Please select your home edition
RS Sailing 2021 - LEADERBOARD

America's Cup Rialto: August 1 - what we've seen in the first week in Auckland

by Richard Gladwell/ 1 Aug 2020 04:28 PDT 30 July 2020
American Magic - Waitemata Harbour - Auckland - America's Cup 36 - July 28, 2020 © Richard Gladwell, / nz

America's Cup Rialto is a new series for the 36th America's Cup, and will publish each day an Americas's Cup boat sails - with images of the day. Usually there will be a morning report (NZT) based on when the boats have passed North Head - when there is usually the best photo opportunity.

Strong winds are lashing the Auckland area, and there was no sailing Friday, Saturday and Sunday.

Monday to Friday of the coming week should be moderate to fresh winds - all from an easterly direction.

American Magic sailed their AC75, Defiant, on three days of the four available, last week. Emirates Team New Zealand, with a choice of an AC75 or a test boat opted to sail only their 12 metre long test boat Te Kahu. We have not yet had the opportunity to see boat AC75's side by side. However we can now go back through previous images in similar locations of the two AC75's and get some idea of their relative strengths and issues.

Te Aihe has a skiff concept complete with a centreline bustle. Defiant is at the other extreme with a scow type hull notable for its shallow underbody, with no bustle. In fact Defiant is now the only AC75 without a bustle - now that the British have retrofitted a similar device within the limitations of the 12.5% hull surface area modification permitted by the AC75 class rule. Luna Rossa launched with a bustle, as did ETNZ's Te Aihe.

Both teams, in Auckland, have perfected the technique of being able to sail to windward with the hulls very close to the water without making contact with the surface. (We presume this is also the case with other teams.) The bow-on view of Defiant is notable for both the low flight height, and what happens when the underside of the hull does appear to make contact with the water. Generally contact appears to be very minimal, causes no spray to be flicked up, unless it is a serious closure with the surface, in which case the displaced water appears to shoot sideways, and gets picked up in the foil spray.

At times, Defiant seems to be throwing a lot of water from her immersed (leeward) foil in winds at the lighter end of the scale. It appears that her ability to foil at the lower end of the wind range is not as good as we have seen on Te Aihe.

Further up the wind scale, there appears to be little difference in this regard between the two AC75's (Te Aihe and Defiant). We can't estimate speed from the shore, and speed guns are not reliable at more than 500metres distant.

In foiling conditions (winds above 7kts) Te Aihe is quick to foil - taking less than a couple of seconds to get foil borne. From what we have seen of Defiant she appears to take five seconds or more to get on her foils, and usually does this by starting very bow up, and with a lot of water being thrown about in the area of the foil arms.

Once she is foil borne Defiant doesn't appear to have too many issues staying in the air, and presents what appears to be a very efficient aerodynamic profile - bow down and slightly heeled to windward. She seems to be able to carry this stance up and downwind.

It is not clear why Defiant appears to be bow-up, when she exits from a tack that is not a dry tack. In the AC75 Class rule the rudder is permitted under control to move fore and aft (rake) and sideways (yaw)

It also must be remembered that in all these images and tests, they are just that - images from test programs. They are not a definitive record of whether one boat will always be slower or faster than the other. Plus one of the test practices is to test a configuration which may be optimal in heavy air, for instance, and would be expected to exhibit some serious downsides in light air. And then of course, as we saw with ETNZ's light air daggerboards in the last Cup, the trick is to extend the range of the preferred board beyond its optimum.

For the 36th America's Cup the competitors are only permitted to use one set of foils per round, which must be declared two days before the start of that round. In the last Cup they could be changed daily - depending on the forecast. As a consequence "All Purpose" wings and flap systems must be used

Of course, Defiant has not sailed for five months and it would be expected that her performance would not be as slick, as had they been sailing solidly (five weeks of lockdown aside) as the Kiwis.

