J/70J/70 is a trailerable, American sailboat class designed by Alan Johnstone and first built in 2012.WWW jboats.com/j70-one-design...ProductionThe boat is built for J Boats by three builders, CCF Composites in the United States, J/Composites in Europe and J/Boats Argentina in South America. At least 1451 had been constructed by 2019.DesignThe J/70 is a small racing keelboat, built predominantly of fiberglass. It has a fractional sloop rig, a transom-hung rudder, a retractable bowsprit and a lifting keel. It displaces and carries of lead ballast. The boat features a very large asymmetrical spinnaker with an area of, flown from the carbon fiber bowsprit.