Sailcut CAD. Sailcut is a software for designing boat sails and developing then into flat panels. Sails can be either 4 sided sails like for old timer gaff rig or 3 sided sails like jibs or main sails for Marconi rig. The first version of Sailcut was developed in 1978 and used by Robert Lainé for making the sails of his IOR 1/4 ton named ”Flying Sheep III”. Sailcut has been available on the web since 1994 and is used by many professional and amateur sail makers for offshore racing, cruising and recently for model yacht. Sailcut uses a unique mathematical definition of the surface of the sail which ensure that the sail profile is smooth and aerodynamic.