ANHEDRAL BEAUTY
It didn’t take long for the first major development to break-cover in this race to Barcelona for the 37th America’s Cup and today Emirates Team New Zealand revealed the first phase of its design development process with the sailing team, fresh from sailing in Dubai at the weekend, thoroughly testing a new port foil out on Auckland’s Hauraki Gulf.
The slender anhedral design (wing horizontals shaped downward) of the foil, set behind a sculpted bulb favoured by the Kiwis since their all-conquering design of AC36, is most likely a nod toward generating increased low-power lift and straight line speed as well as enhancing manoeuvrability.
If we relate the technology to aviation and look at high-manoeuvre planes such as military jets where the wings of the plane angle noticeably sharply down from the top of the fuselage, this is all designed to aid speed into the turns by creating lift on either side as the anhedral approaches the horizontal. In foiling dinghies where the boat can be hiked over to windward, having anhedral foils increases speed as the leeward anhedral wing rises to horizontal and gains lift in the vertical plane with the windward foil doing the exact opposite and the boat generates enhanced speed and righting moment with the boat effectively ‘rocked’ over to windward by the hiking sailor.
And this is what we saw today with the Emirates Team New Zealand AC40 noticeably ‘rocked’ to windward whilst on starboard tack with the port anhedral foil performing effectively. On port tack, the AC40 looked more upright and with the conditions in Barcelona likely to be changeable, having the ability to generate lift whilst maintaining flight, particularly out of manoeuvres, will be at a premium.
And boy did they do some tacks and gybes today! With Nathan Outteridge and Pete Burling back in Auckland and back on the wheels, the Kiwi testing programme was intense with a solid three and a half hour session that saw a total of 59 gybes and 39 tacks. Clearly the data gatherers in the ETNZ design office had put together a thorough training schedule for the sailors with specific data requirements around the handling of the AC40 and with 6-11 knots of breeze in the afternoon and flat water, it was the perfect day to start throwing the highly manoeuvrable AC40 around the harbour. After a couple of opening trial tacks and gybes onto the new foil resulted in splashdowns, the team were quickly into their stride, executing beautifully and taking off at circa 13 knots whilst really concentrating on the starboard tack heel technique on the longer legs and runs around Tiri Tiri Martangi Island. (Magnus Wheatley)
The on-water recon unit’s observations regarding the new foil were: “Curved anhedral, looks to be smaller in area than the one design. Pointy tips, flaps look to be composite but could be paint. Flaps are dull in colour and do not look metallic.”
The design race for the America’s Cup just got very interesting.
On-Water Recon Unit Notes: Good session on the harbour between Rough Rock and about 4 miles south of Tiri Tiri Martangi Island. Boat looked fast but twitchy. Some very slick manoeuvres but in the beginning of the session some dud gybes and tacks going onto the new foil (learning its subtleties?). Lots of manoeuvres and some straight lining. I think they looked at modes upwind for a little but only a few minutes was spent on this.
Helms: Nathan Outteridge, Pete Burling
Crew: Andy Maloney, Blair Tuke
Conditions: 6-11 knots from NNE in afternoon, 23 degrees, partially cloudy.
Dock-out: 13.05 Dock-In: 16.35
Take off speed: 13 knots at 80 degrees TWA (True Wind Angle)
Sails Used:
M1 (OD): 3 hours 30 minutes
J2 (OD): 2 hours 45 minutes
J3 (OD): 45 minutes