Problem with the stern tube bearings
Work on the Ben-my-Chree has been delayed with the vessel not expected to return to service until the end of May.
Inspections, whilst the boat has been in dry dock, have identified that specialist third party work is needed to repair the stern tube bearings.
The Steam Packet has confirmed Manannan will continue to operate daytime passenger services and the MV Arrow will provide overnight freight services.
Chief executive Mark Woodward says: "It is important we use this quieter period to comprehensively attend to this unexpected issue.
"The travel restrictions still in place due to COVID-19 helps ensure that progressing this now will cause minimum disruption.
"Once the full testing of control systems, equipment and safety checks are completed, we look forward to welcoming her back, fully serviced and ready for, hopefully, a busy season."
Passengers who are affected by the change will be contacted.