Flying Canting Keel-Extraordinary Innovation!

Discussion in 'Sailboats' started by Doug Lord, Jan 3, 2010.

  1. Wuzzi

    Wuzzi Previous Member

    I think you are right when you say it is more than "could it work?". I also think that it is more than a simple physics problem. That's what Doug thinks it is and now, you as well, PF. It doesn't matter to me if it is for a race boat or a recreational boat. It has the same problems on both. If you put a big speeding mass on the deck of a boat, you can start to apply to insurance companies right now to get an idea as to how many injuries will result from the issues contained.

    How do you get comfortably from the aft section of the boat to the forward section without engaging the potentially very dangerous moving mass? How will it be maintained for regular maintenance while at sea on long voyages? How effective is the boat without the designed moving mass, should it break down? The list goes on for some period of time should one care to list all the possible snafu potential.

    Looking at this kind of solution as a powerful plus is only part of the overall issue and I have not read anyone making observations as to how to even list those issues, much less formulate a series of answers as solutions to same.
  2. Doug Lord
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    Doug Lord Flight Ready

    The Trapwing system is designed for small singlehanders and the sliding weight is inside a sealed "wing". The crew sits aft of the wing down inside the boat.
    Julian Bethwaites Pterodactyl, which is a big boat designed to use sliding on-deck ballast had two possible systems: one moved lead, the other moved water- all sealed inside.
    Charles Herreshoffs boat sounds kind of hairy since they ,apparently used a "dolly" with the weight on it to slide athwartship.
  3. Cheesy
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    Cheesy Senior Member

    Fundamentally this system could work, it may (will) have some compromises on Dougs proposal though, most likely in terms of the mass transfer speed, it will also require some reasonably clever control systems to protect itself from itself so to speak. A given motor will have the torque to move 70kg (made up reasonable number) up an incline in whatever time, you could design a system around these parameters it it might work.... It may also not work, your motor has a speed range where it will provide the required torque and speed, what happens when you put the thing on its side and have to pull the mass up in a near vertical direction? the required torque is much higher. There will be many such compromises such as this to consider.
  4. Wuzzi

    Wuzzi Previous Member

    Sealed inside? How does it get repaired simply and quickly when something goes wrong in tough conditions? Was Bethwaite's dinosaur ever built? I suspect that there's a very good reason it has not.
  5. Doug Lord
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    Doug Lord Flight Ready

    If you capsized with the wing extended max to weather, turning 90 degrees, the weight would want to go to the low side automatically. Since the buoyancy of the wing is far in excess of the weight inside it ,as the weight moves down, the wing moves down causing the boat to right itself. The rig and its masthead buoyancy has to stay attached to the boat for the Trapwing version without a keel to self-right. There is almost no conceivable scenario where the weight would have to be lifted vertically because of the buoyancy of the wing automatically tending to right the boat and center the weight. However, the power would be enough to do that slowly.

    click on image:

    Attached Files:

  6. CutOnce

    CutOnce Previous Member

    Huh? This doesn't make any sense.

    The buoyant hollow "wing" and the weight it contains will achieve floating balance, with only the excessive buoyancy causing the top of the wing to emerge above the water. Think iceberg. Once balance is achieved, there will be no extra lift to automatically right the boat as it will be happily lying on it's side as long as the hollow mast keeps the rig on top of the water. The boat and the wing are two different floating entities at this point with the weight of the wing/ballast having no real effect on the capsized hull. The sliding join between the wing and the boat effectively detaches any effect of the wing's buoyancy from the hull.

    Unless physics don't apply.

  7. sean9c
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    sean9c Senior Member

    Why does your image only show the capsized boat at about 85 degrees rather than masthead in the water? Appears that if you indeed showed it as would be (masthead in water) you'd have overcentered your wing so the ballast in the wing, no matter what it's location in the wing would be holding the boat down. Also a little surprised on how low in the water you've indicated your hull would float. My guess would be the hull would float higher, which would also make selfrighting more difficult
  8. Doug Lord
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    Doug Lord Flight Ready


    Wrong. The buoyancy of the wing is far in excess of the weight sliding inside it. As the wing goes more into the water to the point the weight is centered or lower as required*(that will require some power-manual or electric) the buoyancy in excess of the weight causes a righting moment that increases dramatically as the wing tilts and the boat begins to rotate. The CG of the crew is at the heeled CB of the boat, whereas because of the athwartship pivot of the wing, the CB of the wing is much closer to the mast tip and of such magnitude to start the righting which only accelerates as the boat begins to rotate. The process is enhanced on the 18 which has a small ballast keel. On the 14 no ballast keel is necessary. I imagine that in most cases this situation will never develop since the wing moves fast enough that it would only be caught full out and 90 degrees very rarely. But thats the point of the sealed buoyant wing where buoyancy far exceeds the weight in the wing.

    *added for clarity 6/11/12

    Attached Files:

    Last edited: Jun 11, 2012
  9. Paul B

    Paul B Previous Member

    It is simple. All that you point out has been pointed out to him in past discussions. So he manipulates the "data" to get the result he wants.
  10. CutOnce

    CutOnce Previous Member

    Are you kidding me?

    If the ballast amount is 75 pounds, and the wing structure weighs 25 pounds, the thing will displace 100 pounds of water. In your explanation (which should get an award for confusing double talk) you now add external power and control to something that was supposed to be "automatic". How much buoyancy is needed? 100 pounds of lift to reach neutral buoyancy. Any more will not make it float any higher.

