ISAF International A-Class Catamaran Class Rules

The A Class Catamaran is controlled by the rules set down by the ISAF under the "Rules for the Divisions of Catamarans and The International C Class" (last issued May 1985) which are as follows:

  1. A catamaran is defined as a two-hulled sailing boat with essentially duplicate or mirror image hulls, fixed in parallel positions.
  2. Sail area shall not be more than 13.94 square meters (150 square feet)
    Sail area to be measured in accordance with the "IYRU Measurement & Calculation of Sail Area Instructions" (last issued May 1985).
  3. The over all length of the catamaran shall not be more than 5.49 meters (18 feet).
  4. The length shall be measured between perpendiculars to the extremities of the hulls with the catamaran in her normal trim. The measurement shall be taken parallel to the centre line of the craft and shall exclude rudder hangings, but if the athwart ships width of a rudder within 153mm (6 inches) of the bottom of the hull is more than 76mm (3 inches), the length shall be taken to the aftermost point of the rudder.
  5. The extreme beam shall not be more than 2.3 meters (7ft 6.5inches).
    The beam shall be measured at right angles to the centre line of the craft at the widest point and shall include hull appendages in all positions (completely down and completely up flush with the bottom of the hull).
  6. The crew in Division "A" shall be one person (helmsperson).
    An unballasted retractable seat or trapeze shall be allowed for the helmsperson.
    When in use the helmsperson at all times shall have at least one foot in contact with the boat.
  7. The A Division emblem shall be carried on the mainsail and shall consist of the letter "A" over two parallel horizontal lines over national letters and sail numbers.
    Sail numbers shall be allotted by the National Authority or Class Association appointed by the National Authority. The class emblem, national letters and distinguishing numbers shall be placed as prescribed in the Racing Rules of Sailing (RRS 77 & RRS Appendix G).
  8. 8.1 No part of each hull or hull appendages below the waterline shall be less than 0.75 meters from the centre line.
    8.2 Movable and retractable hull appendages shall be inserted from the top or be capable of being fully retractable into the hull.
  9. Minimum weight in full sailing trim shall be not less than 75 kilograms.
  10. 10.1 The International Class fee shall be paid every year to ISAF.
    10.2 From 1 January 2010 all new boats shall have ISAF plaques affixed to the starboard transom.