Tom,
On my A-Class, I was first to the weather mark in 3 out of 4 races (it would have been 4 out of 4 but I thought I was over early in the second race and went back and re-started, I was still 3rd to the weather mark). In the light air we had (1-6 knots) I'd get killed downwind by all the boats with the chutes as everyone there was pretty competent. But then upwind I'd nearly catch most of the boats that passed me downwind. In two races, Curry passed me downwind and then I passed him again upwind. There is a US Sailing course that has an upwind finish so it might have been interesting if we had done a race with three upwind legs (LOL)! My point is that I believe the F-17 should really rate right below what the A-Class currently is (around 64.6) or close to the F-16. I asked Bob about this and even he agreed that he is sailing the boat faster than its current rating. It's quite a challenge racing against the spinnaker boats with the A-Class. You have to sail defensively downwind to try to minimize your losses as boats roll up on you and then try to close the gap again upwind. I've never raced an Open Portsmouth regatta like this in fully powered conditions where I can fly a hull downwind. I'd like to do that.
Bob Hodges
My experience in sailing an F16 many times against fleets of 5-7 A-cats is that the F16 has a huge advantage downwind up until the As can go wild downwind. I still found the As tough to beat across the line around the full course since they're so fast upwind; but the current handicap put me right in the mix. Once the As can fly a hull downwind, the advantage of the spinnaker is dramatically less and the As become very hard to beat, even on handicap.
Incidentally, I find the current nacra 17 number hard to believe and is probably simply because there isn't much mixed fleet data for the boat.