AC72

Development
Design	Box rule
Boat
Crew	11
Draft	4.4 m (14 ft)
Hull
Type	Catamaran
Hull weight	5,900 kg (13,000 lb)
LOA	26.2 m (86 ft)
LWL	22.0 m (72.2 ft)
Beam	14.0 m (45.9 ft)
Rig
Mast length	40.0 m (131.2 ft)
Sails
Mainsail area	260 m2 (2,800 sq ft) (wing estimate)
Upwind sail area	580 m2 (6,200 sq ft) (wing and gennaker estimate)

The AC72 (Americas Cup 72 class) is a wing sail catamaran box rule, governing the construction and operation of the yachts to be used in the 2013 Louis Vuitton Cup selection series and the 2013 America's Cup. This new and revolutionary design is extremely expensive and has allowed the development of foils which lift the hull out of the water in some conditions leading to extreme speed and potential danger.

History

The AC 72 yachts, according to the 2013 AC protocol, cannot be launched prior to July 2012 for testing. Racing will begin 2013. Designers and builders for each team will create their own hulls, wings, soft sails, and underwater foils within the confines of the rules, and will be allowed to test and refine their designs prior to the official measurements for the races. The AC 72 New Zealand was launched in August 2012 and in trials in early September exceeded 40 knots in 17 knots of wind while sailing to windward in small to moderate seas with almost no heeling. The New Zealand has a wing mainsail. The New Zealand has hydrofoils that lift the entire hull clear of the water so there is almost no wetted surface area. The windward foil is retracted with only the leeward foil in operation at this speed. The speed was achieved while carrying media on board. The foils are part of the normal high aspect ratio dagger boards with the lifting foils at right angles to the bottom of the dagger board and about 1 meter long. Because of the abnormally high speeds crewmen wear safety helmets on board. Team Oracle uses a similar foil /daggerboard combination but the lateral foil is longer at about 1.4 m. Oracle uses a small T shaped foil near the bottom of the rudder blade and the New Zealand boat has similar rudder foils. In October 2012 a yacht designer commented that the New Zealand AC 72 seems to be far ahead of other contenders, regularly exceeding 40 knots and sailing in very strong winds without breakages that have plagued the Oracle design. He said the New Zealand boat seems to be 10 to 20% faster than other contenders at this stage. The New Zealand design is very stable on its foils for sustained high speed bursts of up to five minutes. A spokesperson for the New Zealand team said that the boat is performing according to the design physics. He did not comment on the articulated prod or the unusual curved angle of the two dagger boards. A French designer, working from photographs, has published hull lines for the New Zealand AC 72 which shows very flat, high lift, under water sections extending well forward. Above the waterline the hull sides curve inwards in the forward sections to reduce weight. At foiling speed this also reduces the coefficiency of drag as speeds rise above 35 knots. Most of the AC72 catamarans for the Americas cup are being currently built in Auckland, New Zealand, the world center for high performance sail boats using carbon technology. Team New Zealand announced that it will share technology secrets with the Prada sponsored Luna Rosa which is being built and sailed in Auckland. Teams are restricted to 30 sailing days so this speeds up both teams' developments. Luna Rosa will have all their team and families based in Auckland as they have with previous Americas Cup contests.

Kiwi Asim Khan, who has studied at Auckland, Victoria, Karachi and South Alabama Universities and previously worked for Telecom New Zealand, is IT director for Team Oracle, said their AC72 is equipped with hundreds of sensors which feed information via WiFi to crew members wearing special watches or to deck mounts near grinders. He said the system is simple and works well and is a lot more reliable than previous systems. It is not known if the electronic system was still operational after the boat suffered its spectacular capsize in salt water.

