Crossbow fl

Discussion in 'Sailboats' started by Doug Lord, Jun 21, 2012.

  1. Doug Lord
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    Doug Lord Flight Ready

    ======================
    Frankly, I think that is absurd: there are dozens, if not more, designs out there that require training to sail properly and which if sailed stupidly or with brain fade could result in serious consequences. This is about a prototype whose testing will address all the problems that could reasonably be expected to occur(and then some) and sharpii2's comments are important in that respect. But to say that because someone "thinks this or that may be a problem" is no reason to halt development of a potentially extraordinary boat and a whole new way to sail!
     
  2. sharpii2
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    sharpii2 Senior Member

    Training doesn't always work.

    Sometimes people freak out and just freeze.

    A better solution would be to have the wing always work automatically. kind of like Segue(r). The wing control would have a gyroscope and a sensor. If the boat started heeling to leeward beyond a few degrees, the wing would extend. If it heeled to windward the same amount, it would retract. If it heeled more than 30 degrees to leeward, the wing would retract to dead center instead of extend.

    At that point. it would jamb its leeward end into the water, causing not only a lot of leeward buoyancy but also a lot of drag. Such drag, on the lee side, would cause the boat to turn away from the wind, no matter what the skipper tried to do with the rudder.

    Such a set up would certainly make this system safer, but it still wouldn't make it completely fool proof. A greater and greater reliance would be put on automation. If the automation failed for any reason, disaster will almost certainly occur.

    In my previous post, my only goal was to show that this design could end up in an irreversible capsize.

    Having shown that, I have to wonder what this concept has that makes it much better than a trimaran with low buoyancy floats.

    The lee float could even have a foil on it that could effectively double its buoyancy, but still not be sufficient to lever the main hull out of the water. A moveable weight could be added to run the length of the cross beam, if its weight is less than half the buoyancy of either of the floats.

    Then, even if it's on the lee side, it cannot lead to, or induce a capsize by itself. It can merely cause the lee float to go under sooner.

    The connecting beams would be next to go under, creating a lot of capsize dampening drag, which would also cause the boat to turn away from the wind. This could happen much slower than with a mono with a trap wing, with a control mechanism that, for some reason, suddenly fails.

    And it would be cheaper too.
     
  3. Munter
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    Munter Amateur

    Worrying about the safety of this craft is a bit like worrying about whether or not to wear a helmet when riding a unicorn. You can do it if you like but don’t let it trouble you too much.
     
  4. Doug Lord
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    Doug Lord Flight Ready

    ----------------------------
    sharpii2, I don't agree that your previous post establishes that the boat could end up in an irreversible capsize. It wouldn't work like that.
    -----
    1) One thing I learned in sailing the models with a Power Ballast System is that having control of stability at your fingertips is a lot of fun and would allow most people to react very quickly to any scenario. One thing I might consider is an automatic device to move the wing to center and to leeward with "X" amount of heel. But I'm not convinced that is necessary. A fully automatic system is possible with todays electronics but that takes all the fun out of controlling the Power Ballast System with the joystick.
    --
    2) The wing tip is designed to create dynamic lift if it hits the water at speed-it would be vitually impossible to submerge it while moving fast. The leeward tip hitting the water at speed would cause little if any tendency for the boat to turn downwind-thats like saying a trimaran ama would cause the boat to turn downwind-just doesn't happen and I've sailed many trimarans including one where the lee ama flew most of the time. But I've also got many hours sailing a number of test models using a Trapeze Power Ballast System: the ballast system rack almost never hit the water but when it did it caused no turning moment to leeward or windward-thats just a fact.
    --
    3) Trimaran's have been used for disabled sailing-one guy sailed around the UK in a Challenger tri and capsized and righted the boat,if I remember correctly. But as much as I like trimarans I don't think the possibility of pitchpole or capsize makes a high performance tri a good boat for disabled sailing-sure with a chase boat it could (and does) work. But the Crossbow can be righted by the crew without outside assistance and I think that makes a big difference.

    Pictures,L to R-1) Super Scow with Trapeze Power Ballast System, 2)-4) Crossbow fl model and sealed wing shape:
    click then expand for best view--
     

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  5. sharpii2
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    sharpii2 Senior Member

    I think we should keep our comments within the realm of boat design principles. And leave our snide comments in the middle school locker, where they belong.

    Whether Doug's design is as safe as he thinks it is, IMHO, is a matter for reasoned debate.
     
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  6. Skyak
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    Skyak Senior Member

    Sharpii,
    I favor reasoned debate, but be honest, is anyone reasonable on Doug's side of the debate? Is it coincidence that no professionals can even look at these threads anymore?

    This is the second time I have bothered to tell Doug that in order to be worthwhile the development will have to be done to higher standards than he can appreciate -for liability reasons. And twice Doug has rejected the notion while demonstrating absolute ignorance of the law.

    A product that is a known challenge to operate but functions as advertised incurs no liability. A product that claims to make something safe but fails is liable and the standards of proof stack heavily against the manufacturer.
    Mfr claim of safety+accident=lawsuit
    plausable account of failure without proof it could not happen =treble damages + pain & suffering

    LOOK IT UP! I am sick of being treated as if I mean him harm (just because I did not shun his adversary). I would like to see this effort succeed, but at the rate it is going it won't be ready to mitigate his infirmity, let alone anyone else's. Munter's comment is only snarky to make light of the truth.
     
