Wouter,

The Australian NACRA 17 was designed as a sloop. The Inter 17 development team in the U. S. started with those hulls, lengthened them 5" to reduce the rocker, and then developed the rig as a spinnaker rigged single-hander. The hulls and rig for the two boats are different. The I-17R was a result of the Michigan fleet saying to the dealer that we would buy the boats if it had carbon mast and sail area comparable to the NACRA 5.5 Uni. Ultimately, the development team decided that 170 Sq. Ft. mainsail was too large and reduced it to 165 Sq. Ft. The Michigan fleet specified carbon mast, high-tech sail cloth and spinnaker. The factory left the spinnaker as an option for the I-17 and I-17R, but I think the new F17 comes with spinnaker standard.