 Within that rule there is a "One Design" subclass which covers boats built to a one design rule in operation between 1971 and 2007, all of which have the same hull shape and are subject to an 83 kg minimum weight limit.The third division, known as the AC (Asymmetric Canoe), uses the 83 kg one design hull and carries an asymmetric spinnaker.The combination of an easily driven hull with a highly developed and efficient sail plan, and the powerful righting moment afforded by the (single) crew positioned well away from the hull centerline provides possibly the most exhilarating and technically challenging sailing experience available in a mono-hulled craft.