UNION bosses have warned that the Scottish Government’s problem-hit ferry contracts could be further held up as crews will need “advanced firefighting qualifications” in order to deal with specialist fuels.

The alarm raised by the RMT will add further fuel to the CalMac contract row which has seen the project more than double its budget – while the delivery of both vessels has been delayed.

The two ferries are set to be the first UK-built ships to be fuelled by liquefied natural gas (LNG) and conventional diesel.

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Earlier this month, a Scottish Government adviser told MSPs that state ferry firm Caledonian Maritime Assets Ltd (CMAL) never wanted the type of ferries under construction due to the fuel they will use.

The two vessels will need between four and six road tanker loads of LNG between them each week to run.

Now the RMT union has warned that the use of LNG as part of a duel-fuel design will likely hold up the project even further.

In its written evidence to an inquiry into the fiasco, the union has claimed that the saga could lead to “longer-term effects on crewing in the Scottish ferry industry” and warned that the impact of the controversy on “Scotland’s seafarers and the ferry industry skills base in Scotland is increasingly negative”.

The document added: “Crew working on 801, 802 and future Scottish ferries using LNG and low carbon fuels like hydrogen will need to gain advanced firefighting qualifications, in line with the legal requirements set in the Standards in Training, Certification and Watchkeeping Convention (STCW).

"This will mean longer training periods and the ongoing delay in delivery is making it more likely that CalMac will be unable to properly crew 801 and 802.

“It is important to remember here that crew will have to be in place well in advance of delivery dates, as they are essential to familiarisation work ahead of the formal sea trials and other tests new vessels’ seaworthiness.”

Green politicians said the concerns raised by the RMT should be taken seriously by the Scottish Government.

Scottish Greens transport spokesperson, John Finnie, a Highlands and Islands MSP, said: “The concerns highlighted by RMT show the folly of pressing ahead with an ‘innovative LNG’ design. Ministers should ensure that in future designs are fit for purpose and seek to support efforts to tackle the climate emergency.”

MSPs on the Scottish Parliament’s Rural Economy and Connectivity Committee, which is carrying out the inquiry, have visited the Ferguson Marine yard to speak to workers, engineers and senior managers for their views on the situation.

CalMac’s director of health, safety, quality and environment, Louis de Wolff, said: “The use of LNG places a large responsibility on CalMac to ensure our crews are fully trained and certified in order to operate the new vessels safely.

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“Recruitment of these crews will be done well in advance of the vessels' delivery dates to ensure full familiarisation with them before they enter service.”

A Scottish Government spokesperson said: “We acknowledge and share the frustration of the communities and the workforce impacted by the delays in the delivery of these much needed vessels.

“Our efforts saved Ferguson Marine from closure, rescued more than 300 jobs, ensured that the two vessels under construction will be completed, and secured a future for the yard.

"Our focus will continue to be the people impacted by the delays to delivery of the vessels, including the workforce and the communities patiently awaiting these new vessels.

“We continue to work tirelessly to ensure that the vessels enter service as quickly as possible, to deliver the service improvements upon which our island communities depend.

"A strategy for future work will be crucial to the long-term viability of the yard and we are considering the best approach.

“We continue to work closely with trade union representatives throughout this process – the GMB and Unite unions welcomed the intervention by Scottish Ministers.”