    Increasing displacement of the "excessively buoyant" wing structure can only be done by decreasing displacement of something else. The "excessive buoyancy" is pointless unless it is immersed to the point it provides lift (at which point it isn't "excessive" any more).

    What you are proposing is using an electric motor (or manual block and tackle ) to transfer displacement from the hull/crew/boat to the wing structure. From appearances you seem to think this will provide an off axis lever arm which will create a predictable righting force.

    This whole concept is WAAY more complicated than you represent, and a RC model test using a moving battery pack is not even close to what you are proposing here. That is just my opinion, and please proceed with your project full speed ahead.

  11. Doug Lord
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    Doug Lord Flight Ready

    Open mouth, insert foot.......Your comment is vastly off base and very surprising ! This statement is in error: the total buoyancy of the immersed portion of the wing does NOT necessarily correspond to the buoyancy required to simply float the wing. First, the wing is physically attached to the boat. Second, the total buoyancy of the wing is a function of its shape and volume!!! It's volume displaces significantly more water than the simple ballast + wing weight depending on how much of the wing is immersed. * The net buoyancy of the wing is controlled by the crew(either manually or electrically).

    * (Total immersed wing volume in cu.ftX 64)-(wing weight+ballast weight)=net total buoyancy in pounds of immersed portion of wing.

    From post 203:
    ** the power is required to force the wing down to create enough excess buoyancy to begin the righting process. The wing would rise to the surface(righting the boat) even with the weight at the lowest point when the boat is 90 degrees and the wing fully extended down!
  12. fng
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    fng Junior Member

    you might also need to close in the back of the hull to get more aft buoyancy or it may well roll aft with the persons weight and try to go turtle.
    when you wipe out most sportboats you have to very quickly suffle fwd to stop this. had to do it on a T750 a few times.
    Is the pilot of your model weighted proportionatly ? maybe you should try it and youtube the results
  13. Wuzzi

    Wuzzi Previous Member

    I'm truly sorry about your mom, Doug, but perhaps you should take a break from all this for a period of time as you are not making any sense at all. I think that everyone here would understand if you needed to collect your thoughts and slow-down the swirling effect that sometimes happens due to the loss of a loved one.
  14. P Flados
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    P Flados Senior Member

    A fully enclosed "wing" with an weight inside is just an engineering effort (not necessarily easy, but no one said anything about easy). Ensuring that it has sufficient displacement to offset the weight (if submerged) is again just a "do it" kind of thing.

    Those that attack Doug on these points must not realize that he really does understand quite a bit of theory and mechanics.

    Practical in full scale is different. This is where I usually get chuckles reading some of his posts. Dreamers are a good thing (they prompt innovation), but good engineers are always looking for what will be the “so thats why this feature is not in common use” revelation. Chasing dead ends is really not a lot of fun.

    For the topic at hand, getting the righting moment desired is a function of weight and distance off of center. A long big wing with an internal weight can meet the functional requirements, but at what cost? Not only would it be a big effort to make it work but then you probably end up with a lot of air drag and you end up with the structural elements that are likely to be in the way.

    For a practical general purpose craft, forget it, There are many other choices that provide more results for the cost/effort.

    If you are looking for a way to go faster in a very narrow little operational band, righting moment without any extra water drag can provide a big payoff.

    Just to be clear, I do not think that a moving ballast system is a good choice for any “mainstream” boat. I see no place at all for this in the context of the average Joe (and his insurance agent). Speed sailing is not even close to “tolerable risk” for anyone not real close to “crazy” in the first place. Remember Sailrocket (flying flips anyone), Rob Douglas's broken arm, Hydroptere's pitchpole at speed, MI's self destructing wing, etc.

    The use of this feature is only worth considering if you are trying to go for the physics that helped the Crossbow series of boats perform while getting full performance on either tack. If max mono-hull speed on both tacks is the focus, why would you take something like this off of the list of choices?

  15. Doug Lord
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    Doug Lord Flight Ready


    Paul, thanks for your comments. I think a boat using a version of a Trapwing system on a planing dinghy under 20' could be mainstream for singlehanded sailing in a self-righting boat.
    Many sophisticated disabled sailing boats use electrical systems for all aspects of sailing-from sheeting to steering-and the electronics have an excellent track record. There is no reason that electrically movable ballast in a system like the Trapwing could not be developed to be effective, very fast, easily trailerable, easy to store and most importantly self-righting -even in smaller versions w/o a ballast keel. Smaller versions could use just a manual system, if desired.
    In terms of cost I don't see the wing as too significant a cost item after the design is developed.
    As for air drag take a look at the drag of trapeze dinghies or even the Moth where crew air drag is a significant portion of total drag. This concept uses a streamlined wing which would have very low air drag.
    The wing simply pivots for trailering.
    I don't think this concept or the tech it represents is a dead end and there are a number of experienced sailors who agree. Whether it will ever get built or not is a question that could relegate it into the dead end category at some point-but not yet.
    This type of boat offers the potential of easy to sail, singlehanded, high performance sailing in a self-righting platform the likes of which simply does not exist at this time. The fact that it does not exist is certainly not a disqualifyer of its viability. It can be done and would be a beneficial development for a lot of people-including me.
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