The MV Clansman ferry, which has been dogged by repair issues recently, will be going into dry dock again in June for a new propeller shaft to be fitted.
The ferry had a temporary repair to its propulsion system in order that it could remain in service, but now the permanent replacement part will be be fitted.
The vessel will be in dry dock from June 1st and it is expected to return to service on June 12th.
However the absence of the ferry during this 11-day period will mean the Mallaig to Lochboisdale route will be suspended and an amended service will operate on the Mallaig to Armadale route.
Customers wishing to travel on the Mallaig-Lochboisdale service will be directed via Oban to Castlebay and Uig to Lochmaddy.
Additional sailings have been organised on the Barra to Eriskay route enabling passengers to travel to South Uist via Oban to Castlebay on the same day.
The MV Loch Bhrusda will also be deployed on the Skye route to provide additional sailings for the duration of the maintenance period.
CalMac, managing director, Robbie Drummond, said: “This is an essential piece of work that we wanted to schedule in before the summer season fully started and have built a temporary timetable that causes the least disruption whilst maintaining all lifeline services.
“We fully appreciate the impact this will have on the communities affected which we apologise for.
“In the circumstances we have tried to limit the disruption to as few routes as possible and will deliver extra sailings to help manage passenger movements as best we can within the resources we have available.
“Although it will be frustrating for communities to see the Clansman come back into service and then leave again so soon, this was a preferable option to having her laid up until the new propeller shaft was manufactured, delivered and fitted.”
A full scheduled timetable is expected to run again from June 13th.