RobG

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Everything posted by RobG

  1. RobG

    trickle down

    If you're talking about power boats, it seems the costs don't stack up. There were a lot of hydrofoil ferries around the world in the 60s through to the 90s, but not many now. Sydney Harbour had hydrofoil ferries from 1965 to 1991 when they were replaced with high speed cats. There was also a lot of work on hydrofoiling navy vessels, probably dating back to the 1940s, how many are in service now? From anecdotal evidence, US nuclear powered aircraft carriers can do well over 40kn, that's around 100,000 tons going the same speed as an AC50 downwind. Why complicate things with hydrofoils? :-)
  2. RobG

    trickle down

    My original post was immediately below: I didn't quote it as I thought adjacency was sufficient context.
  3. RobG

    trickle down

    Certainly that was innovative for a multihull (retractable foil systems were being used on monos well before then), but somewhat obvious when you have crew to do the job and class constraints that stop the windward foil from being useful, like creating downforce. I'm not arguing that the ETNZ AC72 wasn't very innovative and a big step forward for flap–less foiling multis—they certainly proved that where the As were heading worked—it's just that I don't think it was singlehandedly responsible for the recent increase in foiling multihull designs, some of which use entirely different foiling systems. I think it can be put down to the overall increase in the adoption of foils on many craft, including surfboards, sailboards, kites, even canoes, mostly driven by advances in materials, lowering of costs and the appeal of higher speeds through efficiency rather than brute force.
  4. RobG

    trickle down

    I would say the AC was just part of the trend. Certainly ETNZ's foils were a big step forward, but really it was just an evolution in the development of non–T foils. The A Class was playing with curved foils long before AC34, but the "insert from below" rule (introduced in 2009) was a pretty obvious attempt at stopping them from developing ETNZ–like L or J foils.
  5. RobG

    AC 36 Protocol

    Not sure what to call an event that costs $100m plus to play the game, has strict nationality clauses and the diversity of banker's club, but "inclusive" it isn't.
  6. RobG

    What Not to do on a Dinghy

    A German IP address gives: A Singapore address worked fine. Why do supposedly clever IT people think public IP address has anything to do with where a client device is actually located?
  7. RobG

    New imoca boats

    What is it about "While I concede that the leading edge is angled up…" that represents "fake news"? The Seahorse Magazine article is a good reference, thank you.
  8. RobG

    New imoca boats

    While I concede that the leading edge is angled up, I'd be very cautious about using an uncontrolled oblique image as proof. Without access to appropriate photogrammetric equipment or very sophisticated digital technology, to show an angle of 5° or 6° accurately in an image, you'd need to align the camera, keel and boat carefully and identify some datum for horizontal, such as waterline or similar. E.g. in the image, the trailing edge of the axle appears to be almost twice the distance from the bottom of the nacelle as the leading edge.
  9. RobG

    AC36 CLASS RULE

    How so, given rule 27.1 says "The FCS cannot be modified except as expressly permitted in the supplied specification.". Have you seen the FCS specification, or know what's in it?
  10. RobG

    New imoca boats

    Limiting cant would also reduce keel AoA and hence lift, so maybe it's not as helpful as the designers thought.
  11. RobG

    New imoca boats

    No. If "declined" is down toward the bow, then "declined" it is. As I understand it, the axis is inclined to produce a negative AoA on the strut when canted. Since the keel is canted to windward, you don't want lift acting against the weight of the ballast, but rather a small negative AoA to enhance it and generate more RM. At least that's the theory.
  12. RobG

    Teams?

    Calling out racial prejudice for a perfectly valid assumption is bullshit, "bud". The initial statement was:
  13. So excess righting moment caused the boat not to self–right? Hmmm…
  14. Be careful of artefacts in these images, e.g. the splash screen for the INEOS promo video has this image: I think the curves are in the video, not the real foil.
  15. RobG

    shit show (front page)

    Yes, I came to that conclusion too and nearly deleted the post. Maybe a case of trickle up? The joys of skiff sailing being introduced to what used to be lead mines? :-)
  16. RobG

    shit show (front page)

