More doubt has been cast on whether the two ferries being built on the Clyde will ever come into service.
CalMac chief executive Robbie Drummond has warned islanders the next year or two “will be challenging” due to the increasing overall age of the fleet.
Speaking to the BBC on Sunday, CalMac chief executive Robbie Drummond apologised to residents of Arran, most recently hit by disruption to ferry services.
Delays hit the return of Arran's MV Caledonian Isles from its annual overhaul. It has been in dry dock since 9 January. The MV Clansman and MV Hebridean Isles are also out of action due to technical problems.
This has led to delays to routine overhauls of other ferries including the MV Hebrides new covering the temporary Ullapool-Lochmaddy route..
There are now four new ferries being built in a shipyard in Turkey.
But the next ships due to come into service are the MV Glen Sannox and the as-yet-unnamed hull 802, which have faced huge delays and massive cost overruns during construction at the now government-owned Ferguson Marine shipyard in Port Glasgow.
According to the latest official forecasts, the delayed ferries are due to be in service in May of this year and January of 2024, respectively.
But before the new vessels arrive, the ageing fleet is likely to see further disruption, Mr Drummond suggested.
“I’m sorry, again, for the folk in Arran and indeed across our network. We work incredibly hard to bring these ferries back into service, but the next one to two years will be challenging until we see those new vessels coming into play,” he said.
But he assured passengers and islanders that “everyone at CalMac is absolutely focused on delivering the best service we can”.
Reaching to new reports in newspapers that ferries MV Glen Sannox and the as-yet-unnamed hull 802 will never be finished because of arguments over public funding, he said: “If they do not come on stream, then that is a major challenge.”
The boats were originally due to be delivered, six months apart, in 2018
But if the vessels from Ferguson Marine are delivered, Mr Drummond said, that would allow the fleet to have a spare ferry that can be used in case of technical problems or periods of higher demand.
Mr Drummond said a combination of an ageing fleet and having no spare vessels is driving disruption to island communities. He pointed out the ferries serving Arran were now 29 and 39 years old.
“The challenge is simply one of lack of investment. If you go back over the last 10 to 15 years, we’ve not had that level of investment in new ferries coming,” he said.
“On the positive side, that investment is now there.”
Investment decisions are made by the Scottish Government, Transport Scotland, and Caledonian Maritime Assets Management (CMAL).