SHIPBUILDER Ferguson Marine Engineering Ltd last month launched legal action against the publicly owned Caledonian Maritime Assets Ltd in a row over a £97 million contract to build two new dual-fuel “eco-ferries” for the Clyde and Hebrides Ferry Service.

MV Glen Sannox is due to go out on the Arran-Ardrossan route, while the other vessel, known as 802, is supposed to be for the Uig-Lochmaddy-Tarbert triangle. Both ships look set to be months behind schedule.

Central to the dispute is the cost of building the two new ferries.

Ferguson Marine Engineering Ltd (FMEL), which is part of Jim McColl’s Clyde Blowers, is seeking compensation from Caledonian Maritime Assets Ltd (CMAL) .

It claims that since it won the contract back in 2015, the operator has demanded hundreds of design changes be made to the ships.

McColl said previously this was costing him tens of millions of pounds.

He 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 have 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 more than 600 design changes.”

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

The Scottish Government loaned FMEL £45m to help cover the expense.

Dual fuel means the 100-metre passenger and vehicle roll-on roll-off ferries should run on a low-carbon system of diesel electric and battery power.

Transport Scotland says the ferries will be significantly cleaner and better for the environment.

That point has not gone unchallenged, however, with recent research claiming that dual-fuel vessels produce greater levels of emissions of methane.