America's Cup: Emirates Team New Zealand flies Code Zero
by Richard Gladwell/Sail-World NZ 7 Oct 20:15 PDT
8 October 2019
Emirates Team New Zealand sailing with a Code Zero in light airs on the Hauraki Gulf, October 8, 2019 © Richard Gladwell
Emirates Team Team New Zealand had a foreshortened training session on the Hauraki Gulf this morning after their Code Zero let go.
Light winds average less than five knots and gusting a little higher prevailed for today's training session which saw the Code Zero set from the bowsprit for the first time on the AC75.
Soon after breaking away from one of the chase boats, shore-side observers reported that the AC75 was initially sailing fast but not foiling, before helmsman Peter Burling pulled away to sail a deeper wind angle.
Eyewitnesses reported that the AC75 then rolled slightly to windward as the lift from the leeward foil kicked in, and Te Aihe lifted up to be foil borne, and then returned to a higher sailing angle.
A few minutes into the sail, there was a breakage in the tack area of the Code Zero/bowsprit, and the sail streamed to leeward before being retrieved by her crew.
After continuing under mainsail for a while, the crew decided to give away the test session, before dropping the main to return to their base in the Viaduct Harbour just afternoon.
The America's Cup Defender has been putting in long hours in the days they have been able to get on the water, as they shake down the AC75 and acquire valid test data to be used in the design of their second AC75. However, the spring weather in Auckland has been against them with only four sailing days in the last ten.
The sailing to date has been mostly in fresh winds of 15-22kts, according to automated wind recording stations around the America's Cup course area.
While today was not the first light weather sailing for the Kiwis, the first few sails was marred a little by a mainsail hoisting issue. However, those now appear to be resolved.
Head designer Dan Bernasconi told Sail-World at the launch of Te Aihe a month ago that it was "difficult to know at this time (pre-launch) as to how much time the boat will be in the water and how much time flying. It may be in really light conditions we may be touching down very frequently.
"It is definitely something which we have in the simulator, but which we'll learn on the water and be able to validate that simulation and get a better idea of what those weights should be.
"We don't have long to do that because we have got to get into our second boat really soon."
Bernasconi went on to say that the use of the Code Zero and understanding how could be deployed was "probably hardest learning from the simulator".
"It is a good question about the Code Zero because when you are not foiling you'd love to have a Code Zero to help you accelerate in non-foiling conditions.
"But having a big sail like that when you are up and foiling you can quickly get to an apparent windspeed are carrying a lot of sail area when you don't want to. That is definitely one of the main things we want to find out about in this boat."
Although the team would not comment on the breakage, it is understood that it was a minor part that was difficult to fix on the water.
If the issue happened when the boat was put back to a higher sailing angle (which will also cause the apparent wind strength to increase substantially), it underlines the extent to which the sails, even light weather sails need to be versatile and able to be sailed in wide wind range than would be the case with "normal" race boats.
The Code Zero was last used in 2013 in the AC72 wingsailed foiling catamarans, the AC72 Code Zero was a bigger sail than that carried on the AC75, with a bigger overlap over the wingsail.
On the AC72 the cross-over to the jib only was around 10kts - considerably higher than today's windstrength. Conditions in the Gulf were marked with significant glassy patches - indicating no or little wind (and visible in the sailing images). Te Aihe was sailing in the breeze, but not far from a "flat spot".
The fact that she was able to get foiling in such conditions is significant.
The breakage (assuming it was not a manufacturing/build fault) is indicative of the high loads that the AC75 is generating, even in light weather.
The team is expected to be able to sail for the rest of this week, except maybe for Thursday when fresh seabreezes are predicted, gusting to 30kts, easing on Friday.