CalMac workers have confirmed that they will begin industrial action this week, after talks between unions and the ferry operator broke down.
Members of the Rail and Maritime Transport (RMT) union will stage a 24 hour strike on Friday over concerns about jobs, conditions and pensions.
The strike will be preceded by two days of work to rule, with a ban on overtime.
The RMT said that talks today with CalMac had failed to “make significant progress”.
The union have also raised concern about a bid from private operator Serco to take control of the Clyde and Hebrides franchise from publicly owned CalMac.
The RMT say they are available for further talks as the strike action begins.
General secretary Mick Cash said: “The talks with CalMac have not made significant progress despite the best efforts of our negotiators and as a result the action goes ahead from Wednesday.
“It is extraordinary that rather than standing up for Scotland’s lifeline ferry services those who hold political power have resorted to ludicrous arguments about what does and doesn’t represent privatisation. That is a kick in the teeth for loyal and hard working staff who have given long hard years of service at CalMac.
“RMT members on CalMac rightly feel that they are caught in the crossfire of an unnecessary and damaging tendering battle that leaves jobs, conditions and pensions hanging by a thread. That is simply intolerable.
“RMT wants cast iron assurances and we want them now and we are committed to engaging in meaningful talks around that agenda as we kick off the first phase of industrial action.”
CalMac have been contacted for comment.