Glasgow And Ships Of The Clyde

Glen Sannox is the first dual fuel ferry built in the UK capable of running on both marine gas oil (MGO), a form of diesel, and liquefied natural gas (LNG).

When running on gas the ship's engines are quieter and emit far lower levels of exhaust pollutants known as NOx and SOx.

The climate change credentials of LNG, however, are questionable as the engines also release methane, which is a greenhouse gas far more potent than CO2.

The LNG fuel also has to be imported from Qatar and trucked up to Scotland from a terminal in Kent.

Despite being a high-sided vessel Glen Sannox is highly manoeuvrable and should be better able to cope with stormy weather conditions off Scotland's west coast.

But the size of the ship means it is currently unable to berth at Ardrossan, the closest mainland port to Arran, unless agreement is reached on a multi-million harbour redevelopment.

In addition to Glen Rosa, four other large CalMac ships are being built by a large shipyard in Turkey - though they are also delayed, by about six months.

The first of those ships, MV Isle of Islay, should be delivered in the spring, with the others following on about four months apart.