The first of Scotland's ferry fiasco vessels will not be up and running until October, at the earliest.

It has been confirmed that the target for the Glen Sannox handover for use by ferry operator CalMac will not be until July 31 - after more months of delay.

But once handed over, there will be a two month period where CalMac will carry out crew familiarisation and network trials.

It comes as John Petticrew, the new interim chief executive of nationalised shipyard firm Ferguson Marine admitted that the installation and commissioning of the 'green fuel' liquefied natural gas (LNG) remains "particularly challenging".

He said: "An underestimation of the complexity, the degree of difficulty of the installation, the lack of available expert knowledge and qualified resources in the UK in relation to marine LNG systems, has disappointingly contributed to futher slippage in the progress that we have been able to make in the last few weeks, and consequently our previously proposed schedule."

Ousted chief executive David Tydeman was fired last month after a tumultuous two years at the helm of the nationalised shipyard as he warned of yet more delays to delivery.

It means that Glen Sannox will not serve Arran for the peak summer season. It might be available for the end of the current CalMac summer timetable on October 20, but users are not holding their breath after a series of delays.

Both Glen Sannox and sister ferry Glen Rosa, still to be completed at Ferguson's were due online in the first half of 2018, with both now due to serve Arran, but will be over six years late, with costs expected to be quadruple the original £97m contract.

One user group official said: "Another day, another farce. It feels like it is never-ending. "We keep getting promises and promises of its arrival and every time they are broken.

READ MORE: Anger as ministers plan to make ferry firm CalMac 'arm of government'

"The service is failing badly, and it was always hoped that we might at least get Glen Sannox for much of the summer. But now that is not the case and it sometimes does make you wonder whether it will ever see service."

Nationalised Ferguson Marine, which is building two wildly delayed and over-budget ferries for operator Calmac warned at the end of December that there could be a further delay of two months as it was facing "supplier issues" which is delaying the commissioning of the vessels' LNG propulsion systems.

A further delay was going to push back the completion of Glen Sannox beyond a scheduled date of March, and would be expected to affect sister vessel Glen Rosa’s arrival on May 2025. Glen Rosa is expected to face further delays.

The Herald:

Before December's supplier issue, Ferguson Marine were working to a planned acceptance date for Glen Sannox of March 31 for Glen Sannox - which was two days after the summer timetable for 2024 was due to begin.

That would have meant that the first vessels would be ready to use for Arran at the end of May, as after handover CalMac need two months to carry out preparations for taking on passengers, including familiarisation training and safety drills.

Mr Petticrew said: "We appreciate and fully understand that there will be disappointment in all quarters, and particularly in Arran, for this further delay. "

The Scottish Government has previously said all systems – including the LNG propulsion – will need to be completed before the state-owned ferry and port-owning agency Caledonian Maritime Assets Ltd can take delivery.

Plans for the introduction of the 'eco-friendly' vessels had already been thrown into new chaos as it has emerged two key Scots ports will not be capable of providing the 'green' fuel.

In what was described as a "new ferry shambles", the Scottish Government confirmed that there is no budget to provide the necessary port facilities for LNG at either Ardrossan or Troon in 2024/25.

The Herald: CalMac

The Scottish Government-owned ferry operator CalMac has already been planning to use Troon rather than Ardrossan for the two ferries that will serve Arran. That was when it was hoped that the first of the vessels would be ready for passengers in the Spring of last year.

The dual-fuel ferries which were meant to be identical, were lauded by then First Minister Nicola Sturgeon as the 'sustainable' ferries that would "contribute to Scotland's world-leading climate change goals".= They were hailed as a step towards a greener future for Scotland's state owned CalMac ferry fleet as they were to be the first UK-built ships capable of running off liquefied natural gas, or LNG, as well as conventional diesel.

Glen Rosa was meant to be delivered to CalMac in August 2018 and Glen Sannox, was launched by Nicola Sturgeon nearly seven years ago.

The dates of arrival have been constantly in a state of flux as their construction has been plagued by design challenges, cost overruns and delays.

Scottish Conservative shadow transport minister Graham Simpson MSP said: “This latest delay is yet another huge blow to Scotland’s betrayed island communities.

“It means that – after testing – another whole summer season will have gone by without desperately-needed new CalMac vessels being in operation, thanks to the SNP’s monumental incompetence.

“That’s another peak holiday season for hotels, restaurants and businesses completely at the mercy of a decrepit fleet that simply can’t be relied upon.

“Scapegoats come and go at Ferguson and CalMac, but still no SNP minister has carried the can for a national scandal entirely of their making.”