The primary purpose of this offwind sail investigation was to better understand the relative performance of symmetric spinnakers flown from conventional poles and asymmetric spinnakers flown from conventional poles or sprits, i.e. poles restricted to the centerline.
The specific goal was to improve the aerodynamic modeling of offwind sails used in the International Measurement System (IMS) handicapping formula to address perceived inequities in their performance potential, particularly when running at very deep angles.
Running style offwind sails of varying size, type, and pole configuration were evaluated over appropriate ranges of angle of attack and trim settings. Improved performance coefficients were developed from this data for inclusion into the 2001 IMS velocity prediction program.