P&O Ferries has reported £15.4m losses in the last year as well as falling passenger numbers.
Dover to Calais ferry services have been disrupted continuously
The company said berthing restrictions at Calais caused it to lose about 20% of Dover-Calais sailings in the first three months of 2005.
But it added that restructuring in its ferries division was on course, with a final 120 Dover job losses when another ship is taken out of service next week.
It is estimated the lost sailings in 2005 will cost more than £5m.
The problems at Calais began on 8 February when a ramp overturned as a lorry was disembarking, damaging a berth.
The company said: "We are now operating close to a full service and the situation should be completely resolved within the next month."
P&O said total passenger numbers on its ferries dropped to 1.5 million in the first quarter from nearly 1.9 million for the same period in 2004.
The losses of more than £5m this year could be offset by cost savings from restructuring, which aims to achieve job cuts of 1,200 across P&O Ferries as a whole.
These were implemented in response to duty-free changes and the growth of low-cost airlines, which created adverse trading conditions.
Despite the challenges in the ferries division, P&O chief executive Robert Woods was upbeat and said: "The trading performance of our main businesses is positive."