This introduction only provides an informal background and the International Nacra 17 Class Rules proper begin on the next page. Nacra 17 hulls, hull appendages, cross beams, trampoline, rigging and sails are manufacturing controlled. Nacra 17 hulls, hull appendages, cross beams, trampoline, rigging and sails shall only be manufactured by Nautical Sports BV– in the class rules referred to as ‘Nacra licensed suppliers’. Equipment is required to comply with the International Nacra 17 Building Specification and is subject to a World Sailing approved manufacturing control system. Nacra 17 hulls, hull appendages, cross beams, trampoline, rigging sails may, after having left the manufacturer, only be altered to the extent permitted in Section C of the class rules. Owners and crews should be aware that compliance with rules in Section C is the responsibility of the competitor, as this is NOT checked as part of the in house certification process. Rules regulating the use of equipment during a race are contained in Section C of these class rules, in ERS Part I and in the Racing Rules of Sailing.