Ferry operator CalMac has started its winter maintenance programme.
Over the coming weeks, ships will be taken off their regular routes for a series of inspections, upgrades and maintenance.
Services for various islands will experience temporary changes as the fleet is rejigged to provide cover.
Two relief vessels will operate sailings on the Stornoway-Ullapool route as the MV Loch Seaforth goes off to dry dock on the Mersey for three weeks.
MV Isle of Lewis has left her Barra run to cover the Stornoway daytime timetable.
MV Isle of Arran has completed her own drydocking and will cover the Castlebay-Oban run.
Stornoway freight services will be provided by the Islay ferry, MV Hebridean Isles, which will undertake two daily return crossings of the Minch.
Travelling times will take longer on both routes due to the slower speed of the replacement vessels.
In early November, the Hebridean Isles will head off for her own dry-docking, meaning services for Islay will be reduced to a single ferry timetable until the middle of next month with MV Finlaggan operating the Kennacraig-Port Askaig route.