Cup Spy Oct 5: Making the dog hunt
by Richard Gladwell/Sail-World NZ 5 Oct 2023 20:02 PDT
6 October 2023
Emirates Team New Zealand - AC75 - Day 44 - Barcelona - October 5, 2023 © Ugo Fonolla / America's Cup
Three teams sailed off Barcelona in moderate winds on Thursday.
Barcelona turned on another weather variant on Thursday, with a moderate breeze initially of 8-12kts at 1300hrs, increasing to 13-15kts at 1700hrs - as measured ashore by the nowcasting at Port Olimpic.
Rather than being steady from the South as it has been on most days, the breeze started at NE (045 degrees) at 1200hrs, swinging slowly to ESE (100 degrees) at 1600hrs - followed by a rapid and significant shift to the South (180 degrees) 30 minutes later at 1630hrs.
According to the reports from the AC37 Joint Recon Team, and especially those following American Magic sailing paired AC40s in yet more foil testing, the wind was unstable, making accurate testing unreliable.
It is important to recall American Magic's Tom Burnham's comments earlier in the week, when reading any observation report, that often what is perceived as one boat being faster or slower can be part of an alignment process between the two boats - checking that a line up is an accurate and fair test and that one boat is not affected by the other, or by inconsistency in conditions.
Having watched a lot of one and two-boat sailing over the past 30 years, it is only when you are linked into the on-board communication systems between the chase boat, the shore test base, and the sailing boats in the test, that you know if an objective test is underway, or if it is just an alignment/calibration.
Only the teams know when serious testing is underway - exemplified by Team NZ in the lead-up to the 1995 Cup when they had waterfront pundits claiming that NZL-38 was vastly superior to NZL-32 - which was labelled a "dog".
Only when the "dog" was switched in the Semi-Finals of the 1995 Louis Vuitton Cup was the Kiwi's cover was blown.
Part of the testing process is that teams must confirm their baseline measurements or calibrate performance on the day to eliminate any unforeseen variable that has snuck in.
The teams also have to "test their tests", meaning they need to be sure that the testing is accurate on the day. This will involve using settings that will make a boat slower to check that the test analysis shows under-performance as much as it will exhibit improved performance. They will also check repeatable performance - to ensure they don't have a rogue result in the test performance data.
Whether they are altering one setting at a time or a combination depends on the test script for the day, and the sailing crews are in the hands of a test manager who calls the shots and brings discipline to the whole process.
The situation is further complicated if the teams use AI, which will produce some recommended sailing settings that must be tested on the water. It follows that some of these will work, and others will not.
The function of on-the-water testing is to verify these recommendations. Of course, it is not a simple case of ruling some in and others out - but looking at why an idea may not have worked and how it can be tweaked. The other approach with those which have worked is to keep the process of refining on a successful test result/direction/outcome. This process will usually keep running right through the campaign.
Of course, there is the interaction between changes that are made and how one change can affect the performance of another component positively or negatively. The phrase "trade-off" has been around for a long time in America's Cup sailing and is just as valid in the AC75 era as it was in the 12 Metre design days.
The situation is complicated by the teams being unable to change the declared configuration of a raceboat during a racing round, meaning a design direction must work in the lower end of the wind range as well as at the upper end.
In practice, light air performance to get the AC75 airborne is in many ways more important than how much faster a boat can sail above 50kts at the top end of the wind range.
However, as we saw repeatedly in the last Cup, and again in Vilanova last month, there is nothing quite so slow as an AC40/AC75 that falls off its foils and is slow to recover - while their opponent races away at speeds of 25-35kts - sailing at three or four times windspeed.
Or, achieves a similar outcome by simply sailing a more efficient course to the next mark.
AC37 Joint Recon Team Report:
American Magic - AC40 OD - October 5, 2023 - Barcelona
NYYC AM rolled out their two AC40s from the shed at 10.00hrs (Magic) and at 10:34hrs (America).
Both boats on LEQ12 mode, with the same foil configuration as yesterday and as last Monday in terms of arms, wings, and flaps.
Magic with the new foil wing and foil flap on the starboard side (FW4 and FF4); and with foil wing #1 and foil flap #1 (FW1 and FF1) on the port side.
America was composed with foil wing and flap #3 (FW3 and FF3) on the port side with no skeg; and with foil wing and flap #2 (FW2 and FF2) on the starboard side.
Both boats were craned to the water at 10:30 and 11:07, respectively; and they docked out at 12:10, as planned.
The same one-design sails were selected again for both boats. The MN3 for America and the MN2 on Magic. Immediately after coming out from the port, one-design J2s were hoisted at 12:25 approximately.
Today´s conditions were far from being the best ones for testing.
A weak ENE gradient wind, shifting persistently right in direction and dropping in intensity during the day prevailed.
In addition, some clouds came into play making it very patchy and hard for both boats to be sailing in the same breeze to permit comparable performances “without noise”.
The first part of the day consisted of speed testing.
Two long upwind and downwind were carried out. The only reliable conclusion was that on starboard tack on the upwind, America was faster and same angle, on both occasions and when positioned either to windward or to leeward of Magic.
On port tack, what can be said is that differences were smaller than the previous days, but nothing conclusive.
On the downwind the two boats alternated who was faster/lower, prevailing the one which was closer to the shore taking advantage of a different breeze.
The second part of the training from 13:45 till 14:20 was focused on tacks and gybes.
It was extremely hard to be able to get reliable conclusions on maneuvers not only due to the conditions of the day, but also given the fact that they were sailing on the lower range of their J2s, a small mistake on the trimming or steering had a big impact in performance, making them fall from the foils at times.
