Ferguson's set to install over 15km of pipework on unfinished ferry MV Glen Sannox

She returned to the Newark yard last week after a three-week period of remedial work was carried out at Dales Marine in Greenock.

The dry dock period was the first major milestone in Ferguson’s revised programme to complete the two dual fuel ferries, which almost sunk the now-nationalised shipyard after the contract ran into big trouble.

It included the replacement of the mis-manufactured bulbous bow, paint repair, removal of marine growth from the hull, external welding and installation of the starboard door.

Bosses say the dry dock inspection demonstrated that the hull is sound.

Tim Hair, turnaround director at Ferguson Marine, said: “Following a period of uncertainty due to Covid-19, it has been really gratifying to see our team return to outdoor working on MV Glen Sannox.

“We’ve made some solid strides forward over the last few weeks on MV Glen Sannox and slightly extended the dry dock period to take advantage of the stability of the vessel whilst stationed there to carry out some additional tasks.

“Now that the ferry has been brought up to its current condition and has returned to our shipyard, the next steps will include work on the superstructure, electrical work and the installation of approximately 16km of pipework.

“While our office-based colleagues have continued to work from home throughout lockdown, making good progress on design and planning, the dry-docking period marked a key milestone in the project and in getting a substantial proportion of our yard workers back to the task at hand.

Glen Sannox, which was launched nearly three years ago, is due for delivery between by June 2022.

Her sister, hull 802, is due for handover to CalMac between December 2022 and February 2023.

The original cost of the £97m contract has at least doubled and a parliamentary inquiry into the affair recently finished its evidence-gathering, with a report by MSPs expected before the end of the year.