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carcrash

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About carcrash

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    http://www.Westlawn.org
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    Cabrillo Beach YC, Waikiki YC, Transpac YC, Grenada YC, LA, NY, and Maine

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  1. The JetFoils don't kill people wholesale because they fly very high, so the wave height they can tolerate before ventilation is high. Still, exceed the limit, and watch out, as with any hydrofoil. Also, many hydrofoil accidents are related to other aspects of control, including the very large turning circle at speed, and the general difficulty in changing velocity up or down. Its not just wave height, but all 18 degrees of freedom (DOF): x, y, z, rotations around x, y, z, their derivatives, and their second derivatives. The linkages between each is non-trivial (non-linear, and stateful, t
  2. https://gcaptain.com/high-speed-hydrofoil-ferry-hits-whale-in-japan/ https://www.theguardian.com/world/2015/oct/26/macau-high-speed-ferry-accident-off-hong-kong-injures-more-than-120 https://www.theguardian.com/world/2013/nov/29/hong-kong-ferry-crashes-injured-macau http://www.histarmar.com.ar/InfGral/Hidroalas/High Speed Crash of the Hydrofoil FRESH-1.htm https://www.khi.co.jp/corp/kjps/english/emini/emini4.html
  3. The problem with hydrofoils had not changed since the very first attempts over a hundred years ago: control in a seaway. The first successful hydrofoils flew on lakes in very smooth conditions. After a century of investment by the US Navy, there are exactly zero operational hydrofoils. The reason has always been the same: a very limited sea state can be handled, and then the vessel crashes with grave danger and often injuries to the crew. All existing hydrofoils exhibit the same problem: once you exit the "safe zone" aka flight control envelope, things immediately go pear shaped
  4. Most everything @Foolish wrote is good advice, except for one thing. For certain: you want the luff and hanks all together, and the first thing outa the bag. With a sausage bag (of course), you drag the sail on deck, in the bag, open just the forward end, and hank the new sail on. As everyone mentions, set it up so the new sail is to leeward so it will help keep the old sail on the foredeck. Often, you will need to disconnect the lowest hank or three on the old sail. Attach all the hanks from the new sail BEFORE dropping the old sail. Shorthanded (this forum), heading up to
  5. Mathematically, this is a very silly thing to do with exactly on exception: if the prop diameter is strictly constrained, such as being installed in a tunnel. Mathematically this makes no sense at all, because the diameter factor for prop effectiveness is the 5th power! Diameter is king. That is why windmills are enormous: the bigger the MUCH better.
  6. Foilers MUST HAVE active control systems that can safely deal with the boat becoming airborne and re-entering with minimal accelerations. This is non-trivial. Weight is also very critical for hydrofoils, so anchors, dinghies, cocktail bars, hot guests, and so on just don't combine well with hydrofoils. There are reasons the US Navy, after investing in hydrofoils literally from the very beginning more than a century ago, has exactly zero operational hydrofoils. If the US Defense Department can't afford to make them work...
  7. A 240mm seems more appropriate than their normal size. I am amazed that the diameter of the normal propellor is so small. I would love to see repeatable experimental data that led to the tiny propellor. In wind farms and water current turbines, size really, REALLY matters. The non-dimensional power coefficient for a propellor is Cp = HP/(fluid density * RPM^3 * diameter^5). So energy generated by a hydro generator is related to the FIFTH POWER of the diameter, and only the third power (still a lot!!) of RPM. Hence, a much larger prop can spin much slower and generate far more en
  8. Wow. WS seems to actually mean "Whatta Scam!!" WS is literally bankrupt. Time for a new body, as this body has been murdered.
  9. CFD is a great way to generate pretty pictures! Getting the calibration between reality and the simulation is a LOT OF NON-TRIVIAL WORK!! If it is not calibrated, then it is certainly, absolutely wrong. CFD helps to design the experiments, but is worse than a waste of time if those experiments are not done.
  10. This was the 2.2oz star cut, made by Hard Sails. Remember their slogan: Sail with a Hard on! Other than the star cut and the radial head runner, all the sails were made by Watts.
  11. This is when we just arrived in St Georges, Grenada, just before Christmas 1976. I'm doing tug boat duties in the dinghy.
  12. The second owner of Blackfin, let's call him Jefferson Grundstueck, sold Blackfin in late 1977 or early 1978. JG told me this story of the third owner. Note that JG was not a direct witness to this story, so this story is at least X -> JG -> me. Not admissible in a court of law. The third owner, who we can call XYZ, was a drug dealer living in an apartment building in Manhattan. One day, as always eventually happens, the police came to bust XYZ in his apartment. XYZ, knowing this was inevitable, had an escape plan set to go: XYZ had an escape chute: a ten story chute, similar to the
  13. There are people and things that have had an enormous impact on my life. Blackfin was perhaps the most significant thing. Without Blackfin, I would not have any of my children. I would never have met my wife, Lisa. Those of you who know, understand that statement! During the Transpac 75 trophy presentation, I met Leslie DeMeuse. Visiting the DeMeuse home, I first got to know Blackfin. A year later, the boat was sold, and I was brought aboard to deliver Blackfin to England, teaching the owner how to sail as we went. On New Years Day 1977, I set the record around Grenada, beating @P_Wop in
  14. I am very glad I removed my headsail furler, and went with soft hanks. The hank-on jib has full battens, which of course is a huge win. The hank-on jib has dramatically less windage when not hoisted, so the boat lays at anchor nicely without tacking and pulling the anchor out of the bottom. Dropping the jib is certainly easier than un-rolling a jib on a furler (assisted by the full battens). Hoisting the jib is much, MUCH easier than rolling the jib on the furler. Since the sail is not being stretched to hell and gone by a furler, the sail is made from high quality cloth, so the shape is
  15. I just made cleats glued to the inside of the hull, and then had them down with dyneema lashing. Easy, light. You don't need a box like with lead acid: no outgassing, no acid, nothing to leak.
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