Team New Zealand grinders were seen sitting upright, enabling them to let their legs do the work, instead of using conventional grinding pedestals.

Team New Zealand have tested their America's Cup boat in Auckland ahead of Thursday's official launch and revealed cycle pedestals for their grinders using leg power.

The new 50-foot catamaran carries New Zealand's hopes of regaining the America's Cup when the regatta is held in Bermuda in May and June.

Team New Zealand, who pioneered foiling at the last edition of the cup in 2013, have again pushed the boundaries.

RICHARD GLADWELL / PHOTOSPORT Traditional grinder pedestals were missing from the desk of the new 50-foot catamaran.

The move away from the traditional arm work of the grinders to the more powerful option of leg work will be monitored closely by rivals.

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RICHARD GLADWELL / PHOTOSPORT An opposition spy boat kept Team New Zealand under close observation.

There was an opposition spy boat on the Auckland harbour on Tuesday as skipper Glenn Ashby and his crew took the AC50 for a quick blast, according to a report on Sail-World.com by well-connected Kiwi yachting writer Richard Gladwell.

The sail was reportedly impressive in misty conditions with the catamaran lifting on her foils in just 4-6 knots of wind.

The boat reportedly featured four grinding pedestals on each hull. The grinders have to provide hydraulic power fr the massive wingsail and the leg power is expected to be less taxing on the crew.

REUTERS Skipper Glenn Ashby will be hoping he's still smiling at the end of the America's Cup as his Team New Zealand syndicate opts for a radical design change for the 35th edition of the famous regatta.

The other five syndicates are expected to go with conventional grinding methods to provide the power for the ultra-fast boats.

The question now is how they evaluate the Team New Zealand development and whether they have time to emulate it.

Rival syndicates played a quick game of catchup in the foiling department in San Francisco with Oracle eventually out-playing Team New Zealand at their own game.

Ben Ainslie Racing (Britain) is the only syndicate to have launched their 2017 racing catamaran so far.

Cup holders Oracle Team USA are expected to launch their latest design in Bermuda on Wednesday (NZ time).

Team New Zealand are expected to do the bulk of their testing and training on their new boat in Auckland before transporting it to Bermuda.

They will use that travel time as their 28-day sailing "Blackout", a recent change to the Cup protocol enforced on teams in the leadup to Bermuda racing.

Team New Zealand have started building their base in Bermuda while retaining a reduced operation in Auckland to cover off their final spell in New Zealand ahead of the Louis Vuitton qualifying series which starts on May 26.