Before the J Class yachts came into existence, yachts were designed to be bigger and bigger. The towering rigs of the Big Boat Class such as 'Lulworth' and 'Britannia' dwarfed all other yachts. The late 1920s heralded discussion and agreement of the Universal Rule. This new formula controlled the size and displacement of the new yachts, enabling them to be raced as evenly as possible. Almost immediately, designs were being commissioned for the new, massive 'Bermudan rigs, with no bowsprits'.

The rule was based on ideas proposed by Nat Herreshoff allowing waterline length to be increased without sail area being restricted, as it had been under the International Rule. This was compensated by a larger displacement and so draught was limited to 15ft.