Under the plan a 50m vessel would have to pay the council around $1200 per day to anchor in the Hauraki Gulf.
Those berthed already pay fees and would not be affected.
The association's executive director Peter Busfield said yesterday Sardinia had imposed a similar fee and many superyachts stopped going there. It has since dropped the charge.
"It really does look like scalping the superyachts. People think they can afford it but they're people of principle and they don't like to get ripped off."
He estimated 160 superyachts 25m or longer could be attracted for the America's Cup, a high number of which could be caught by the fee because of limited marina space, in spite of new building.
The council was investing close to $100 million on top of the Government's $150m to stage the America's Cup in 2021, with the big spending by superyacht guests and their crew a big part of justifying the public spend, he said.
"Why risk turning away the income we're going to gain as a country that we can make from these people. They spend a lot of money up and down the country from Invercargill to the Far North."
His group accepted there was a need for some form of user pays and suggested a fee of "a couple of thousand dollars" to cover a stay of several months.
He said the area where the fee could be charged stretched from Tiritiri Matangi down past Waiheke to Maraetai and there could be difficulties policing the charges.
"Most have self-positioning systems so don't need your anchor so I don't know if the council will collect any money."
The plan was introduced before Christmas but with submissions to the council closing at the end of the week, opposition is becoming vocal.
But Darby said he had talked to council-owned Auckland Tourism, Events and Economic Development (Ateed) — which is charged with attracting big spenders — and they were comfortable with the plan.
He stressed it wasn't aimed just at superyachts but also cruise ships which didn't come into the harbour but anchored off Waiheke.
Darby, chairman of the council's planning committee, had taken up the cause to impose the levy as he thought it was fair to balance the burden of "mega million dollar value boats" and general ratepayers. "I can understand that those organisations [oppose it]. It's their job to represent that community of interest but I represent a wider community".
The harbour would need more supervision and staff needed more training around the Cup.
Ateed figures say a visit from just one superyacht contributes more than $1m to the economy but in many cases the return can exceed $5m.
This includes expenditure on tourism and hospitality by the owners and crew, and for berths and marine services for yachts.
One superyacht handler, Asia Pacific Superyachts NZ, says it has 16 vessels already waiting to pay deposits on berthing space during the Cup. Darby says council staff would analyse submissions before the finance and performance committee votes on it.
