...need to learn how to enclose photos...

FWIW - We did head and foot measurements today when we compared our Goodall F 16 mainsail with our new Schurr main.

The Goodall came out at 36.5" by 81" @ 45% of the foot length.

The Schurr came out at 47.12" by 80.75" @ 58% of the foot length.

ACat230's performance range, for sails competitive in A Cats, was cited at 44% - 52% or thereabouts.

Bottom Line.... according to explanations from Carl Reigart, USSA Portsmouth Chair and Dave Ingram, the head modifications are not subject to PN modifiers in accordance with the Rules for Portsmouth Racing, which are Class dependent. Class Rules are transcendent and not under regulation by the USSA PNY Comm. 'Box Rule' Classes must only maintain the same sail area to avoid a ML assignment (MN n/a). The International F 16 Class 'Box Rule' does not restrict head design or leech design.

ACat 230 was correct when he claimed that high aspects are unproven according to recent users.

I wonder what the head to foot ratio is on an AC 45 or Extreme 40. Thank Goodness we are not limited in our imaginations by backstays.

I stand to be corrected in order to become more enlightened.

Sail in Peace,
Bert