Hi Scooby,
... It is "The space a boat needs in the existing conditions while manoeuvring PROMPTLY in a seamanlike way. I emphasized the word "promptly" because that seals the deal against your devil's advocate position. You must not only respond to the luff but you must do it promptly (no excuses). You must be prepared to handle your boat promptly in a seamanlike way at all times. It is not seamanlike to capsize, shrimp the spinnaker, teabag while trapeezing, steer erratically with your foot on the tiller, etc. That may happen at times with any of us, but it is not an "out" with the rules. They explicitly state what is required and that IS something that you need to anticipate no matter what your course....
OK, but I would argue that to maneuver a spinnaker so you can sail to windward in a seamanlike way would be to drop said spinnaker...not flip the sucker.
I think this is a 50/50 proposition...maybe 60/40 in favor of the leeward non-spin boat. It's going to come down to the judge until we have an exemplified interpretation.
