It has 60 vacant rental berths of a size once prized by small keel boat owners.
In a letter to customers, the marina office says the demand for renting 8m and 10m berths, which do not have the convenience of a finger leading from the pier, had decreased significantly over the past year.
"To fill these vacancies, we are adjusting the rental rate to meet the market," said marina manager Kevin Lidgard.
The daily rate of $14 for an 8m non-fingered berth and $16.50 for a 10m non-fingered berth would change from July 1 to $12.50.
The marina, which is in the portfolio of Waterfront Auckland, has 1900 berths or moorings within its 52ha of sheltered water, which makes it the biggest marina in the Southern Hemisphere.
It is undergoing a reconfiguration of the water space to adapt to the trend towards larger vessels and multihull types.
Mr Lidgard said that because of the need for more floating structures, and space for children's sailing boats, 30 swing moorings had to go. It was hoped the lower rental would encourage boaties to move to one of the berths.
"We don't want to lose the people.
"They are paying $8 a day for a swing-mooring and for the price of a cappuccino they could have the convenience of stepping on board from the pier, instead of having to row out."
Mr Lidgard said he believed swing moorings were favoured by seasonal boaties because it was tradition.
"We are confident that we are not denying anybody entry into boating, in fact, the goal is to activate this area - not make it exclusive."
He said the demand for berths with a finger was still strong with a waiting list and a premium of $6 a day over non-finger 10m berths.
The owner of a 8.9m keeler, Dean Graham, said he had considered moving from a rental non-finger berth to a swing mooring elsewhere in Waitemata Harbour but after hearing about the price cut was staying put.
"It's a nice little win, really," said the 40-year-old software developer.
Half of Westhaven Marina's berths are rented out and the rest are occupied by berth licence holders.
Auckland Council member Mike Lee said "Good on them - they are responding to market signals."
• Westhaven Marina is dropping the rental fees by $4 a day for some types of berths.
• From July 1 the daily rate of $14 for an 8m non-fingered berth and $16.50 for a 10m non-fingered berth would change to $12.50 for both.
• It is the biggest marina in the Southern Hemisphere.Auckland Council-owned Westhaven Marina is dropping its rental fees by $4 a day for some types of berths in an effort to win back low-budget boaties.