Thanks, but please don't take my statement as an accusation - just confusion. It is entirely possible that the sources I used include mast area and I didn't realize it.

On another note, I performed the following thought experiment: I removed the 3.72 m2 jib and added a 17.5 m2 spinnaker. The rating changed from 1.050 to 1.108. That's right, I added nearly 14 square meters of sail and the boat got 5.5% SLOWER! I could cut 1.72 m2 off my jib (leaving a 2 m2 blade), add a 15.5 m2 spinnaker, and wind up with the same rating. Apparently SCHRS calculates that jib area is 9 times as valuable as spinnaker area. If that's true, why are boats bothering with spinnakers?

I noticed another oddity - when jib size gets too small (under 1.4 m2 in my experiments), the rating shows the boat getting faster. That's probably just a pathological case, since nobody would design such a jib, but it is still confusing.

Also, why does a low-aspect (height-to-width ratio less than 1.5 : 1) boom count as mainsail area, but a high-aspect boom (greater then 1.5 : 1 ratio) doesn't?

Yours in puzzlement,
Eric