Shu

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107 F'n Saint

About Shu

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  1. Shu

    New Corsair 880

    I have heard that a couple of these have made it to the United States. Has anyone here sailed one yet? Also, I haven't seen any photos of the interior, does anyone have some they could share?
  2. Shu

    Guests realistic expectations

    So now you have what, a Tartan 36?
  3. Shu

    In Production: Spirit 111

    The design brief was for it to be sailed without professional crew. Part of the reason that keel looks stubby is that it has a long chord length. It may not be a particularly efficient keel shape, but it will be hard to stall, which should be good for non-professional (read less experienced) sailors.
  4. What horrible traveler-related accident did this owner experience that led him to vow, "never again!".
  5. Cruising classes in certain races allow use of the engine. I think there is some sort of formula for the amount of use.
  6. Shu

    Rudders and roundup

    It would be nice if the prospective buyer doesn't experience a round up during the test sail, so fixing the problem is still important.
  7. Shu

    Rudders and roundup

    As a sketch approximating the shape of the real graph provided by Climenuts, I would say it was true on this planet. Closer to a flat plate though, which has the apex of the lift curve around 10 degrees AOA, not 4 degrees. Also, the drag curve inflection should be in the vicinity of the lift curve apex. It's a sketch, not an engineering figure from which you extract design information. Have you never done a quick sketch to illustrate a principle? Why am I defending 10th tonner, anyway?
  8. Shu

    Rudders and roundup

    OK. Shiny tape made me think whiteboard. Spelling of rutter is an old SA tradition. I think it goes back to the Flying Hawaiian thread. I never found the original source. Thanks for the proper chart, btw.
  9. Shu

    Rudders and roundup

    "Save some trees next time and just google an chart that's actually accurate?" I didn't know white boards and markers were made from trees.
  10. I would not be disappointed if the wheel option went away.
  11. Shu

    Rudders and roundup

    Good diagram, 10th. There have been a lot of general statements here about neutral vs. weather helm and drag vs. lift that are over simplified. Without getting too complex, I will attempt a more complete description. I'm sure Bob and others could be more precise. First, most spade rudders have some balance built in, wherein there is some area forward of the rudder stock to help balance the force of the rest of the rudder. This reduces the helm force transmitted to the helmsman. The goal is not to completely cancel this felt force, but to make it more manageable. Some rudders that are transom hung, and some with partial skegs can also have some balance built in. When the boat is trimmed so that is perfectly balanced, relative to the keel and the immersed hull, there will be no load on the rudder, only the minimum drag required to move the rudder through the water at it's most efficient, zero degree angle of attack with the flow. All the leeway resistance is accomplished by the keel and the hull. But since we have a keel and a rudder always dragging through the water, why not design them as a system? You could provide some of the lift with the rudder, and reduce the load on the keel and it's required angle of attack otherwise known as leeway. A good rudder foil section will have very low drag at small angles of attack, nearly the same as when it has zero angle of attack.. Look closely at 10th's lift and drag diagram above for an angle of 1 to 3, maybe even 4 degrees. I've heard this low angle, low drag range as the "drag bucket", which is what the drag curve looks like if the diagram shows both positive and negative rudder angles. We can get some lift from the rudder with very little extra drag. So, with the rudder providing some of the lift, it will be loaded. If the rudder is partially balanced, or not balanced at all, there will be resistance, or weather helm, felt by the helmsman. If the rudder and keel have the same angle of attack, the rudder and tiller will be aligned with the centerline of hull. There may be situations where having a slightly larger angle of attack by the rudder provides a better overall (hull, keel, rudder) lift to drag ratio, and this is where a bit of angle can be seen in the rudder and tiller relative to the centerline. Then there is lee helm. Here the boat is unbalanced so that it wants to turn to leeward. Think about sailing with the jib only. To keep the boat tracking straight, the rudder must have a negative angle of attack, the tiller is below the centerline, and the load the flow is exerting on the rudder is pushing to leeward, increasing the load that the keel and hull must take to resist leeway. The result is more drag on the keel and hull, and more leeway.
  12. Shu

    After Ericson 35...Ed will get?

    I think we can look at the pattern. He will get another boat after the Ericsson 35, either a 7ksb or a 4ksb, then he will get another FT10.
  13. Shu

    Rudders and roundup

    20-30 degrees is a ludicrous amount of rudder angle. I think that amount would be enough for the rudder to stall even if it is not ventilating. I guess at that point something went wrong when you only had a little bit of rudder angle, but then you start chasing the problem with more rudder angle until the whole thing just drags through the water and becomes useless. You mentioned that the mast had some rake. Try standing the mast straight up and see if you get anywhere. the JSO 35 is a nice looking boat, and we liked everything about it except its sailing characteristics in decent breeze. I hope you find a solution. It will probably need to be a combination of solutions, such as deeper rudder (maybe with a fence), less mast rake, reefing early (main first), etc. On boats with a tiller, I could get a chance at correcting a round up by putting the rudder briefly back to centerline in hope of re-attaching the flow, but I'm not sure you can react that quickly with a wheel.
  14. Shu

    Rudders and roundup

    I chartered a Sun Odyssey 35 about 15 years ago, and it was ridiculous about rounding up. I'm sure the blown out charter sails did not help, but it would round up even with a double-reefed main and full genoa from a broad reach. I suspect the wide stern, when heeled or lifted by a wave, would just lever enough of the rudder out of the water for it to suck air and lose effectiveness. If it were my boat I would play around with mast rake, decent sails, etc., but given the severity of the problem, I think it was inherent in the design. The OP talks about 30-degrees of rudder angle -- how does he know it's 30 degrees if it has a wheel? or is it 30 degrees of wheel rotation? I don't recall extreme angles for the rudder, the helm would start loading up as the boat started to round up, and then it just gave up.
  15. Shu

    Night Runner is on the market

    All references to LFH and other proponents of white-painted topsides aside, Night Runner is by definition a bright-finished boat. The very first thing I thought of when I read the title of this thread was that beautiful clear-finished wood cleaving through the water, and I have only drooled over her from afar. For those who have watched her grace their waters for the past few decades, I can only imagine "paint her topsides white" are fighting words.