The delivery of two overdue and over-budget CalMac ferries has been delayed again as the shipyard building them struggles to recruit extra staff.
Ferguson Marine hoped to take on 120 extra workers to enable seven-day working but last weekend the new shift had only 29 staff in place.
The nationalised yard confirmed the delivery timetable had slipped by seven weeks due to Covid-related issues.
The difficulties in recruiting skilled workers could lead to a further delay.
Ferguson turnaround director Tim Hair said it was not possible at this time to say with certainty when the ferries would be delivered.
The ferries were originally due to enter service on the Arran and Skye/Outer Hebrides routes in 2018/19.
But the work repeatedly fell behind schedule and costs rose, with the Inverclyde yard's owner Jim McColl and government-owned CMAL, which procures ships for CalMac, blaming each other for the problems.
The Port Glasgow yard went into administration in 2019 with the ferries still far from completion, and was later taken over by the Scottish government.
Under a revised delivery schedule given in August, the first ferry - Glen Sannox - was to be completed between April and June 2022 and the second ship between December 2022 and February 2023.
But in a new update to a Holyrood committee, Mr Hair said recruitment uncertainty meant "it is not therefore possible to provide a definitive schedule for completion of the vessels at this time".
Despite the latest delays Mr Hair said the yard remained "on track" to deliver the ferries within the "remedial work" budget of between £110m and £114m.
How the costs have added up
- £97m - original fixed price contract for design and construction
- £110m-£114m - estimated cost of "remedial work" to finish the ships after the yard was nationalised
- £45m - Scottish government loans to Ferguson prior to its collapse, which are now "written down", an assumption they will not be fully repaid
- £4.3m - "exceptional costs" as a result of two yard shutdowns during the Covid pandemic
Mr Hair said an unforeseen four-week shutdown in January was needed to adapt the yard's facilities to comply with revised Covid regulations.
The lockdowns have also led to a large amount of holiday time being accrued by the workforce, which will add another three weeks to the delivery plans.
In February the yard announced it was recruiting 120 extra staff to enable a move to seven-day working during the spring and summer.
While the weekend shift has now begun, the response has been "limited" with only about a quarter of posts filled. Mr Hair revealed the weekday staffing is also 30 short of requirement.
He said: "Skilled labour is proving very difficult to recruit locally and it seems that the pool of skilled workers available to Ferguson is unable to meet our resource requirements."
The shipyard, which currently employs about 400 workers, is now looking to fill the vacancies through subcontractors.
If necessary Ferguson Marine will look overseas, although the BBC understands there are no firm plans as yet to recruit workers from abroad.