SCOTLAND’S island communities face widespread disruption next year as two £50 million hybrid green ferries will be delayed by complex engineering works required on the pioneering vessels.

First Minister Nicola Sturgeon will today launch the MV Glen Sannox in Port Glasgow, the world’s first liquified gas duel fuel ferry, which was due to start on the busy Arran route from next summer.

But it has been revealed the new hybrid ferry and its sister ship which is due to run on the Skye to Harris route, experiencing technical issues at the Inverclyde town’s Fergusons yard and neither is now expected to enter service until 2019 or even 2020.

It comes amid concerns that a 10-fold increase in traffic is causing severe problems for island communities and the two new 334ft-long vessels would have increased capacity across the over-stretched network.

Figures show the number of motorhomes travelling to the Western Isles has risen over the past decade, with nearly 2,000 heading to Harris alone.

The huge rise in tourists follows the introduction of a Scottish Government scheme to make island ferry fares more affordable.

The Road Equivalent Tariff (Ret) was introduced to boost remote economies – and worked so well the number of cars on one route is up by more than 80 per cent.

Ret bases fares on the cost of travelling the equivalent distance by road and was introduced on the Western Isles, Coll and Tiree in October 2008, cutting fares by up to 55 per cent.

It was extended to Islay, Colonsay and Gigha in October 2012, to Arran in October 2014 and now covers every route.

Across the network, car traffic has increased by just over 25 per cent which is causing severe problems as islanders struggle to book ferries and increased traffic contends with many single track roads.

But “highly challenging” engineering issues with building the UK’s first ferries to run on both liquefied natural gas and marine gas oil means the new ferries which are aimed at easing congestion may not be ready until 2019.

Ferguson Marine chief executive Jim McColl highlighted the “extremely complex” difficulties involved in the “exciting and ambitious” build is disrupting the original timetable.

He added: “Highly challenging engineering issues arising from the unique nature of the dual fuel ferry project presents unforeseeable challenges.

“However, the experience and knowledge gained during this project will be of enormous benefit to the competitiveness of Scottish shipbuilding in the future as technology continues to develop to meet tightening clean energy legislation.”

Transport Minister Humza Yousaf said: “It’s disappointing to find out the new ferries will be delayed.

“The vessels have important roles to play, not just providing a vital link between the islands and the mainland but also allowing CalMac to reconfigure their fleet around the Clyde and Hebrides network to the benefit of other communities.

“It is now important that all parties involved in the project refocus and make sure the ferries are delivered to this new timescale.

Mr Yousaf is commissioning a review by an industry expert into the delays to “explore whether any time can be recovered and seek more specific delivery dates for the two vessels”.

The £48million ferries will be owned by Scottish Government company, CMAL, which will lease them to Cal Mac.

Both vessels will have a lifetime of over 30 years and could operate in a wide number of harbours and routes.

Designed to run on either marine diesel or LNG gas, the more efficient engines will cut down on CO2, sulphur and nitreous oxides emissions.

Arran community councillor Neil Arthur said: “Any delays in this will be disastrous for us here on Arran and across the entire network. We need to know what the technical issues are because we cannot have even more reliability issues with the services and again rely on old and inefficient boats.”