It is reported the ship was stuck between Greenock and Helensburgh for several hours.
It later made it to Greenock and owners Waverley Excursons Ltd apologised for the inconvenience to passengers. It said it was due to a problem with the boiler controls.
The Waverley had set off from the centre of Glasgow at 10am on Saturday, and it was due to stop in Helensburgh, Dunoon and Rothesay.