From the amount of time taken during the time outs which have punctuated Defiant's test sessions, our guess is that they have proceeded to try new developments/gear - instead of just sailing the boat in the same design configuration as she was in Florida.

The occasion of Te Aihe and Defiant being on the same patch of water will be of great interest, and the comparison will be continued.

Related Articles

America's Cup: Facilities move to Cork docklands
Irish media are reporting that America's Cup bases are relocating to use publicly owned land at Tivo Irish media are reporting that America's Cup bases are relocating to use publicly owned land at Tivoli Docks, rather than the initial proposal for upgrading a private dockyard in Cobh. Posted on 24 Nov
America's Cup: RNZYS clarifies SGM situation
RNZYS Commodore Aaron Young issues statement around America's Cup venue SGM request Aaron Young, Commodore of the Royal New Zealand Yacht Squadron has issued a statement "to clarify the situation in respect to a member petition for an SGM". The statement text was the basis of an earlier report in Sail-World. Posted on 23 Nov
America's Cup: Blunt talk on NZ Defence Venue
"Need to consider offshore venues. The consequences of not doing so are potentially dire – no Cup" Two motions will be put to the Special General Meeting at Royal NZ Yacht Squadron, whose General Committee, have made the blunt statement "There needs to be a reality check in respect to a New Zealand based AC37 Match...." Posted on 22 Nov
America's Cup: US team continues design work
36th America's Cup challenger American Magic is proceeding with design works and rule analysis American Magic, the U.S. Challenger for the 36th America's Cup [AC36] and a prospective Challenger for the 37th, was pleased to receive the AC37 Protocol and updated AC75 Class Rule Posted on 19 Nov
Dalton, Ainslie and Bernasconi on new AC75 rule
Grant Dalton, Ben Ainslie and Dan Bernasconi discuss the new AC75 Class Rule The third generation of the AC75 foiling monohull will be less complex, lighter, with a little less righting moment, and will foil earlier, than those seen in Auckland in AC36 and the Prada Cup. And the bikes might be back. Posted on 19 Nov
America's Cup: Special General Meeting on Venue
RNZYS Commodore confirms receipt of a request to hold a Special General Meeting on Cup Venue Royal New Zealand Yacht has confirmed receipt of a request to hold a Special General Meeting to consider amending the club rules requiring "…that the America's Cup shall always be defended in the waters adjacent to the City of Auckland" Posted on 19 Nov
America's Cup broadcast wins prestigious award
36th America's Cup presented by Prada wins the ‘Most Successful sports event broadcast' The TV broadcast of the 36th America's Cup presented by Prada has won the ‘Most Successful sports event broadcast' award at the prestigious Sports Business Awards 2021 Posted on 19 Nov
37th America's Cup Protocol announced
With details of AC40 class and mandatory hydrogen powered chase boats The Protocol of the 37th America's Cup was released today by the Defender, the Royal New Zealand Yacht Squadron and Emirates Team New Zealand and the Challenger of Record - Royal Yacht Squadron Ltd and their representative team INEOS Britannia. Posted on 16 Nov
America's Cup: AC75 shortened the AC67.5
The Protocol and revised class rule governing the 37th America's Cup have just been released. The keypoints include reducing the weight of the boat by 900kgs, enable earlier foiling and reduce costs. A major change is in the prohibition of team reconnaissance programs - with all teams having to fund a centralised program. Posted on 16 Nov
America's Cup: Are Irish eyes smiling?
America's Cup: Irish bid to host the 37th America' Cup is further advanced than expected. Email and other documents obtained by two Irish newspapers reveal that the Irish bid to host the 37th America' Cup is still alive and is further advanced than media reports would indicate. Over the weekend a show-stopper for Auckland has emerged. Posted on 16 Nov
Lloyd Stevenson Catalyst 45 728x90px3 BOTTOMSea Sure 2020 - FOOTERCoast Guard Foundation FOOTER 3