  7. Doug Lord
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    Doug Lord Flight Ready

    Why would I mention that training will be important if I didn't realize that a non-automatic system doesn't sail itself? With training I believe this system will be absolutely safe and I have years of model prototype sailing experience using a system very close to this one to back that up. While there maybe a feature or features that are automatic as testing is done, the fact is that sailing a system like this with direct control of the ballast is loads of FUN!
    I have some very experienced and well respected "profesionals" lined up to help me with this project including Eric Sponberg-a marine engineer and naval architect. He wouldn't waste his time with it if he thought it couldn't be done safely and provide a lot of fun for the sailor involved. Eric has helped me a lot over a long time and wouldn't hesitate to point out any weaknesses he saw in the project.
     
  8. Skyak
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    Skyak Senior Member

    Training does not mitigate liability. Operator intoxication does not even mitigate liability. You seem to still defy my point without even researching it.

    I have great confidence that Eric will enlighten you about liability, but your needs are outside his expertise (electro-mechanical systems). First you make a proof of concept craft -then you can talk to the professionals about production intent and validation...From what I know I would think that the electro-mechanical control guy would be the lead and do the DFMEA so Eric could just speak to the boat needs and behavior. If you could get a guy that had done a handicap vehicle I think you would be in good hands. If Eric wants to talk about it I always enjoy discussing things with him and could consider my warnings heard.
     
  9. Doug Lord
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    Doug Lord Flight Ready

    =================
    Your own quote : "A product that is a known challenge to operate but functions as advertised incurs no liability." Liability issues ,such as they may be, would, of course, be part of the development of the concept.
    ========================
    I am quite confident that I have a first class team to put together a working prototype. The idea is to build one boat and maybe a second down the line-not to go into production. If the results of testing the original proto warrant it then two boat testing is next. I have no interest in going into production-I want to prove beyond a shadow of a doubt by intense development and testing that this boat and this concept functions well and is a boat that a boatbuilder would want to produce.
    The electrically operated system is probably the best way to go but a manual version might be viable as well.
     
  10. Tom.151
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    Tom.151 Senior Member

    +1 to sharpii

    +1 to Munter too

    which implies -2 to Skyak
    who apparently doesn't get it, or doesn't want to get it
     
  11. Skyak
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    Skyak Senior Member

    Doug,
    do your own due diligence, but from what you describe above you could avoid liability issues.
    If the boat can be operated safely without the electrical power then all it is another aggressive performance boat. The NA fully comprehends safety. Document it well and you are covered.

    If you just have a power input to your system that the owner/operator can electrically power for convenience -no problem. Just like most winches have provisions for adding electrical power. If the user automates that control I am pretty sure you are in the clear also.

    In the 70's the domestic small plane industry was wiped out by liability law. The industry was resurrected as kit producers.
     
  12. sharpii2
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    sharpii2 Senior Member

    I remember a famous quote from Dick Newick:

    "The price of speed is accidents" Or something like that.

    When the ballast is at the end of the fully extended trap wing, there is only diminishing reserve stability left.

    A sudden leeward roll will not only completely wipe that out, but will do so with a surprising quickness.

    The ballast could be pointed skyward long before the skipper slackens the main sheet.

    This is most likely to happen in a stressful situation, like trying to get back to port to beat a sudden storm, or, more likely, trying to win a race.

    Once this vessel rolls more than say 90 degrees, it's all over. Unless it has a bulb keel as well. If it has one of those, much of the high performance will be taken away by it.

    Speed vs. safety. Always.

    The wing tips may be intended to create lift when immersed. But would they? Always? Or only when enough wing is extended on the lee side? And there's enough hull speed? And the angle of attack is correct?

    The way I see it, there is not that much bad judgment needed to flip this thing.

    And, so far, I haven't seen a statement on how you intend to right this vessel from a capsize beyond 110 degrees.

    It might be fast. It might be workable by a skilled handicapped sailor. But I would never call it safe.
     
  13. Doug Lord
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    Doug Lord Flight Ready

    In order to create the scenario that you did above , you have to totally ignore the fact that the wing+ ballast is controlled by a joystick with the skippers hand on it at all times-particularly so in stressfull situations. I think that your scenario is not possible. Whether or not it is determined that an automatic system should move the wing once, say, a 45 degree angle is reached the wing would never stay in a maximum extended position if the skipper was still concious and would within a couple of seconds or less be deployed to right the boat. Don't forget that the wing has enough buoyancy to bring the boat to a 25-30 angle of heel with all the weight at the lowest point! If the joystick failed, the skipper dropped dead, and the power died the wing would still right the boat because the ballast would automatically move toward the lowest point due to gravity. This boat may or may not have masthead buoyancy-that will be determined in testing. I doubt that it will be necessary-but may be included anyway. Testing.
    Now, my original concept of an 18 footer using this system included a bulb on the daggerboard and still had high numbers that included above 30% on Bethwaites SCP/total weight formula which indicated it would plane upwind.
    All you have to do is look at the numerous sportboats with bulb keels that plane including the Quant 28 and 30. So I would have no compunction whatsoever about adding a bulb to this thing if testing shows it needs it. However, I'm convinced it won't because of the designed in characteristics of the Wing which will in every case allow the crew to right the boat without moving more than a single finger.

    Original 18' high powered foiling/foil assist version with ballast bulb:
     

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  14. Skyak
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    Skyak Senior Member


  15. Doug Lord
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    Doug Lord Flight Ready

    Well, the MPX Fire Arrow Test Model has begun testing-in only four test sails she is foiling very well-stable and fast. Testing will continue to improve performance and refine the design but I'm beginning to work on getting a prototype of the Crossbow fl sailing.

    Here is a picture of the Fire Arrow during testing on her 4th day of sailing:
     

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