Delayed Glen Sannox ferry sets sail for crucial sea trials

Delayed Glen Sannox ferry sets sail for crucial sea trials New CalMac ferry Glen Sannox has begun some of its final sea trials before being handed over by the Ferguson shipyard.

The long-delayed ship will be put through its paces using liquefied natural gas (LNG) to power its engines for the first time.

Despite a last-minute hitch that forced a further two-week delay, the ship was last week loaded with the fuel, which needs to be kept at minus 162C.

Glen Sannox is currently scheduled for delivery 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 ferry procurement body CMAL and several weeks of crew familiarisation trials by operator 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 an acrimonious contractual dispute between CMAL and the shipyard's former owners.

Glen Sannox is the first ship ever built in the UK capable of running on LNG as well as conventional marine gas oil.

But the technology has added a lot of extra complexity for the Port Glasgow shipyard, and many of the delays have been linked to the LNG systems.

One former Ferguson Marine boss described the challenges of packing the equipment into the tight spaces as more complex than designing a Navy warship.

The most recent delay was caused by difficulties achieving low enough temperatures for the fuel to be loaded at Greenock's Inchgreen Marine Park, where Glen Sannox has been moored.

Earlier this week, the shipyard announced that after four-and-a-half days of cooling it had successfully completed the refuelling operation.

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."

Methane slip The main benefit of LNG fuel is that it is seen as cleaner burning, releasing fewer pollutants such as nitrous and sulphur oxides.

The engines also emit up to 25% less carbon dioxide when running on LNG although some have questioned the green credentials of the technology.

There is a risk of "methane slip" - the release of unburnt gas during certain operations - and methane is itself a particularly harmful greenhouse gas.

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 the ship's main harbour at Ardrossan, but plans to redevelop the port have stalled.

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 - and four slightly smaller ferries using more conventional propulsion systems are being built in Turkey.