On October 17 at San Francisco, the USA Team Oracle AC72 suffered severe damage during one of the permitted 30 day trials. The AC72 failed to foil in strong winds when it bore away in 25 knots of wind, nosedived and experienced a bow to stern capsize / overturn. The wing mast broke, loose equipment sank, and the boat was dragged by the current 5 miles before being towed upside down back to base. Oracle's wing mast was destroyed but the hull appears to have suffered only minor damage. It is uncertain if the incident was caused by design flaws, construction faults, or crew error. This follows previous damage when a foiling dagger board snapped off in moderate conditions. Coutts, the ex New Zealander behind the American design has admitted the design is too complex and very expensive at $8 million US each. The American design has been plagued with problems since its launch. Comments from Americas yachting press indicate that Team Oracle may have serious design problems with its foiling system. The USA AC72 appears unable to sustain sailing in foiling mode for more than a brief period even in medium to heavy winds. This may be due to excessive weight or to poor foil design, which are important factors in unstable foiling.

The Luna Rosa AC72, which is a replica of New Zealand's AC72, was launched October 26, 2012. Skipper Max Sirena believes that the New Zealand team with a great crew and a fast boat are currently the clear favourites. The Italians hope to be out on the water by next Wednesday. Sirena felt they had a design edge over Oracle, suggesting the American's problems lay with the stiffness of the cat's platform. Italy, with a $90 million budget, will restrict themselves to one boat. Italian boss Patrizio Bertelli criticized the AC72 for its extreme cost which has limited the number of entries to four compared with about 20 boats when the America's cup was sailed in monohulls. The fourth boat is the Swedish challenger Artemis Racing, which was damaged while being towed in San Francisco last week. On their 15th day of testing Team New Zealand team took the media out on the boat during light weather testing. New Zealand team manager Grant Dalton said he had seen some good features in Oracle that they will be incorporating in the second New Zealand boat. Dalton said so far their testing has been mainly in moderate to heavy weather with the boat regularly exceeding 40 knots in under 20 knots of wind . October has been extremely windy in Auckland. Team members wear life jackets, helmets and carry under water breathers which allow them to breathe under water for a short period if the boat flips.

Team New Zealand and Luna Rosa started racing against each other after the Italians' 5th day of testing, watched by a Team Oracle spy boat on the Hauraki Gulf, in light warm weather. Luna Rosa has won praise for its exquisite mirror finish silver hulls. One big difference from the team NZ boat is the design of the dagger board foils which appear conventional alongside the Kiwi foil design. The kiwi chase boat built by Salthouses and skippered by Curly Salthouse is powered by four 300 Hp outboard motors so it can keep up with the Team NZ AC72. The top speed of the loaded chase boat is 58 knots.

Team New Zealand announced that they have finished their 30 days sailing, 2 days ahead of schedule. Last week during a severe Auckland storm, which included a tornado and winds up to 140 km per hour, New Zealand's AC72 recorded sustained speeds of 42 knots and averaging 32 knots while tacking down wind over a distance of about 15 km. English yachting commentator Martin Tasker said that even in these conditions the kiwi team is very professional, calm and competent and push their boat hard . Team New Zealand manager Grant Dalton said that the design team have analysed the data downloaded from the various sensors and are confident they can make the second boat significantly faster.

Oracle manager, Russell Coutts, speaking at the presentation of NZ yachtsman of the year award in Auckland, admitted the near sinking of the Oracle was due to errors by the skipper of Oracle in being too over confident. He said the rescue was far slower than it should have been which led to more loss and damage to gear on the overturned catamaran. All this had been a major setback but he said the Oracle team had learned from their mistakes.

Grant Dalton announced that the construction Team NZ's second AC72 is well ahead of schedule and will be launched within the next 2 weeks. Currently it is having complex new controls fitted (possibly computerized). It is believed that the first Team New Zealand AC72 used electronics to control or partly control the rise and fall of the hull on its foils. It appears the new boat may have an updated, more sophisticated system. Team NZ technology director Nick Holroy says some areas of the new AC72 have been lightened and others reinforced. He did not comment on whether the distinctive curved foils of the new craft, which create a V shape lifting surface well inboard of the leeward hull, are based on surface piercing technology.

