Boaties were warned of the likely location, but that was too late for Peter Henriksen, of Hamilton. He was motoring up the harbour on his 11.28m launch after a few days on Waiheke with his wife when he hit the Gypsy's sunken wreck about 200m off the Hilton wharf.
He said there was a "big bang" and the back lurched forward.
"We had hit something quite solid and it turned out to be the mast of the Gypsy," he told the Weekend Herald.
"We'd actually smashed the mast-head lights off the top of [the wreck] and they floated to the surface."
He alerted the harbourmaster, who said the process of determining whether the Gypsy was a navigational hazard was under way.
Harbourmaster Andrew Hayton said that once his office was notified of the incident, it sent out a Notice to Mariners and informed the contractor searching for the wreck.
"The contractor dragged for the wreck in the new reported position, but only located a log on the seabed."
Mr Hayton said that one of his patrol boats then recovered "a quantity of floating debris".
"Until yesterday [Thursday], the harbourmaster's office did not consider the sunken vessel to be a hazard to navigation due [to] the depth of water, the type of vessel, and the intelligence on hand as to the nature of the damage that she had sustained prior to her sinking."
Mr Henriksen said the harbourmaster did not act fast enough and failed to signal to boaties where the wreckage was.
"They could have at least put buoys around it, but there wasn't even that."
Mr Hayton said the contractor had been trying to find the wreck since the collision, but because it kept moving, it was not possible to mark exactly where it was.
"The wreck has been moving on the seabed due to tidal streams and currents, making the job of trying to locate it difficult."
The Ports of Auckland survey vessel spent several hours yesterday searching with sonar, and finally found the Gypsy.
"Neither the harbourmaster's office nor Auckland Council takes any responsibility for damage done to other vessels.
"This incident is a timely reminder of the importance of maintaining a proper lookout at all times and of the need for all vessels to follow the Collision Prevention regulations," Mr Hayton said.
Mr Henriksen said he had not received a quote for the damage - which includes a "smashed" propeller - but estimated it would be $6000 to $8000.
He said his boat was insured, but the $1000 excess would have to come out of his own pocket.