At 14:30 the one design J1s came up on both boats to replace the J2s, in the dying breeze.
During these forty-five minutes of the training not much could be achieved as it was tough to get both boats to line up foiling and flying consistently.
At 15:15hrs the breeze died completely and both boats were towed back to the base.
Both boats entered the port and lowered their sails at 15:35hrs, docked at 15:40hrs and were craned out at 16.06hrs (Magic) and 16:25hrs (America) indicating the end of the day.
[Sebastian Peri Brusa – Recon on NYYC AM]
INEOS Britannia - LEQ12 - October 5, 2023 - Barcelona
INEOS Britannia rolled out their T6 test boat at 10:00hrs.
Notably, the starboard side's banana foil was removed, with both the original elliptical foils in place. Though seemingly identical, ‘subtle differences’ have been confirmed between the two foils in a past interview. The foil arms do not seem to be updated in form, however have been re-painted. The rudder has been reverted back to a flat elliptical elevator. By 10:50hrs the mast was stepped, and the yacht was craned in.
The plan for the day was systems testing, as the team are focusing on aero and hydro control systems. Visible pre-sailing checks and systems tests included mast rotation, forestay and jib sheet system. Three batteries were carried onto the foredeck, replacing previous ones.
The M1-2 mainsail skins and J2-2 jib were prepared on deck ahead of 13:30hrs dockout (postponed from 12:30hrs). Dylan Fletcher helmed on starboard, with Leigh McMillan trimming and Ben Cornish in the 5th sailor seat. Giles Scott helmed on port, with Luke Parkinson trimming in front.
The yacht was released from alongside the chase boat after hoisting the mainsail and jib under the port entrance's breakwater. A brief pause in saw the sailors readjust tension by dropping the jib a few meters.
The yacht was then towed North, initiating a tow start 2NM offshore from the Forum.
Stint 1 commenced at 14:20hrs post-release of the towline, however the yacht fell off the foils following a tack. After half an hour sailing further offshore in displacement mode, another tow start was attempted but the lack of wind prevented the team from maintaining flight.
Ahead of Stint 2, the yacht was towed south toward the airport's sailing area, where the team found wind and started their session with a short upwind of four tacks. The yacht bore away and gybed onto a long downwind leg on starboard, followed by an extended upwind leg on the same side. The 35-minute sail ended with a technician boarding and investigating below deck, while sailors were seen looking up the mast.
Stint 3 saw a long upwind on port, followed by a brief downwind involving four gybes. The yacht was stopped through a two-board round-up, and a battery exchange occurred alongside the chase boat.
In Stint 4, the team sailed a long downwind towards Montgat of five gybes, 17nm as the crow flies.
During Stint 5, the team initiated an upwind on port tack, decelerating to displacement mode briefly before resuming foiling and continuing upwind to the port entrance, performing four fully foiling tacks.
The sails were dropped at the port entrance at 18:25hrs, and the yacht was towed back to base, docking in at 18:40hrs.
The Recon Unit covered 80 Nautical Miles observing the team’s five hour session on the water. 19 manoeuvres were performed, of which 75% were fully foiling.
Emirates Team New Zealand - AC75 - October 5, 2023 - Barcelona
Emirates Team New Zealand's third consecutive day of sailing aboard their last generation AC75 saw lighter winds than initially forecast with low grey cloud cover preventing the regular southerly wind flow from establishing itself.
That left a north easterly (060) breeze of around 10-12 knots at midday which faded to 6-7 knots by the end of the two and a half hour session.
Te Rehutai - B2 rolled out on time at 1030hrs and was rigged and launched by 1100hrs ahead of an on-schedule dock out at 1200hrs.
The boat was bow towed out of the harbour at 1215hrs with sails down but by 1225hrs the team had hoisted the J3-6 headsail and the M1-3 mainsail.
The boat was quickly airborne as the crew set off on a long upwind run during which they put in 10 tacks.
Boat speed upwind was in the mid-30 knot range. Notable once again as in previous days was the precision with which the crew sailed the boat with the bow dipped and so close to skimming the surface of the water.
During a half an hour of free-sailing up and downwind like this helmsman Peter Burling could be seen taking shots of the headsail. A brief stop at 1300hrs was followed by another long upwind run with 12 more foiling tacks before stopping at 1330hrs to rotate the cyclors, and – in response to the wind dropping to 6-7 knots – change headsail to the J2-6.
More upwind / downwind sailing followed with during the final downwind run the crew putting in 12 gybes - often with two in quick succession just 20 - 30 seconds apart. With the breeze fading considerably at this bottom end of the training area, time was called at 1425hrs. Sails were down by 1435hrs and the boat docked in at 1450hrs where the team's one design AC40 was waiting to be sailed in a separate second session. (No recon as the boat was in one design mode.)
Weather Observations - Port Olimpic
We are showing 48hrs of readings from the nowcasting station at Port Olimpic near the America's Cup racecourse at Barcelona. The reading were taken at a height of 12 metres, rather than at 2 metres above sea level, which is the case with the AC37 Joint Recon Team.
Average wind speed was recorded at 8-12kts at 1300hrs at Port Olimpic in a weather station. It increased in strength to 13-15kts by 1700hrs.
The direction was initially at 045 degrees (NE) at 1200hrs, swinging to 100 degrees by 1600hrs, and then making a sudden shift to the South (180 degrees) at 1630hrs.
Wave height was relatively low at 0.4metres.
This commentary was written and compiled from video, still images and statistical content extracted from the AC37 Joint Recon program and other material available to Sail-World NZ including photo files, and other on the water coverage from the 2010, 2013, 2017 and 2021 America's Cups. Weather information is by Predictwind