I don't know how your club operates but in the clubs I have been inolved in in the UK, all members have to help out and do duties. That inlcudes those that sail only 5 times a year.
It is the same at our club and the other one I was a member of. However, these people just show up to a prearranged schedule and do their duty. The guys and gal organising the whole shabang, making the schedules, preparing the work etc are still mainly those 15 % of the whole group.
Wouter
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands