THE Glen Sannox, one of the delayed ferries being built at Ferguson Marine, has left its shipyard berth in order to begin sea trials.

The ferry, which will one day take passengers to and from Arran, left the Port Glasgow yard on Tuesday – heading to a nearby dry dock.

It is expected to begin longer voyages up and down the Clyde on Wednesday and Thursday.

The beginning of the manufacturer’s sea trials marks an important milestone for the project to build two new ferries for CalMac’s fleet.

Costs for Glen Sannox and sister ship Glen Rosa have more than tripled to at least £360 million and they are expected to be delivered around six years late.

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Further tests will need to take place before the ferry, which has capacity for 852 passengers, can begin serving the island route.

It remains unclear when Glen Sannox will be handed over to its owners, as earlier this month the chief executive of Ferguson Marine said there had been delays in installing parts of the ship’s liquified natural gas (LNG) system.

Both ships were designed to be “dual fuel” – running on LNG and traditional bunker fuel in order to keep emissions down – but David Tydeman told MSPs the delays had forced the shipyard to bring in an alternative supplier.

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

Responding to news of the sea trials, chief executive of ferry operator CalMac Robbie Drummond said Glen Sannox would be one of several vessels joining the fleet in the coming years.

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He said: “We are very much looking forward to welcoming MV Glen Sannox into the CalMac fleet.

“She will provide much-needed resilience to the Arran community, and will be the first of the six large vessels and 10 small vessels joining us over the next five years.”

Gary Cook, senior organiser at the GMB trade union, said the government should continue to invest in the nationalised shipyard by ordering smaller vessels at Ferguson Marine.

He said: “No one, apart from the islanders who have waited far too long, want these two ferries completed more than the workers.

“They have been blameless throughout this work and their skill and commitment is beyond question and they now want to ensure taxpayers begin to get value for money from their yard.

“That depends on securing a pipeline of work, starting with the small ferries.

“It makes no sense for a private operator to profit from the investment that has gone into this shipyard after all the pain that has been endured over the current contracts.”