mardi 13 août 2019

AMERICA'S CUP 2021: THE AC 75 drawings

AMERICA'S CUP 2021: THE AC 75 (EV)


DRAWINGS OF AN AC75 
&
SILHOPLES
AMERICAN MAGIC, LUNA ROSSA, INES, STARS&STRIPES & ETNZ



Very soon after the 35th America's Cup sailed in Bermuda with the AC50 catamarans which saw Emirate Team New Zealand's victory over the defender Oracle Team USA, from 17 to 26 June 2017, the time was right for a decision to change the type of boat to sail the next edition in 2021.

As of September 11, 2017 the new trophy holder, Emirate TNZ, confirmed Patrizio Bertelli's proposal, boss of the Challenger of Record, to race the competition on high performance monohulls. 



On November 20th of the same year, after debates between potential designers, the concept of this monohull - the AC75 - was revealed. It will allow designers more freedom, with the only advanced restrictions intended to ensure that competitors' prowess will remain as homogeneous as possible.

This monohull with ballasted foils surprising as it is, had already been imagined some time earlier by the French yacht designer Guillaume Verdier and the British engineer Dan Bernasconi. The two colleagues - they work in the Emirate design team - had developed this concept of a 12 metre long monohull fitted with ballasted side foils, to offer it to a  New Zealand customer but unfortunately the boat was never built. 


When they were asked to present a hydrofoil monohull for the next Cup they obviously pulled out their dossier....


Thus in 2021, Auckland, it will be necessary to sail strange sailing boats without keel and more aerial than ever: the AC75 fitted with ballasted foils and propelled by "classic" sails. A beautiful way to celebrate the 100th anniversary of  the American brothers Malcolm and Thomas A. McIntyre's dream (never built).



But it was not until the 1950s that another American, Gordon Baker, achieved the unthinkable by flying a monohull for the first time: Monitor...


AC75 - SPECIFICATIONS

Monocoque à foils/Monhohull with foils
Sloop à grand-voile double/Sloop with double main sail

Mise à l'eau des premiers voiliers/First AC75 launching – août/August 2019
Longueur/LOA - 20,70 m
Flottaison/LWL - 20,70 m

Bau/Beam - 4,80 à 5,00 m

Entre-axe des foils/ Center distance between axes - 4,10 m
Bau max avec foils/Maximum beam with foils - 14,10 m
Tirant d'eau max avec foils/Maximum draft with foils - 5 m

Tirant d'air/Air draft - 28 m

Bout-dehors /bowsprit - 2,16 m
Déplacement léger/Light displacement - 6,450 t
Déplacement lourd/Heavy displacement - 7,57 à 7,6 t
Foils/Foils weight - 2,430 t
Surface de la GV/Main sail area - 145 m2
Surface du foc/Jib area - 90 m2
Surface du Code Zéro/Code Zero area - 200 m2
Équipage/Crew - 11 + 1

ILLUSTRATIONS

1 — The Mule

This hydrofoil monohull on which the team of the New York Yacht Club's challenge for the America's Cup American Magic is training. As its name implies, The Mule is a draft scale model of the AC75 that will race the Cup in 2021 in Auckland. 

The advantage of the ballasted foil is that in the event of a capsize the boat can right itself, and above all it improves the ability to sail in strong winds. This last point is essential as the regattas should be cancelled above 24 knots of wind in 2017. 

Rather than wings as it was the case in the past three Cups, New Zealanders preferred profiled sails with a double thickness, easier to set up and less expensive.


Longueur/LOA -11,58 m
Bau/Beam - 3,30 m
Bau foils sortis/ 8,10 m
Bau max avec foils/Maximum beam with foils - 4,95 m
Tirant d’air/Air draft - 18 m
Vent minimum pour le décollage/Minimum wind - 5 /7 nœuds/knots
Surface de la grand-voile/Main sail area - 52 m²
Surface du foc/Jib area -34 
Déplacement/Displacement - 1,8 tonnes
Équipiers/Crew - 5

2 – Comparison

The wing of the 2013 AC72 remains impressive and it is understandable that the crews sweated cold. The choice of a small hydrofoil catamaran in 2017 remains well fitted with sails compared to the length of the most modest yachts in the history of the America's Cup. 

On the AC75, the centre of pressure of the sails is very low to be able to race in a stronger wind than in previous editions.


3 - Three views of Luna Rossa, as presented in a scale model

The cockpit is very open, the deck layout is inspired by the latest TP52 but with two very advanced wheel steering systems.


4 – AC75 Lines

Barely 7.6 tonnes for a hull of 20.70 metres long by 5 metres of beam maximum, the narrow waterline: 3.70 metres, flat bottoms, sections close to a bilge hull and highly stretched lines such as few monohulls. It is likely that some hulls will be even more extreme.


5 - AC75 American Magic outline


6 - AC75 Luna Rossa outline


7 - AC75 Ineos outline



8 - AC75 Stars&Stripes outline


9 - AC75 ETNZ outline


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