A boat owner from Finedon was among nine ordered to pay more than £9,000 after being prosecuted as part of an Environment Agency clampdown last month.
Two more were sentenced at Northampton Magistrates Court after their unregistered vessels were found on the River Nene at Oundle Marina.
David Campion of Oxford Street, Finedon, was ordered to pay £1,204.24 after his vessel Dancing Foam was found unregistered at Buckden Marina on the River Great Ouse.
Mr Campion was fined £400 and ordered to pay £579.24 in costs and compensation after the case was proved in his absence at Cambridge Magistrates on January 16.
Meanwhile, Martin Jewkes of Aspley Way, Peterborough was ordered to pay a total of £767 and Suzanna Sutton, of West Street, Peterborough, faced a £1,153 punishment after pleading guilty by post at Northampton Magistrates on January 27.
Mr Jewkes was fined £123 plus costs and compensation of £644.51 for his unregistered vessel Domino. Ms Sutton was fined £460 with costs and compensation of £693.51.
Six other offenders were ordered to pay between £330 and £1,562.46 in hearings at Northampton, Luton and Cambridge for offences on the Nene, Great Ouse and Old West rivers,
Boat owners are legally required to register any vessel they keep, use, or let for hire on Environment Agency waterways and to clearly display a valid registration plate.
And the Environment Agency, looks after 353 miles of navigable waterways in the Anglian network, warns boaters who fail to comply face thousands of pounds in penalties, a criminal record and even have their boats confiscated.
The money from court action – as well as the properly paid registration charges – is reinvested back into Anglian waterways to protect, maintain and improve them for everyone.
Nathan Arnold, Waterways team leader at the Environment Agency, said: “Our waterways are part of our nation’s rich heritage and beauty, and they contribute to our environment, our health and wellbeing, and our economy.
“But boaters who break the law by not registering their boats are putting the future of these historic and precious waterways at risk – so we won’t hesitate to take action against them.”
As well as not contributing their fair share towards the upkeep of waterways, unregistered boats can be unsafe, hazardous to other river users and a pollution risk to the local environment and wildlife.