The Department of Infrastructure says it'll increase charges for berthed boats by more than 19 per cent this year.
When Tynwald sits on Tuesday, members will be asked to increase harbour dues under new regulations.
The DOI says some pleasure craft are being berthed against harbour walls and abandoned, and ageing port infrastructure is in urgent need of investment.
As a result, it says it'll put those harbour dues up by 19.26 per cent, with further increases planned in the next three years.
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