A contract to build two ferries for CalMac at Shipbuilder Ferguson Marine's base in Port Glasgow has been hit with spiralling costs and significant delays, with the shipbuilder now threatening legal action. 

Shipbuilder owner Jim McColl estimates that the final bill of the contract could run over budget by as much as £50m. 

The contract to build two ferries will see the first ship, the Glen Sannox delivered in the middle of next year, more than a year later than planned.

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The vessel is the first of two being built as part of a £97m contract from Caledonian Marine Asset Limited (CMAL), a company owned by the Scottish Government that buys and leases ships to CalMac.

The delays have been blamed on CMAL requesting changes to the original proposed design, with Ferguson Marine now threatening legal action over the additional work. 

Speaking to STV News, Mr McColl said: "This is a real albatross around our neck.

"If we could just wave a magic wand and get rid of those two vessels that would be a godsend to us because they've just been a headache from day one.

"I think we're probably running between 40-50% over budget which amounts to roughly £40-£50m."

 "We've documented over 600 design changes.

"Now, some of those are down to us, but a good chunk of them that have impacted the schedule and the cost are as a result of changes requested by CMAL.

"The design of the propellers, the ultimate overall length of the ship, we've been changing quite a bit from the beginning."

Mr McColl added: "You would normally expect a lot of design development work to be done prior to a specification going out, but when the specification went out for these vessels, with hindsight there wasn't enough detailed work done.

HeraldScotland:

"We're having to effectively do that development work on the hoof rather than designing out from a well thought through specification.

"In the past CMAL have refused to engage with us in discussions about any changes.

"We get told it's rubbish or similar dismissals just to go away and that's just not the way to conduct a commercial arrangement."

Mr McColl also denies that the shipbuilders underbid for the contract.

He confirmed Fergusons have been working with consultant to assess the changes and the impact they have had on delivery. 

CMAL insists the work is covered by the original contract, and Ferguson Marine is liable for the additional cost.

Mr McColl continued: "We were asked in the invitation to tender to work with the buyer in a collaborative and innovative way, which indicated that we would be working collaboratively through it to overcome issues.

"But the magnitude of the changes that have had to be made are way beyond what anyone could have anticipated at the time of bidding.

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"So we did bid what we felt was the right price at the time and we were comfortable we would take on the contract and work through it.

"We have made a number of changes to the design, but the response time to agreeing to those changes has been quite long, so that has dragged out the length of time it takes to build them.

"With what I know now, I would not have taken on that contract because I would have insisted on a lot more development work being done for the spec, but at the time we were looking to put work into the yard." 

It has been reported that the ferries were first designed to run on both diesel and liquefied natural gas, however, according to reports, the gas option has since been ruled out as the routes are not suitable for such fuel.