Harbourmaster Jim Lyle said problems with the vessel included a broken generator, oil in the fish holds, and basic safety equipment that was not functioning.
It would have to be slipped in Whangarei to get the faults rectified and its commercial licence renewed, but it would have to pass a survey before it was allowed to leave Mangonui. With surveyors busy at this time of year that could pose a problem for the owners, Mr Lyle said.
"We can't allow the vessel out to sea in the state it's in at the moment. There's so many things not working."
The lesson was that owners had to keep their vessels shipshape and properly maintained or they would not be allowed to operate off the Northland coast.
According to the Ministry for Primary Industries, the William R is registered to Tauranga-based RMD Marine.
Director Marcus Rawlinson is out of the country and could not be contacted for comment yesterday.
The vessel, currently in use as an eeling boat, was still tied up alongside the wharf yesterday. It is thought to have been built in Whangarei in 1974.