As early as 1914, forums were held to find solutions to secure the future of the Rule but before anything could happen, priorities changed as the Great War intervened. In between 1917 and 1919 the Yacht Racing Union headed by Heckstall-Smith worked on developing the formula to something that would produce more wholesome yachts. This would result in the most radical change in the history of the rule as the beam would be discarded from the formula and replaced by a minimum of one foot per metre rating. (A pretty unique combination of the metric and imperial measurement systems as the minimum beam for an 8-Metre would be 8 feet, a 12-Metre, 12ft and so on.) Girth penalties were raised significantly and sail area was penalised much more severely. As the rule was young and only few boats had been built, the 1920 Olympics in Antwerp competed in two groups, the old and the new rule boats. The development in the first four years was again frantic with ideas tested to the extreme. The 1924 Olympics in Le Havre displayed the earliest wholesome 8-Metres the most successful being, Bera by Johan Anker, Emily by William Fife and BlueRed by Charles Nicholson. The shapes developed further with more emphasis on length and less on sail area with more draft and displacement to the shapes of the famous Aile VI and Hollandia who were the best boats at the 1928 Olympics. Naval architects now seeked their advantage in the extreme ends as boats were stretched to gain sail area by reducing bow and stern girth measurements. The rigs developed, mast scantlings were developed and the maximum hoist of the jib was fixed at 82.5% of rig height. In 1927 the overlapping genoa was introduced, taking full advantage of the unmeasured thus free headsail area aft of the mast. The rule was good and produced exceedingly fine boats and enjoyed tremendous popularity. The only agreed serious flaw remaining was the 1/4G measurement which resulted in insufficient keel depth and tender boats. Johan Anker’s Silja and William Fife’s Saskia are the best examples of how that was addressed by designing boats with more beam thus adding more form stability. In 1928 North America finally accepted the International Rule for the small classes, i.e. 6, 8, 12-Metres while Europe adopted the Universal Rule J-Class for the largest of all classes.
Despite the great success of the Rule, it was still felt that improvements could be made and at its expiration in 1933 this was addressed.