The overnight Manxman sailing from Heysham has been delayed until 3:30am.
She had been due to sail at 1:45am, but was twice delayed.
Having initially told passengers to expect a 2:15am, this was then pushed back again to 3:30am.
At current, the 8am sailing is scheduled to depart at 7:30am. However, this would appear unlikely.
The company has asked passengers to check in no later than 06:45am.
The later sailing from Heysham to Douglas, originally due to leave at 1:45pm, was due to be brought forward to 12:45pm.
However, a final decision that sailing is due by 6am Thursday morning.