It's a small solution to a big cruise ship problem and it could be a win-win.

An electrical engineer is promoting the cheaper option that will have a minimal impact on the environment when it comes to mooring huge cruise ships like the Ovation of the Seas in Auckland.

The 348m-long, 168,600-tonne ship had to anchor in the harbour on its second visit to the city this week.

Jeremy Penrice believes the best temporary solution to mooring the new generation of mega cruise ships in Auckland is a buoy attached to an anchor in the seabed, similar to what is used for pumping iron sand slurry to bulk carriers off the Taranaki coast and in the oil and gas industry.

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He says the buoy would only be needed a few times a year for the largest cruise ships, could be removed after they leave port and is cheaper than the $10 million to $12 million for a mooring dolphin connected by a walkway off Queens Wharf - the option favoured by Ports of Auckland.

Subsea engineer Gary Teaar, who has advised Penrice and a partner on the project, said the bulk of a cruise ship would be alongside the wharf and the buoy, up to 10m in diameter, would hold the end of the ship beyond the wharf.

An Australian company has also suggested its own solution to Auckland's problem.

MoorMaster's technology uses remote-controlled vacuum pads mounted on wharves and attached to hydraulic arms to moor mega cruise ships.

Sales and operations manager Glynn Jones said KiwiRail introduced the MoorMaster technology for the Interislander ferry Kaitaki 10 years ago after they realised it was longer than the Picton pier.

He said it could easily be used at Queens Wharf at a ballpark cost of $10 million or $16 million for windier conditions.

This diagram shows the Ovation of the Seas tied up to Queens Wharf with a buoy system to the bow from one of two points, depending on the wind direction. Source / Ocel Consultants NZ
This diagram shows the Ovation of the Seas tied up to Queens Wharf with a buoy system to the bow from one of two points, depending on the wind direction. Source / Ocel Consultants NZ

The discussion comes as different arms of Auckland Council and Ports of Auckland scramble for an answer to the problem of cruise ships like the 348m Ovation of the Seas anchoring in the harbour and ferrying passengers ashore.

Cruise New Zealand chief executive Kevin O'Sullivan said something needed to be done - and fairly quickly.

"We just want somewhere to tie the ships up," he said.

The Herald revealed this week that four options are being considered - a mooring dolphin connected by a walkway, a mooring dolphin without a walkway, a dolphin sitting underneath the end of Queens Wharf and a floating or submerged buoy similar to a dolphin.

A council source said the buoy idea was the most logistically difficult, but it appeals to the anti-harbour expansion group, Stop Stealing Our Harbour, which opposes pouring more concrete into the harbour for what is supposed to be a temporary solution.

"The community don't want a massive structure in the middle of the harbour, driving their boats up and down it. The buoy will only be needed three or four times a year," said Penrice.

Ports of Auckland has favoured the connected dolphin option, citing health and safety reasons for a service gangway to allow access.

Mayor Phil Goff asked the council to explore other options after plans last year for a mooring dolphin connected to Queens Wharf by a 3.5m walkway raised fears about pouring more concrete into Waitemata Harbour.

Goff favours making the city's longest wharf, Wynyard Wharf, the main cruise ship terminal once the oil tanks are removed from Wynyard Pt.

The options are due to be presented to council's planning committee next month.