Team NZ and Team Prada have been match racing their 72 ft catamarans to hone their racing skills at Auckland this summer. Competition between the 2 teams has been fierce. The weather is Auckland has been very warm and fine with regular strong afternoon sea breezes. Video shot of the catamarans shows them sailing close together at high speed and maneuvering within 18 inches at buoys.

A leading French yachting scientist, specializing in hydrodynamics, has speculated that Team New Zealand has invented a revolutionary way of keeping its AC72 stable while foiling, by using a system he described as an S stop incorporated in its foil design. This creates a clever V shaped 22 degrees dihedral surface piercing foil, enabling their boat to remain automatically stable without direct input from the helmsman. This would account for the lengthy and regular high speed bursts of incredible speed that have been filmed regularly in Auckland, where their AC72 approaches 3 times the speed of the wind. Even more remarkable is that the team continued its sailing program in strong hurricane strength winds in December in Auckland, without suffering any damage and remaining in control at speeds that are alleged to have exceeded 50 knots.

New Zealand's second generation AC72 which incorporates many subtle but significant changes, was launched today by ex Olympian Mandy Barker, wife of skipper Dean Barker, at Auckland. The new boat was blessed by the local Maori tribe and named New Zealand (Aotearoa). Yachting journalists, briefed by team NZ suggest that many improvements have been made to the shape of the main sail, possibly to enhance sail shape in the very high sailing speed range, 40-55 Knots. The journalists were told that more time went into redesigning the second boat, than actually building it. Team Oracle completed their 9th sailing day in very light winds on 6 February. The team is anxious to rebuild their confidence in their rebuilt boat. The AC72 being used is a rebuilt version of the original that capsized and was partly destroyed, due to crew error, according to Russell Coutts. Concerns have been expressed in the yachting media that Oracle's foiling design is faulty and they are so far behind in their development program. Despite these critiques, it should be noted that Oracle Team USA has 2 extra months to prepare and reevaluate their designs because they are the Defender.

The team NZ boat New Zealand Aotearoa was launched on 3 February 2013, had its first sail in light, warm conditions at Auckland. Afterwards the skipper and manager pronounced themselves satisfied with the day's testing. On March 5 the New Zealand media was invited on board Aotearoa/New Zealand for trials in Auckland Harbour. Team New Zealand's Grant Dalton said the new boat accelerates from 20 to 40 knots in 1.5 seconds, making it considerably faster than the first boat. In a run down the harbour the pace boat that has a top speed of 58 knots, was left far behind. Team New Zealand today had a match race with Team Prada beating them by a wide margin. Aotearoa averaged 39 knots around the complete course in 17 knots of wind. The skipper Dean Barker said they know that new boat is considerably faster than the first boat. Barker said at one part of the course the boats were approaching each other at a speed of nearly 100 knots. The crew of Aotearoa have had special training from a high dive tower in case their AC 72 capsizes. They jump wearing their special sailing suits into a 10m deep pool. They crew have undergone training to increase their speed and agility to improve their movement between the hulls .

List of AC72 catamarans

Syndicate	shipyard	notes
Team New Zealand	Cookson Boats	boat #1 launched and christened New Zealand on July 21, 2012. hydrofoiling capability. Decommissioned.
Oracle Racing	Oracle Racing	boat #1 launched and christened 17 on August 30, 2012. hydrofoiling capability. Partially destroyed in October 16, 2012 capsize
Luna Rossa	Persico	Launched and christened on October 26, 2012. hydrofoiling capability
Artemis Racing	King Marine	boat #1 launched and christened on November 3, 2012. Currently undergoing improvements at Artemis base in Alameda, CA
Team New Zealand	Cookson Boats	boat #2 launched and christened New Zealand Aotearoa on February 3, 2013. hydrofoiling capability.
Oracle Racing	Oracle Racing	boat #2 building, scheduled to be launched sometime in April 2013.
Artemis Racing	King Marine	boat #2 building

See also

• 2013 America's Cup

External links

• AC72 Class rule