There has been lots of English-speaking, boat-owning and boat-building wrangling over the vertical plane wording. Nobody's ever come up with a better phrasing than we have. Take a whack at it?
Without giving it much thought -
"Vertical plane shall be defined as the z axis of the boat parallel to the direction of the mast (insert diagram here)."
Not that hard I would have thought - or am I missing something?
Michael
You are missing that the Infusion (and the Cap, I think) would be non-compliant, as the hulls are canted.
Go back to my original. It works for all the boats, whereas the ERS ISAF description is innappropriate for a catamaran of two individual hulls (that may or may not be canted).
Flashy geometry language could be substituted for the part in question, (i.e. 'daggger boards and rudders will be at 90 degrees to the angle of attachment to the beams') could become ''daggger boards and rudders and the center plane shall be orthogonal (90 degrees) to the beam seating angle of the individual hulls' but my opinion is that simple language has advantages to acceptance and recall of rules, (vs jargon which is sometimes unintelligible).
Oh, and skip water line discussions. While there may be design specifications, actual water lines are unknown until a boat is floating. IMHO a waterline is an arbitrary, and empirical specification, and therefore a non-starter from a rules standpoint.
