Patriot has a deceptively complex and changing hull shape. Photo / Richard Gladwell
Two of the AC75 race-boats to be sailed in the 2021 America's Cup regattas have now been launched in Auckland, with a third to follow on Tuesday.
Patriot, the US challenger representing the New York Yacht Club, was launched at 9.00 am on Friday from the team base on the new Wynyard Marina.
American Magic's second AC75 is a substantially different design from the team's first launched, Defiant - which first sailed over a year ago.
As expected, Patriot has fallen into the same skiff-design genre as Luna Rossa and Emirates Team New Zealand's first-launched AC75's.
The key features are a flared bow - which is very unusual on a yacht and will give this AC75 plenty of buoyancy in the bow to prevent a serious nosedive.
That design feature got its first test on the maiden sail a few hours after Patriot's launch when the 7500kg AC75 did a spectacular jump clear of the Waitemata, before diving in bow-first. The flared bow paid its expected dividend, popping Patriot back out of the violent re-entry, and it could have continued the training session, but for a couple of hydraulic oil leaks.
Like the Kiwi, Italian and British first-generation AC75's, Patriot carries a skeg down the centre of the hull, but one which is much smaller than those used by the Italians and New Zealanders. It runs the full length of the underbody of the hull but becomes less prominent towards the stern.
Above the waterline, there are significant differences. The open cockpit of Defiant has been replaced with trenches running down each side, from the mast back to just short of the stern.
These are similar to the trenches featured on Emirates Team NZ's Te Aihe, but much better defined and appear to be deeper with the crew working well down in the hull of the boat, rather than being on a deck or cockpit.
The crew will be well protected and with their bodies low enough in the boat to reduce windage and speed-robbing drag.
But by having the afterguard, of the helmsman, trimmers and flight/foil controller deep in the boat makes it less easy to switch sides as the boat tacks or gybes. Emirates Team New Zealand has made a similar trade-off. Before and after tacks or gybes three of the crew take their turn to switch sides, requiring a nimble and very finely judged run around the back of the mainsail.
There is a wide running track on the aft deck of Patriot, covered with non-skid. But not a lot of handholds on the AC75 which should be foiling at speeds of 50kts or more.
Patriot's foredeck tapers from a high point around the mast down to the bow - which forms an endplate between the foot of the jib and the mainsail. Sealing the gap between sail and deckline tidies up the airflows and makes the rig more efficient.
The sloping deck also provides good protection for the crew who have two sets of winch grinding stations, ahead of the helmsman, in each of the side trenches.
The second to launch, INEOS Team UK's Britannia was splashed early on Saturday morning before stepping her mast later in the day. They too have dropped the scow-genre hull form of their first AC75, and have opted for a skiff style design form.
Like their first launched, the Brits' AC75 is an extreme design. Britannia features a stepped chine which allows a narrow, low drag in the water shape, but kicks in with a massive amount of additional buoyancy in the event of a splashdown.
The bow and forefoot of the hull also features a high volume skeg, but instead of being rounded, or v-shaped like the other AC75's, Britannia's has a large flat area on the bottom of the skeg.
The back end of the British boat is more conventional, with the crew being housed in trenches in a very similar style to American Magic's Patriot, and with the helm position behind the winch grinders.
The three Challengers flew their hulls into Auckland earlier in October in three separate visits by an Antonov 124. The air-freight option was necessary to comply with the America's Cup Protocol rules which require that the hull of the AC75 be constructed in the country of the challenging yacht club.
Flying the hulls into Auckland, at an indicative cost of NZD$1.5m, gave the team designers an extra five or six weeks on the programs - compressed, or certainly affected by the COVID-19 pandemic and various measures adopted in UK, Italy and USA.
Once offloaded in Auckland, the white shrink-wrapped and heavily disguised hulls were taken into the team bases in the America's Cup Village for commissioning, and launch.
The second-generation AC75's were expected to be a big step up from the first launched boats, which were splashed around 12 months ago. The final hull designs for the second generation AC75's, now being launched in Auckland were all signed off ten months ago - necessary to meet tight construction deadlines.
The four AC75's produced in the first round of designs were all quite different, as is usual in the initial rendition of a one America's Cup Class rule. Surprisingly, Patriot and Britannia have not fallen closer to one of the existing boats. Six very different AC75's have now been launched.
Of the last three America's Cup Class rules, the AC75 class rule is the most open allowing maximum design latitude, creativity and innovation.
"The AC72 rule used in San Francisco was semi-open," explains Emirates Team New Zealand's design chief Dan Bernasconi, one of the team who spent six months developing the AC75 rule.
"In Bermuda, the AC50 rule was very restrictive hull shapes were one-design, the sails were one design, there were very tight rules around the foils.
"This time we have made the playing field really open. There are two reasons for that. It is just cool with a new class of boat to allow it to be open and to allow the boats to develop, with three years of design and optimisation.
"The other reason is that we believe in ourselves and our ability to simulate what can work well - so we feel we are a strong team when the design rules are open."
Italian challenger, Luna Rossa launches their AC75 on Tuesday, with Emirates Team New Zealand to follow in early November.
At the end of that cycle, the key point of interest will be whether the second-generation AC75s continue to be as divergent as their first launched designs.
One thing is for sure - they can't all be right.
Luna Rossa have been active in their recruitment drive for the next America's Cup.