ARRAN'S long-awaited new ferry has finally begun full sea trials before being handed over by shipyard Ferguson Marine.

As revealed earlier this week, the Glen Sannox finally has its liquefied natural gas (LNG) propulsion system up and running.

The vessel is currently scheduled for delivery to operators CalMac by mid-October.

The ship underwent its first successful sea trials earlier this year, but only running on conventional fuel because the LNG systems had yet to be commissioned.

Ferguson Marine said the latest tests would last two or three days to evaluate manoeuvrability, acceleration and speed.

This will be followed by "owner's trials" with procurement body CMAL and several weeks of crew familiarisation trials by CalMac before it carries its first passengers.

The ship was originally due for delivery in 2018, but has been beset by a series of problems including design difficulties and contract rows.

But the vessel won't be running on the main Arran route from Ardrossan. Instead, it will operate from Troon Harbour - at first.

READ MORE: Ferry disruption fears

It won't be able to operate from the North Ayrshire port until the Ardrossan Harbour upgrade is completed.

And while the upgrade was approved by the Scottish Government a full six years ago, work has yet to begin.

Scottish transport secretary Fiona Hyslop ordered a review of the project costs last November. And, allegedly due to a row over who pays for what amongst the partners involved, it has not yet been given the green light.

Andrew Milligan, head of engineering at Ferguson Marine, said: "The successful LNG bunkering is a highly significant milestone as it’s the first time it has ever been done in the UK.

"It was a complicated process which required significant safety protocols to be put in place.

"We experienced some unexpected challenges around this process and, unfortunately it has had a knock-on effect to the handover schedule."

The LNG fuel will also have to be imported from Qatar and driven to Scotland from Kent in south east England using diesel road tankers.

The plan is eventually to have dedicated fast LNG refuelling facilities built at Ardrossan harbour.

Glen Sannox will initially sail to Arran from Troon instead, and be refuelled directly from road tankers.

Its sister ship, Glen Rosa, is due for delivery next year.