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      Abbreviated rules   07/28/2017

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atg

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About atg

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  1. Most excellent build. The big issue with twin main foils as I see it is induced drag at takeoff. You really want maximum span there. With two foils you get two more tip vortices than needed, and much more drag when you can least afford it. The strut drag is significant, but with two struts the main foil can be so much higher aspect that it outweighs the loss from the struts, and the struts can be much smaller also. I suspect we may see twin strut moths at some point with the Clive system if the fairing drag can be worked out.
  2. Sorry about that. That carriage was a bit of a compromise between Gaudi-esque style, reduce/reuse/recycle, and death needles.
  3. If Riou really lost some important sails just after the start, the new foiler must really be a dog to have only finished 30 miles ahead. Those foils look like they have a ton of induced drag. Avg speed was 12 knots, which is not where you want to be trying to lift a keel boat onto foils. I'd say PRB is looking quite strong for the Vendee.
  4. GA was doing 15-16 upwind at one point. Definitely foiling. I don't think they were on a reach as they were not laying the windward mark. Looks like they take off at 12 knots boat speed or thereabouts. Would have been fascinating to have a moth on the course today.
  5. On the c-class health issue, to me the AC has borrowed far more from the C-class than the c has borrowed from the AC. Hell the AC boats are getting smaller all the time; Pretty soon they will be C cats even without intervention. And with that the hegemony of the C will be complete. What took those AC guys so long to see the light?
  6. I am a but surprised others did not copy groupama more carefully at this event, in terms of design. Not to say that would be easy to do. I would be very interested to see a moth line up against Groupama around a course in say 12 knots. I think these wings are enough less draggy and better shaped that they sail a lot closer to the wind on all points of sail. Yes GA may not fack or foil gybe, but how long will that remain the case?
  7. This discussion came up in the Moth worlds thread. I'd much rather have the virtual eye style tracking than some shaky cam, we're not really sure who's winning or what's happening, "live" feed. With the digital stuff you can see the whole race course, see who's going to which side, know for sure who's who (none of this "That's X coming through for the win! Not wait it's someone else!") etc, etc. Both would be ideal, but if it's one or the other actual data wins for me every time. I'll accept it's just my opinion. Personally I get more out of a good trac trac GPS feed than anything else on the internet, with the exception of good interviews done on shore. I do wish this little AC data were available on a viewer and not just a video of a viewer, but beggars can't be choosers. Live video to me seems like the dinosaur, unless you have drones following leaders around the course and the superimposed sport vision animated laylines to go with it, it just gets a bit tiring.
  8. Opinions are like noses. The internet is a giant relief valve so people without the 3.5 large can feel like we are important, too. I matter, dammit! Kind of a genius move by Darpa, from a Marxian standpoint. There are so many more boring things to spend that kind of coin on. It takes some balls to put the details here for everyone to carp at. Say thanks and nice boat, or move on.
  9. Blunted you are correct. They spent the week testing different foil. I saw the boat coming in with a port foil that looked like the one they are using to race and a starboard one that was about a foot longer in span (uptip part). I believe they have tested 3 or 4 different foil designs... In all cases they were going blisteringly fast. Though what impressed me the most today was their gybing angles... VMG must have been insane! It's like the thing is generating it's own wind! Are they able to do foiling gybes?
  10. I don't think they use a wand-looks like uptip foils to me: http://www.norgador.com/ IMG_1851.jpg Here's a pic of them sailing today. it's like a moth, controlled by two wands and I suspect that the entire foil moves. Yes that's correct they have a very long wand (i guess to générateur enough hinge moment) to move the entité foil AoA. I think they also have a setup so that when they lift the windward foil, the want gets held in the il position so as to not create any drag. According to Jean-Pierre (helm), foiling upwind was very easy today but downwind they were struggling... My intuition (without looking at it in détails or putting too much thought into it) is that at higher speed the système is struggling and the réponse time is too low to work. I have heard some comment as well saying at times the wand gets submerged or creates enough of a wake that it doesn't feel the ride height well enough. Hard to tell really! Yes one has to think that system through very carefully to keep the wand loading (and drag) down. Foiling upwind is always easy, because you can slow down quickly by pinching, and overall speed differences are less. Offwind is always the test. The battle is won or lost in load modeling the design and in executing it with very little friction.
  11. Depends on conditions probably. Having a gennaker for light air must be fast. One of the advantages of the C must be weight however. Smaller foils, less crew, virtuous design cycle, etc. Probably more foil iterations than a 45F also, and potentially better control system. If 19 is upwind then they are certainly foiling up and down. I only saw 12-14 in the first race though.
  12. It would be kind of sad if a team of professional full time sailors and designers could not show up at an otherwise non-corporate event and clean up all the hardware. It must be a bit depressing when they mention how many different sets of foils they have tried and how much they have learned. Looks like they are canting the foils outward to give the lifting portion more windward bite. This is fundamentally unstable, but they either pinch or have some way to control it upwind. They are doing 12-14kts upwind I saw at one point. The angle looks impressive also. Downwind they were 28 plus. Impressive stuff.
  13. OK starting line is being set. Windward mark being set
  14. Scheduled start is now. Doesn't look like they are lining up yet though; everybody ripping around the course on the live feed. Is there a twitter feed anywhere?
  15. Yes the length of those foils would seem to be great for twisting the entire hull off of the beams. No surprise about the springiness; getting that stiff without being heavy means the heads have to be pretty fancy on those boards (not to mention the hulls, beams and deck to beam joints). You essentially have a huge clothespin type affair athwartships with a sliding angle adjustment at the most highly loaded part. Bold move. Bon chance with everything and thanks for the updates!