Inter island ferry service in Shetland will be hit by industrial action from today.
Ferry mates, who are members of the Unite union, will refuse to act up as masters and may not work overtime to cover annual and sick leave.
They will also stage short walkouts each Wednesday morning between 6am and 9am starting on December 17 .
The industrial action follows the breakdown of talks between Shetland Islands Council and the trade union over a wage dispute.
The council said the weekly strike was likely to have a “significant impact” as the dates fell on Christmas Eve and New Year’s Eve.
Chairman of the council’s environment and transport committee, councillor Michael Stout, said: “It is extremely disappointing that we find ourselves in this position, as we have done everything we possibly can to resolve the situation.”
The dispute relates to a job evaluation around two years ago, which originally would have given the affected staff a pay increase.
But, following a reassessment during single status pay negotiations, they were put down a salary grade.
Mr Stout said the council had a legal duty to pay equal pay for equal work under the single status agreement, and could not break that agreement by re-grading individual staff groups on demand.
“I appreciate that mates on our ferries feel that they were treated unfairly under the single status collective agreement by not receiving a pay rise.
“Very early on it was mooted that mates could be re-graded at a higher rate, but that wasn’t the eventual outcome, and that was upheld at appeal and at a later re-evaluation.
“It is clear that these employees receive the correct level of pay for the work they do.
“We have done everything we can to recognise the goodwill shown by mates who are called upon to act up as masters, and indeed pay them accordingly, but we simply cannot make an increased pay award to a single group of staff,” he said.
Both sides have now agreed to go to the mediation service ACAS in a bid to resolve the dispute, but this will not happen before the industrial action begins.