A gennaker is an Assymetric Spinnaker (gen[oa-spinn]aker). Laser introduced one in 1998 for the Dart 18, but it did not take off. It was quite small and dropped into a chute on the trampoline. It was not accepted in the UK, but, in Ireland, my son won the Open championships in 1998 and the Cong-Galway passage race in 1999, using this gennaker, against Hurricane 5.9s, Hawks and standard Dart 18s.