The amount of time needed to adjust the fenders at the Ferry Terminal in Liverpool has been extended.
An update from the DoI said the request came from the contractors.
In berthing trials for Manxman and Ben-my-Chree last year, it was discovered that, at lower tides, mooring lines clashed with a dolphin fender.
The DoI said: “This means that sailings on November 8 and 9 will be impacted in addition to the sailings on November 1 and 2.
“Once the work has been completed, the berth will be accessible to Manxman at any stage of the tide.”
As a result, these sailings will all operate to and from Heysham, with the Steam Packet putting on a coach transfer for passengers to and from Liverpool.
The DoI has also apologised for any inconvenience caused.