Ferry operator Cal Mac is aiming to work to a 90% complete timetable in the face of industrial action from the RMT union on Wednesday and Thursday this week.
Temporary timetables are now in place and passengers should check them before travelling.
Cal Mac's managing director, Martin Dorchester, said: “We are disappointed that our dialogue with the RMT to avert industrial action this week has broken down but we now have in place plans to protect the vast majority of sailings tomorrow and Thursday.”
“The RMT are refusing to work overtime for the next two days potentially causing huge disruption to our services.
"Our staff have worked flat out to try and mitigate this industrial action as much as possible.”
"The temporary published timetables are subject to change so travellers should double check before setting off.
“We have made several serious concessions to the RMT including a commitment on no compulsory redundancies in our bid submission in return for the RMT calling off the industrial action planned for this week.
"Unfortunately this was rejected. We were also willing to work together with both the RMT and TSSA over the coming days to agree a form of words in our collective agreements which would provide greater protection to employees around terms and conditions of employment but without success.”
The company warning people still face serious disruption when full RMT strike action on Friday.
Passengers urged to double check ferry times during union action
23 June 2015