The new Glen Sannox ferry is expected to resume sailings on Sunday afternoon following repairs to a hairline crack in the ship’s hull.
But CalMac confirmed the scheduled morning sailing had been cancelled to allow a second test on the welding work.
The repair was completed on Saturday, following an assessment by divers, but will undergo a fresh examination once it has cooled off.
The brand new vessel only began operating in January after being delivered almost seven years late and costing more than four times the original contract price.
CalMacThe ferry had been operating for just over two months between Troon in South Ayrshire and Brodick in the Isle of Arran.
On Saturday evening CalMac announced repairs to the crack on a weld seam on had been completed.
And it said if fresh tests are successful the Glen Sannox will resume service at 14:50 from Brodick.
A spokesperson added: “This means the first morning return sailing is cancelled, but all booked customers can be accommodated on other sailings with space available.
“The 12:40 MV Alfred was due to operate from Brodick will be brought forward to 11:20.
“We are grateful to the vessel’s crew, our local port staff, plus the dive and repair teams for their speedy response to this issue.”
The MV Alfred operated an extra return sailing on Saturday to provide cover and the operator said the “vast majority” of booked customers had been able to travel.
The vessel was removed from service on Friday after a crack was found on a “weld seam close to the waterline”.
The ferry operator said reports that the boat had hit the harbour or that water was leaking into the car deck were “categorically untrue”.
However, CalMac advised that a “very small amount of water” had entered part of the rear of the ship near the steering gear.
Passengers earlier expressed frustration over the postponement of Saturday sailings on the Glen Sannox, which has space for 127 cars and 852 passengers.
Ewan Thomson, who has a home on Arran, had to carry tools he was using for renovation work as a foot passenger as he was unable to book his van on the journey back to the mainland.
He told BBC Scotland News: “The Scottish government have pledged money to Ferguson Marine for the best of reasons but who in the world would buy a boat from them?
“I would not buy a rowing boat from them.
“They can’t deliver on time, they can’t deliver on budget and they can’t deliver a boat that sails on the water.”
Diana Turbett has lived on the island for 37 years.
She said: “I have never known such uncertainty and the fact there is a crack on a brand new boat is concerning.
“I have seen people raise concerns about the quality of the welding.
“It is very worrying.”
The order for Glen Sannox and another ship were placed with the Ferguson shipyard in Port Glasgow nearly a decade ago.
But disputes over the design and claims for extra costs saw the shipyard fall into administration, and then be nationalised in 2019.
The ships have ended up costing more than four times the £97m contract price.
A Scottish government agency owns the ferries, leading to criticism of the SNP from opposition parties.
Scottish Conservative West Scotland MSP Jamie Greene said: “This latest fault has marked yet another unforgivable chapter in this shambolic ferry fiasco.
“While it’s welcome that services are to resume on Sunday, passengers will wonder why problems arose with the Glen Sannox just weeks into launching after a seven-year delay.”
And Scottish Liberal Democrat MSP Willie Rennie said: “This has been a never-ending nightmare for this SNP commissioned ferry contract.”
