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The Debrief: How the America’s Cup was Powered

by Ingrid Hale
Art Powering Cup Winners

The art of creating power through wind, human strength and design is an ancient obsession that has trickled down and created space for modern-day flying machines.  We look at the evolution of how boats were powered in The America’s Cup.

The sport of sailing has traditionally maintained strict rules against the use of stored power such as the use of engines to help adjust or trim rigging and sails, limiting this to crew manual power only, albeit assisted by the use of levers and pulleys and screws. More recently, World Sailing permitted Class Rules to fully, or partly relax these restrictions, opening up opportunities to use non-manual power aboard racing yachts to power movable keels, adjusting riggings and trimming sails, resulting in bigger loads and more speed.

Some of the first sheet winches, with 1:1 gearing, were in use in yachts in the 19th century. Nat Herreshoff refined them and used winches aboard Reliance, the largest yacht ever to race for the America’s Cup. These were handed down to Resolute in 1920 and Enterprise in 1930. It was not until 1959, that the modern top handled winch was invented and sold by Lewmar. Later, multi-geared winches became available and are now common aboard most modern keel yachts.

The 201ft long Reliance crossing the finish line in the 1903 America’s Cup


Interestingly, the Deed of Gift provides only that a Challenger’s yacht must be “propelled by sails only”, but the Deed has no such requirement for a Defender. Could a Defender use an engine-powered yacht? The highest court to rule on the Deed, the New York Court of Appeals, helps a Defender as it ruled in the Mercury Bay case, “… the deed permits the competitors to both build and construct and race the fastest vessels possible so long as they fall within the broad criteria of the deed. … Any question of sportsmanship and fairness, such as the propriety of races between monohull and multihull vessels, … are not questions suitable for judicial resolution.” More than a few candles were burned investigating this between 2007-2010!

The giant multihulls of the 33rd America’s Cup in 2010.

It was the 2010 America’s Cup match, raced under the terms of the Deed of Gift that brought non-manual power into racing for the Cup.  The Defender took the opportunity available under World Sailing’s Racing Rules of Sailing, to relax the manual power rule (which it routinely did anyway for some of its racing on Lake Geneva). This was objected to by the Golden Gate Yacht Club, but it lost this argument in the New York Supreme Court and Golden Gate was forced to belatedly add an engine to help power its yacht. Both yachts raced the 2010 match with a small engine providing additional non-manual power to help sail their huge multihull yachts.

The more recent America’s Cups held in 2013 and 2017, understandably eschewed environmentally unfriendly combustion engines in favour of hydraulically powered systems, where hydraulic power was provided by the crew (grinders) powering pumps to store hydraulic pressure which was bleed off as sails and foils were trimmed. Emirates Team New Zealand’s decisive innovation in 2017, was the use of more powerful leg power of four cyclors to provide greater power.

Emirates Team New Zealand’s cyclor powered their winning AC50 in the 2017 America’s Cup


In 2021, additional power will be provided by rechargeable batteries providing electrical power to control and trim the foils while the grinders will again be providing hydraulic power to trim sails – but limited to arm power this time! Will this now make the America’s Cup less athletic than in the past? Peter Burling’s response to this is The grinders this time will have to be at a very high athletic level. The AC75 is a very powerful, dynamic boat that is very energy-intensive to sail, so the demands from the athletes are very high”

Art Powering Cup Winners

© Emirates Team New ZealandEmirates Team New Zealand’s AC75 Te Aihe training in Auckland in 2019

This article was originally written for by Dr Hamish Ross on 27 May 2020

[The Debrief: The Art of Powering Cup Winners]

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