    In the new video, (if it's the same incident, the clip doesn't show the boat capsizing), it looks like the starboard foil ventilates a la Moth, with the same result: down the mine they go. I think the image below is the first one in the clip, pity they didn't include a bit more of the prelude and aftermath as there's a lot of spray from the rudder too. It would be interesting to know which came first. If the rudder snapped, there should be nothing from the back of the boat. Perhaps they're just too high and both rudder and main foil are ventilating? It's pretty flat water, so good time to see just how far they can push it. The port foil seems to have much more anhedral, perhaps to avoid such severe ventilation?
  17. The INEOS boat doesn't have full articulation of the arms, hence the inflatable stabilisers. Also, they may not have sufficient ballast to provide suitable low-speed RM even if they could go fully down. And there's always the chance that the arms get stuck in an unstable configuration, or just can't get there fast enough. It seems to me if you depend on a foil for RM, as soon as it stalls, ventilates or cavitates, the lift is gone and the whole stability equation goes to shit. Quickly. The arms will need to be able to adopt the high–stability configuration very quickly and extremely reliably (without crushing or slicing someone in the process).
  18. RobG

    New imoca boats

    Why no T foils on the rudders? It would help to further reduce pitching, keep the bows up and reduce the (often huge amounts of) water coming over the bow. The big tris use them, why not the monos?
  19. RobG

    The new sailing twin skin setup

    There is a significant caveat though that the sail is under enormous stress at the time. Determination of reverse camber requires calculation of some datum of zero camber (with respect to the apparent wind? lift vector analysis?…?), which is likely not aligned with the boom. Also, 3D calculations or interpretations from a single, off–axis 2D image are likely to be imprecise, and being taken from a long lens quite some distance away can lead to misleading artefacts. So I'd be cautious in using the image as conclusive proof of reverse camber, it might just be the effect of the massive deceleration of the rig and change in apparent wind on a typically twisted sail—the energy has to go somewhere, so the head is going to fall off to one side or the other, and probably favour going to leeward. But it certainly looks like reverse camber. ;-)
  20. RobG

    Teams?

    Great, so we can agree that it doesn't matter whether you break the rules on or off the field, it can still be called cheating. I quite specifically referred to cheating as deliberate fouls to gain an advantage, which includes so–called "professional fouls", which is a (hopefully small) subset of "every competitor who has ever been penalised". So we agree on that. However, it's you who are continuing to call OTUSA cheats for a single breach of a rule and to call into question the result of a completely separate competition. That is akin to me calling McCaw a cheat forever more because of a single foul widely recognised as cheating. It probably won't stop me calling Lance Armstrong a cheat in perpetuity. Yes, OTUSA could be called cheats for the "lead in the king post" incident in the context of the AC45 ACWS. But to continue to call every team called OTUSA cheats forever more is, in your words, "plain stupid".
  21. RobG

    Teams?

    I could respond with Hitchens's razor, but will elaborate. Because there are differences in the details of two things being compared, it does not necessarily follow they're not sufficiently equivalent for the purpose of the discussion. Apparently mfluder thinks cheating can only happen through actions taken off the field. Tell that to golfers accused of promoting their ball out of the rough and onto the fairway, or cricketers who polish the ball with vaseline instead of spit, or roughen it with a thumbnail. The point of using other sports is that it provides a much larger context than the comparatively tiny realm of competitive sailing. It also shows how such a narrow definition can't be sustained when applied more generally. So if OTUSA is to be forevermore called a cheat, then so must McCaw (and yes, the thousands of others across many sports who commit "professional fouls"). And attempting to extrapolate that cheating in one game has somehow affected the outcome of a following, entirely different game, defies logic.
  22. RobG

    Teams?

    Your claim of false equivalency is an example of false equivalency.
  23. RobG

    Teams?

    I have never said, here or elsewhere, that OTUSA didn't cheat. So if they'd added and removed the lead while on the water, that would be "while competing" and so OK? Probably not. I think your point is about intention, and certainly agree that deliberately breaking the rules, sometimes called a "professional foul", is cheating. A player of McCaw's experience would know at least 90% of the time that they were about to break the rules, but he did it anyway. A lot. So he's a cheat by your own definition.
  24. RobG

    Teams?

    So now we know where you stand: cheating is OK as long as the perpetrator get's away with it more often than not. For all you know, that might be the cause with OTUSA. In fact, since they were only caught once and McCaw was caught often (just not as often as some would like), they might even have a better cheat/pentalty ratio. So maybe you should be singing their praises rather than relentlessly banging on about an irrelevance.
  25. RobG

    Teams?

    I guess if you met Richie McCaw you'd refuse to shake his hand. Maybe you excuse his his cheating because he usually got away with it.