Arran's new ferry won't arrive until late May (at least)

Delays in specialist pipework being carried out means the LNG gas system on the dual-fuel ferry won't be fully commissioned by the latest deadline.

CalMac will then have to conduct weeks of sea trials before the ship enters service.

The Ferguson Marine shipyard has now put back the launch of the second new Arran ferry MV Glen Rosa by four weeks to focus on Glen Sannox.

Both ferries being built at Port Glasgow were originally due for delivery in 2018 but have been beset by repeated design and construction problems.

The ships, which can use both LNG (liquefied natural gas) and conventional marine diesel, are the first LNG-powered vessels ever built in the UK.

The gas fuel must be kept at temperatures between minus 160C and minus 170C under high pressure, and requires specialist "cryo steels" for the pipework.

In an letter to MSPs, Ferguson Marine said this pipework should have been delivered last year, but was delayed and the yard had to engage an alternative UK company which arrived on site in January.

Installation should now be finished by mid-March but the supplier will have to begin 10 weeks of commissioning and testing for the gas systems.

The yard hoped to deliver Glen Sannox by the end of March but Ferguson Marine chief executive David Tydeman said late May was now the planned date and warned of possible further delays and costs.

He wrote to Holyrood's Net Zero, Energy and Transport committee: "We are evaluating the risks to further slippage on the planned late May handover date for Glen Sannox, the cascade impacts onto Hull 802 (The Glen Rosa) and the overall costs to complete impacts for both ships."

Mr Tydeman said he would give MSPs a further update before they visit the shipyard later this month

The shipyard's launch of the Glen Rosa, due  on March 12 has now been put back to April 9.