I missed the waterline statement. That is a good start.

But, now we need a definition of the measurement trim for determining the waterline because waterline is a defined term in the ERS. Should the sails be on the boat? If so, where should they be? Should the mast be on the boat? If so, how much rake should it have? Since it flies a hull most of the time, should it be measured in hull flying position?

This needs to be a very exact measurement because the hulls are not very wide or deep. An error of 1 cm could probably allow the foils to be canted 20 degrees. The symmetry rule needs to have tolerances defined.

If a hull is canted, the waterline is not perpendicular to the the hull's plane of symmetry. So, does that mean that the side of the hull that is deeper in the water (inside of an infusion hull) can be symmetrical with part of the hull above the waterline?

Do we really want builders to be able to do whatever they want above the waterline? What if the port and starboard hull shells nearly came together in the middle? I have wanted to do this on my boat to make an aerodynamic fairing for the beams. But, the rules were not clear if this would be allowed. If we allow asymmetry above the waterline, this would clearly be allowed.

I'd also like to point out that this is a fundamental rule change. Boats never used to need to be symmetrical below the waterline. If we want to change the rule, we should do some with a great deal of contemplation or not do it at all.