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      Abbreviated rules   07/28/2017

      Underdawg did an excellent job of explaining the rules.  Here's the simplified version: Don't insinuate Pedo.  Warning and or timeout for a first offense.  PermaFlick for any subsequent offenses Don't out members.  See above for penalties.  Caveat:  if you have ever used your own real name or personal information here on the forums since, like, ever - it doesn't count and you are fair game. If you see spam posts, report it to the mods.  We do not hang out in every thread 24/7 If you see any of the above, report it to the mods by hitting the Report button in the offending post.   We do not take action for foul language, off-subject content, or abusive behavior unless it escalates to persistent stalking.  There may be times that we might warn someone or flick someone for something particularly egregious.  There is no standard, we will know it when we see it.  If you continually report things that do not fall into rules #1 or 2 above, you may very well get a timeout yourself for annoying the Mods with repeated whining.  Use your best judgement. Warnings, timeouts, suspensions and flicks are arbitrary and capricious.  Deal with it.  Welcome to anarchy.   If you are a newbie, there are unwritten rules to adhere to.  They will be explained to you soon enough.  

flutter

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  1. Gitana Maxi 17

    I think cavitation erosion is pretty well documented in the 40-50 knot range. I dont think Moths or kitefoilers ever really see those speeds?, but certainly on a boat like this it would be a consideration. Would be cool to see pics of what the result looks like - ie from the AC - expect to see some kind of patterned pitting on the surface similar to this?
  2. Gitana Maxi 17

    They have gone to a fair amount of trouble to build this boat, I'm sure they are on it!
  3. Gitana Maxi 17

    I find this image super interesting, thanks for posting! Yeah that foam looks like it's just a fairing behind the main spar, i would be surprised if it would make much difference whether that area was monolithic or not due to how thin it is relative to the rest of the section. The principle behind the structure seems to make sense, and im sure the laminate is as designed. I imagine that the loads in big waves could be fairly hard to predict and would be right up there when the hull crashes down and the foil slaps on the water at like 30 degrees AOA. Seb's report that the lift was gone, even negative lift making the boat feel heavy.. suggests in my mind that the spar is de-laminated and the tip section of the foil is twisting off under load. And all that damage could just be the skin shitting itself as the spar flaps around under water. I guess when you design these things, you're always trying to make them thinner for drag but thicker for structure - for a given structural system. So hard to find that ideal balance. I'm sure the BP design team are looking at this carefully also, I wonder if this suggests that everyone's assumptions about max loads need to be updated?
  4. Exclusive Interview with PETER BURLING

    for anyone who may have missed this - this thread made me think of it somehow!
  5. Vendee Globe 2016?

    you can watch this in VR with a google cardboard viewer + iphone / android and the youtube app. i hope theres more content like this!
  6. New imoca boats

    requires a pretty good pivot point! + like T foil rudders, they would be trouble to raise and lower at speed + you drag both the lifting and side force surfaces around whether foiling or not anyway.. what do you reckon the advantages are over the current setup? - that you get a more efficient daggerboard for upwind sailing etc?
  7. ha yep! we have not seen anything like that before! waste of materials and massive environmental impact etc. but.. definitely not like anything else..
  8. Artemis?

    Sarah Gundersen!
  9. Artemis?

    Your description of the structure would be accurate IF the bowsprit was a beam .. but it is NOT a beam .. The loads applied by the headsails are supported by the rigging while the bowsprit supports the eccentricity as a column . Round tubes are the most efficient shape for a column and this only changes if a bending moment is applied or if the member is required to serve some other purpose such as a walkway .. The triangular shape might also help in a pitchpole situation . Its not a column either. i.e there are no stays that support the tip horizontally. EDIT: ahh, maybe there are... ok you might be right. In a pitchpole, think about it. what is that angle of attack of that flat top surface to the water? -5 degrees? it will only help you go over faster. hence why the hulls are pointy on the top. Maybe its for spray / waves when sailing normally, or, as you say, a flat walkway
  10. Artemis?

    smaller section size doesn't necessarily make a lighter tube. Wall thickness decreases as diameter increases, so there's a crossover point somewhere, I'm sure each team is pretty tuned in to that and have optimised their tube sections for the specific loads and target stiffness. The triangular section I imagine is stiffer in the important directions than a round tube of similar weight. The load at the front will most likely be similar to the other boats, though with a thinner 'egg shell' wall might, counter intuitively, make the tube a bit more fragile.