay issues.

A 'worst-case' scenario of up to £30m for additional costs may also be needed to finish the ferries.

Greenock Telegraph: David TydemanDavid Tydeman (Image: George Munro)

Mr Tydeman said: "These vessels are complex, and I have openly expressed my view that the £97m original contract price was understated and inflation issues have become a significant factor from the longer build period.

"Our revised budget and timelines for Glen Rosa [Hull 802] assume we can transfer the learning from Glen Sannox, improve and refine the solutions we are agreeing with MCA (Maritime and Coastguard Agency) for Glen Sannox and ensure early agreement of compliance for Glen Rosa.

"We have some opportunity to do things better and more efficiently on Glen Rosa, for example, small changes in the location of the new staircases and doorways because less has been built to date."

Safety regulators the MCA ordered changes including wider corridors and extra staircases, while discussions are ongoing about about 11 'vertical exit routes' from below the car decks on the ships.

Greenock Telegraph: Glen SannoxGlen Sannox (Image: George Munro)

Glen Sannox, which will serve the Ardrossan-Arran route, is expected to go into dry dock this Christmas before sea trials next spring.

Mr Tydeman added: "It would be very unusual if there are not issues of equipment or systems failing or breaking or highlighting some specification changes needed, particularly with the first-of-class aspects of the LNG (liquefied natural gas) system.

"Our ability to guarantee completion by March 31, 2024, will thus depend on how well the trials progress and we will make every effort to prove the ship and solve issues as they arise."

Mr Tydeman also apologised for 'significantly understating' the total forecast cost to complete Glen Sannox, which still needs at least another £130m.