The hugely-delayed Ferguson Marine ferry Glen Sannox has been delayed by another three weeks because of further problems with installing its dual fuel system, the yard revealed on Friday. The difficulties with the liquefied natural gas (LNG) equipment, which will be used to power the CalMac vessel along with traditional diesel, mean its July 31 delivery date has been put back to at least August 19. Advertisement Advertisement Sign up for the latest news and analysis about Scottish transport Thank you for signing up! Did you know with a Digital Subscription to The Scotsman, you can get unlimited access to the website including our premium content, as well as benefiting from fewer ads, loyalty rewards and much more.

The news comes three days after Economy Secretary Kate Forbes told MSPs that when she met yard chairman Andrew Miller and interim chief executive John Petticrew a few weeks ago, “both of them confirmed to me that they see no change to the commitment to deliver the vessel by the end of July.” The ship for the main Arran route to Brodick - CalMac’s busiest - should have been completed six years ago. Its cost has quadrupled, although no further increase was announced on Friday.

The shipyard also said work on sister vessel Glen Rosa was “not at the rate we would like to see”, but did not signal any delays or cost increase. Mr Petticrew told MSPs in his latest progress update on Friday: “The LNG system has been well documented as the biggest challenge we were.