Team New Zealand's latest boat may look similar to their first, but it's anything but.
"It's a massive change," insists Team NZ head of design Dan Bernasconi. "There's a few similarities to our first boat, but I don't think you can really look at our second boat and say it's an evolution to our first one - it's a completely different kettle of fish."
That could spell bad news for the opposition, who have been scouting the Te Aihe prototype closely.
"We focused particularly on aerodynamics," says Bernasconi. "Most of the time, we'll be foiling, so the aerodynamics are more important than the hydrodynamics."
The most noticeable differences have been made to the hull's shape and size. The bow has a more concave appearance, while the stern's a lot flatter and wider.
They've followed most of the other teams’ lead by making the underside of the hull more pointy, but the challengers will be most interested at how the sails move and are attached to the mast.
"The rig is probably the area where there’s been the most interesting different ideas on how teams have tackled that," says Bernasconi.
The changes will hopefully help the boat go even faster than before, but how fast remains top secret.
"We're keeping the actual top speed of our boat close to our chest," says Bernasconi. "It could be in the region of 10% [improvement] maybe."
Regardless, helmsman Peter Burling has given the changes a ‘thumbs up’.
"Hopefully, a whole heap of things are a lot easier for the users on board, which we're pretty excited about as well," he says.
Burling's job now is preparing the boat and crew for the Christmas regatta, which is only four weeks away. He thinks that’s enough time to catch up to their rivals, who have been in the water for the past few weeks.
"The compromise we make now in the four weeks to the Christmas Cup is gonna be a pretty tight schedule, but it's something we believe will put us in the best shape for the America's Cup," says Burling.
And the best shape to defend sport's oldest prize.
Team NZ have named their boat Te Rehutai, which means 'spirit of the ocean'.
"We looked at following the lineage of the dolphin and the hawk, but we wanted something that took us back a little further to the Waitemata and A-class boats that used to sail on it... just a bit more meaning for Auckland and New Zealand," Team NZ boss Grant Dalton explains to Newshub.
"We're just keen to get it on the water now and see if we reach the numbers we're predicting in the simulator. We'll start finding out tomorrow."