After winning their sixth World Championship in the Olympic 49er class on Saturday, reigning America's Cup and Olympic champions, Peter Burling and Blair Tuke were back on the Waitematā on Tuesday.
Burling swapped the tiller extension and trapeze of the 49er for the crash helmet and steering wheel of Emirates Team New Zealand's 38ft test boat. The five-hour test session was sailed in a 10-12kt sea breeze - giving Te Kāhu and its four crew a good workout.
The half-size AC75 is the real deal, maybe a little slower upwind, but downwind it flies. Stringing together the dry tacks and gybes didn't seem to be an issue for Burling and co.
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Team NZ CEO, Grant Dalton says Te Kāhu is a "cool boat, brilliant tool and we have some seriously cool developments coming on stream over the next six months. Time will tell, but I think we have this around the right way".
That last comment is a reference to the fact that Team NZ is an outlier in the way it has run its program for the 2021 America's Cup.
All the challengers launched prototypes or test boats ahead of their first AC75, the foiling monohull keelboat to be used in the 36th America's Cup. Some were more successful than others - New York Yacht Club's American Magic would now seem to be the only team with a viable test boat.
With TNZ's AC75 Te Aihe heading for Europe to compete in two America's Cup World Series events in late April and early June, the smaller Te Kāhu will do much of the heavy lifting for their design team over the next six months.
Exercising the minds of all design teams will be the requirement in the newly released match conditions, requiring teams to present their boats in a set measurement configuration before the start of each Prada Cup or America's Cup series.
That puts an end to the moding that has been a regular part of the America's Cup - dating back to 1983 and the 12-metre class where Dennis Conner had multiple measurement certificates for the red-hulled Liberty. His idea was to optimise the boat for each race based on the weather forecast - even so they still lost to Australia II.
This concept was carried into wingsailed catamarans used in the 2017 America's Cup in Bermuda. The teams used two sets of daggerboards - one set to provide high lift and promote foiling in the light weather. The second smaller set was an All-Purpose (AP) set that was used in stronger winds - providing the required lift, but also less drag equating to faster speed.
Foiling is a concept to changing gears in a car - you need to start in first gear to get moving, and then change up to a more efficient gear to travel at speed.
For Auckland, only one set of boards will be permitted which will have to work across the 6.5kt to 23kt wind range of the America's Cup match. Wing flaps, similar to those on an aircraft, are now permitted.
Team NZ is again the outlier with a set of wings that span the full 4 metres permitted. The other teams have opted for stubbier wings, which in theory add less drag. But that gain is offset with the addition of a drag increasing ballast bulb to bring the wings up to the permitted maximum weight of 971kgs.
It will be intriguing to see whether the challenger teams continue to have the design courage to take a different direction in both hull shape and wing design, from the America's Cup champion.
Another area in which Team NZ is the outlier is in their buildup for the America's Cup. The home team is the only one sailing in the Cup venue, in the same time frame a year out from the match.
The Waitematā Harbour, offering spectator-friendly racecourses, will be very different from those used for previous America's Cups. Sandspits, reefs and lighthouses punctuate the course area, making it more akin to a golf course than a yacht race. The trick for the skippers will be to find the twisting fairway and stay out of the bunkers and rough.
The decision on which area to race will now be left to newly-appointed race director, Iain Murray, who oversaw the last two America's Cups in San Francisco and Bermuda.
The Priority 1 course for the racing flanked by North Head and Bastion Point holds a special significance for Murray - in the final race of the 1977 18ft skiff World Championship, Murray (then an 18-year-old student who dabbled in boat design) ordered the spinnaker up on the torrid last leg.
Murray's crew was the only one to attempt the feat in a 25-35kts near-gale. The daring move paid off - Murray came from behind to add the 18ft-title to the Interdominion 12ft-title he won in the same waters 12 months previously.
Over 40 years on, it will be interesting to see how Murray treats claims from America's Cup crews that it is "blowing too hard" for racing.