J Class (yacht)

The J Class of racing yachts (sometimes called "J-boats") were built to the specifications of Nathanael Herreshoff's Universal Rule.

The J Class is considered the apex of the era when the Universal Rule determined eligibility in the America's Cup.

Where: The numerator contains a yacht's speed-giving elements, length and sail area, while the retarding quantity of displacement is in the denominator.

A table of well-known J Class yachts demonstrating that application of the Universal Rule could result in a rating

Yacht designer Clinton Hoadley Crane noted in his memoirs that "America's Cup racing has never led to good sportsmanship.

"[8] In 1930, Thomas Lipton spent $1,000,000 for his Shamrock V challenge when America was facing a stock market crash, but the NYYC still built four cup defenders.

The rivalry led both countries to put on a display of true technological innovations using the maximum load waterline length authorized by the rule for Endeavour II and Ranger in 1937.

The larger scantling would prevent the frequent dismastings that had been previously observed in the British Big Class season of 1935.

By the 1980s only three J Class yachts were still in existence: Shamrock V, Endeavour and Velsheda, all designed by Charles Ernest Nicholson.

Several replicas and original designs were subsequently built and the association now organizes races for the J Class in Newport, Falmouth and Cowes.

The current J Class fleet comprises nine boats: Endeavour, Hanuman, Lionheart, Rainbow, Ranger, Shamrock V, Velsheda, Topaz, and, launched in January 2017, Svea.

Other boats raced in J Class regattas: the yachts Katoura (Starling Burgess, 1927), Resolute (Nathanael Herreshoff, 1914) and Vanitie (William Gardner, 1914) served as trial horses and most International Rule 23mR yachts were converted to the J Class, of which three remain in existence: Astra, Cambria and Candida.