SCOTLAND'S lifeline ferry network faces longer disruption running into the Spring bank holiday weekend after it emerged plans to have its largest vessel back in service have been put off for a sixth time.

MV Loch Seaforth was taken off the Ullapool-Stornoway route by state ferry operator CalMac a month ago to be taken into dry dock for "major" engine repairs.

The publicly funded firm had initially said the eight-year-old vessel would out of action until "at least the end of April" at the earliest but has since kept putting that date back.

After a series of schedule changes, ten days ago, CalMac said it was expected back by May 28 at the earliest.

Now as the islands start to open up to visitors with the easing of Covid-19 restrictions, the return of the vessel has been pushed back yet again to May 31 at the earliest.

READ MORE: CalMac ferry network crisis as breakdowns cause three day island freight shutdown

CalMac say specialist engineers are currently rebuilding the six-year-old vessel's engine and that she should be able to leave wet dock in Greenock on May 28, once successful testing has been carried out.

The Herald:

The vessel will then undergo the required 50-hour period of sea trials whilst in transit to Stornoway.

Following the initial repair to the Loch Seaforth engine, damage to the crankshaft was identified during post-repair testing that required further action.

CalMac say crankshaft bearings have now been disassembled and inspected and the damaged bearing has been replaced.

Related damage has been repaired by polishing. The sump and oil system has also been cleaned and inspected.

CalMac said that "intrusive inspections have been conducted and no further damage has been found".

The Herald revealed how the failure of Loch Seaforth resulted in cuts to other services across the ferry network as vessels relied on with other routes were shifted around to accommodate.

Campaigners had described the situation as a "national scandal" and that those responsible should already have lost their jobs for the state of Scotland's ferries.

It meant that the temporary shifting of ferries to cover for Loch Seaforth's loss will remain in place. That means MV Isle of Lewis, which was taken off its usual route between Castlebay on the Isle of Barra and Oban in Argyle to support the Loch Seaforth run will remain.

One of Scotland's busiest ferry services, the Ardrossan to Arran route, will continue to remain serviced by one vessel, rather than two.

According to the Arran Recovery Group, the shifting of the ferry for the start of the summer tourist season will cost the island more than £500,000 in lost business.

The 38-year-old MV Isle of Arran - which normally runs on the Ardrossan to Arran route - and was taken off freight service duties on the Ullapool-Stornoway crossing because of stabiliser problems, resulting in a shutdown on services for over three days, has been operating on the "more sheltered" Islay run.

There was criticism when it emerged that as Isle of Arran only had space for four lorries.

The 36-year-old MV Hebridean Isles, ended up replacing the Isle of Arran on the Stornoway crossing on Saturday causing cancellations on its usual Kennacraig to Islay.

If the Loch Seaforth returns to action, the Isle of Arran will return to the Brodick-Ardrossan route allowing a return to the two vessel service on June 3.

On arrival at Stornoway, the Loch Seaforth will undertake further inspection to ensure that no further issues have arisen from the sea trials, said CalMac.

Until the Loch Seaforth is back in service, existing temporary arrangements and timetables will remain in place, including the replacement freight service on Stornoway-Ullapool and the temporary timetable on Ardrossan-Brodick.

Robbie Drummond, Managing Director of CalMac, said: “Specialists are working throughout the day and night on the MV Loch Seaforth to ensure her safe return to Stornoway-Ullapool.

“This has been an extremely frustrating time for passengers and our staff and I am grateful to them all for their continued patience.”

The latest issues come off the back of the country's ferry building fiasco at the now state-owned Ferguson Marine The two lifeline ferries being built at Ferguson Marine which were due to be in service in early 2018 are now up to nearly five years behind schedule and their cost is now over double the original £97m contract.