Doug Halsey

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About Doug Halsey

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  1. Doug Halsey

    Thistle repair questions

    Here's a scene from Alamitos Bay (Long Beach), taken in about 1973. Could that be the same 5.5? (There couldn't have been that many, right?)
  2. Doug Halsey

    Physics of sail power.

    At least one of those (Einstein) was a sailor. I'm not sure how great though. Albert Einstein, Sailor - National Maritime Historical Society (
  3. Doug Halsey

    Dean is American and Jimmy Italian??

    They were around a little before the 50's (not quite competitive though). Robert Gilruth: The First Foiling Catamaran-1938 | Foiling Week™
  4. I was trying to explain what would happen to the board's load if you tried to make the flow on the hull symmetrical. Even with zero leeway, the load on the board would cause some asymmetry in the flow over the hull.
  5. Everybody here seems to be assuming that it would be optimal to have the hull going straight through the water, but that isn't true. If you did manage to achieve that situation, the daggerboard would have a very unfavorable spanwise loading that tapered to very small values at the intersection with the hull, with extra twist drag, and higher loadings down low, causing earlier stall. The smallest drag would occur with a much smaller amount of asymmetry than required to get the hull going straight. An analogous situation occurs in determining the optimum loading of a fuselage in a wing-fuselage combination, which never works out to exactly zero.
  6. If you have the option to use asymmetric boards, the question is how much asymmetry you need, rather than whether it should be symmetric versus asymmetric. The answer to that depends on what CL you are trying to optimize for, and what extremes you are allowing for. Here are some calculations to start you thinking about that.
  7. Doug Halsey

    Bicycle with a sail

    If you're interested in landsailing, check out NALSA home
  8. Doug Halsey

    18ft Skiff Cuff Luff

    Moths had sleeve-luff sails before cams were invented. (I'm not saying it was ideal though). Here's mine in 1968 (sail by Australian Garry Fogg)
  9. Doug Halsey

    A trimaran daysailer foraging boomers

    I've been on the verge of posting something like this, but have managed to resist the temptation. But it raises the question: Is it possible for someone to edit their earlier posts? Seems like it would be a good idea.
  10. Doug Halsey

    best new foiler for beginner?

    There are Moths & A Cats (& a few others) in Southern California. You might consider joining the West Coast Moth FB group.
  11. Maybe it stands for "Fiberglass" & he's wants a fragile boat that requires a lot of repairing.
  12. What does "FG" stand for? All I can think of is "Field Goal."
  13. Doug Halsey

    Craigslist Finds

    These 2 photos from that listing can't be the same boat, can they?
  14. Doug Halsey

    Craigslist Finds

    I have a nice Bruder OK Dinghy mast (almost 50 years old now!) I might still use it for something though. Probably too small for what you want anyway. Plus thousands of miles away.
  15. Doug Halsey

    Multihull speed vs length

    I agree. I've sailed my 15' foiling trimaran a bunch of times without the foils, and the top speed for the day has almost always been ~14 1/2 knots. Never over 15.