A little history
The rules of the America's Cup, laid down by the"Deed of Gift", a reference document dating from 1851 and still in force, has always given the Defender considerable power (the defending champion and over this 35 e Oracle Team USA edition). The latter decided, for this 35 e edition, to reduce the size of the boats, to propose a platform and a wing almost monotypes, to limit the number of days of navigation to 150 before the competition, and finally to authorize each trade union to build only one boat for the event.
The Class AC were launched in the spring and the challenges involved in the Cup have circumvented the rule, implementing a version 1 of the AC Class The latter's replica is 1.50 metres shorter. It validated all the systems and manoeuvres found on the final version of the AC Class.
The Class AC, a 15 m long hydrofoil catamaran
For this 35 e edition of the America's Cup, the regattas will take place on 15 m one-design boats - AC Class - in place of the large 22 m multihulls used in 2013 or the AC62s that were expected for a while.
This catamaran has rigid wing - which replaces the mainsail and mast - measures 6 m less than the previous model, but will be just as fast since equipped with foils . It will also be able to fly over water at about 40 knots (74 km/h) thanks to the reduced friction of the water on the hulls. If in monohull, speed is related to the length at waterline (the bigger the boat, the faster it goes), this is not the case on hydrofoil catamarans used for the America's Cup. Today, even by limiting the power of the engine (in this case the wing), by reducing the weights thanks to the materials used, the performances increase unceasingly, in particular by the means of the servo systems making it possible to optimize the adjustments of the foils in flight.
Some elements of the boat are common to all competitors, while others are left to team development.
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Monotype elements |
Free elements |
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- ||||||Shape of the hull - Width - ¶ ¶ ¶ ¶ Sail area - ¶ ¶ ¶ Cockpits ¶ - ¶ ¶ ¶ ¶ Pod on which the wing rests¶ |
- |||||| Wing structure - Appendices (rudders and foils) - | Electronic and hydraulic control systems - ¶ ¶ ¶ ¶ Careenages |
Length: 15 m
Max width: 8.48 m
Max draught: 2.40 metres.
Wing height: 23.60 m from the mast foot.
Focus on the main components of the AC Class
The wing
The wing is composed of 3 elements: the monotype mast which lands on a 60 mm diameter ball positioned on the platform, the front part and the rear part (itself composed of 3 elements called flaps).
Between the two flaps, hinges are used to orient the different elements and each joint can be turned by means of a quadrant. The front part of the wing being frozen, the goal is to twist and to camber the flaps by putting different angles if necessary.
There are two possible amplitudes: the camber and the twist.
- The camber When there is little or no wind, angle is used to dig the wing. When there is wind, we try to flatten the wing.
- The twist This movement is performed when you do not want to have the same level of force at each level of the wing.?En the top of the latter in particular, the flap can work"upside down", unlike a classic sail to increase the performance of the wing.
The Appendices
The appendages allow the boat to lift thanks to the speed. There are two types:
The L-shaped foils can be swivelled, retracted and positioned behind the front arm. In carbon, they are composed of two parts:
- The upper part of the appendix called Shaft
- The lower part called Tip
- The junction between the two called the knee or elbow
The rules impose a maximum number of Shaft and Tip on the AC Class, only 4 highs and 8 lows are allowed. The lower part, the Tip, must not represent more than 30% of the foil's weight, but is not limited in length.
Groupama Team France, like its competitors, adapts the foils according to the wind ranges and builds two types:
- Small to medium time foils with longer Tip
- Foils with shorter Tip, optimized for higher speeds
Photos: Eloi Stichelbaut
