The Steam Packet's fast-craft is operating on reduced power because of a technical issue with one of its engines.
Crossing times will be up to 45 minutes longer than originally scheduled depending on tidal conditions.
A spokesperson from the ferry operator said: ‘Isle of Man Steam Packet Company vessel Manannan is operating on reduced power after suffering a technical issue with one engine.
'The issue is currently under investigation by engineers.
'The cause has not yet been conclusively identified.
'Passengers are reminded of the importance of checking in for sailings no later than advised to help ensure potential delays are kept to a minimum.’