Harbour charges in Falmouth are to increase to cover a deficit in pensions for the port's pilots.
Falmouth Harbour Commissioners (FHC) has been told it will be expected to re-pay around £3 million over the next ten years to the Pilots National Pension Fund (PNPF)
And it has defended its decision to raise charges for commercial shipping to help offset that contribution.
A High Court ruling in 2010 means the Trustee of the fund has the power to demand contributions form the Competent Harbour Authorities across the UK that have employed or authorised pilots to cover a deficit of almost £200 million.
Captain Mark Sansom, chief executive of FHC, said: "Increasing charges is not something we have done lightly, but we feel we had no choice but to take immediate action.
We've known for some time that there would be deficit recovery plan, but it is only recently that we have learned what our contribution is expected to be.
"Our view is that this issue is not of our making and in common with many other ports and harbours have written to the Trustee urging them to adopt a longer repayment time.
"However, whether this is successful or not, it is not clear and that an increase in harbour charges will be necessary to help fund the deficit repayments. We have therefore written to our commercial shipping customers to inform them of increases in charges which will take effect from January 1.
"We will be re-evaluating all our business plans in light of the deficit repayments."