Design Challenge: Trapwing-"on-deck" ballast-12'-22'

Discussion in 'Sailboats' started by Doug Lord, Oct 7, 2009.

  1. Doug Lord
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    Doug Lord Flight Ready

    Trapwing a bit larger

    Here is a spectacular concept by Julian Bethwaite, Paul Cayard and Russell Coutts for a 60' + monohull with sliding on-deck ballast-the subject of this thread. Also see below for a link to my proposal for a 60' Moth also using sliding on-deck ballast.....
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    60' Moth: http://www.boatdesign.net/forums/sa...acing-monofoiler-design-discussion-15143.html

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    Thanks again to Julian Bethwaite for the comments and information posted here:

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    One of my inspirations -that has bolstered my own work on this project- is the Bethwaite/Billoch collaboration on the concept of Pterodactyl-which was conceived of to use on-deck movable ballast. Here is the original SA article: http://www.sailinganarchy.com/fringe...teradactyl.htm
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    What wasn't known then was what Julian says about it here. I asked him to comment on the Trapwing which he did in a PM that I'm publishing here with his permission. He reveals who was behind the Pterodactyl project:

    "A few years back these pages graced a thing called the Pterodactyl, it was a big double proa that Russel Coutts and Paul Cayard asked me to do as the ultimate circuit boat. Among other things its nice to see the OMR*go that route, but Russel was big on having 3 tonne of lead on tracks moving from side to side, inside the wing beams. I thought moving water through 200mm diameter pipes would be better, but the concept has merit. Your issue is that unless you have significant tip pods, then you will never be able to react quickly enough to keep the wings out of the water. Just cant do it! "

    *Ocean Multihull Rule: it is the predominant rating rule used in Asia (and
    Australia) it seems for handicap racing in this part of the world.(dl)

    Pictures of Pterodactyl:
     

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  2. Gary Baigent
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    Gary Baigent Senior Member

    Notice that Julian thought water ballast would be better. ... but then acquiesced politically to saying that lead "had merit."
     
  3. cavalier mk2
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    cavalier mk2 Senior Member

    I should take the time to read this posting but at a quick glance how about a circular main sheet/ballast track that lets the ballast move in an arc and in and out toward and away from a central pivot? Guys like Capt. Nat started on these paths years ago but were always shot down by the race committees...
     
  4. Doug Lord
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    Doug Lord Flight Ready

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    You realize that when he said " the concept has merit" he was talking specifically about the Trapwing.... I had written him and he generously answered and allowed me to post his response.
     
  5. Doug Lord
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    Doug Lord Flight Ready

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    Cav, did you see this:


     
  6. cavalier mk2
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    cavalier mk2 Senior Member

    I'd read about the Herreshoff sliding ballast years before, he was far ahead in many ways. I mentioned the circular sliding track because I looked at the reacher and thought weight aft and to the side for diagonal stability would be needed to keep the bow up. Moving ballast ought to be able to shift like the crew on a smaller boat to do the same job. I suppose to right the craft one of the truncated amas would need to flood to assist the small ballast bulb....
     
  7. Doug Lord
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    Doug Lord Flight Ready

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    Cav, on my boat the whole wing slides and is 100% sealed. If the weight was all the way to windward and the wind died the boat would not capsize. The whole wing slides fore and aft as well..
    I was doing some research and accidently discovered the Herreshoff story-amazing. What insight those guys had!
     

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  8. Doug Lord
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    Doug Lord Flight Ready

    Trapwing Prototype

    Big news today that gets this thing a lot closer to becoming reality:

     

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  9. Doug Lord
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    Doug Lord Flight Ready

    Trapwing Prototype - and #2.

    While the Trapwing prototype gets closer to reality every day I had an interesting thing happen today. I saw a guy sitting inside on the bottom of a nice little-probably 12-14'- dinghy . I thought that that was another perfect application for this technology: the guy had to get up on his knees every time he tacked or gybed because he needed the weight to windward. While we are going to start out very low power with the proto the plan is to power it up to illustrate the performance potential of on-deck sliding ballast.
    But this little boat today has me thinking of a future prototype using a much smaller system in a boat not designed for particularly high performance but for ease of sailing. Seems like a perfect fit for the technology....
     
  10. Munter
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    Munter Amateur

    Hi Doug - given your dedication to this project perhaps you could let a few details slip on what progress you've made that is bringing the prototype closer to reality?
    Other than watching somebody else in a boat and a few more posts confirming your belief in the idea it isn't really clear that anything has actually happened.
     
  11. rapscallion
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    rapscallion Senior Member

  12. Doug Lord
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    Doug Lord Flight Ready

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    Thanks Raps-what might have been!

    pictures: "weird tech"=rendering of the NZ challenger to DC before it was seen; blue hull=whitehouse/richards flying canting keel-actually being built; other=rc model to experiment with movable ballast(not mine).
     

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  13. rapscallion
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    rapscallion Senior Member

    This might be a thread hijack.... my apologies if it is too far off topic, but it does seem related...

    Are there any tandem keel examples of a racing sailboat? Tandem keels might be a better platform for a foil assisted lead belly.
     
  14. Doug Lord
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    Doug Lord Flight Ready

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    Why tandem? Looks like DSS works well on some mono's...

    http://www.boatdesign.net/forums/sailboats/hugh-welbournss-dss-25-a-32138.html
     

  15. rapscallion
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    rapscallion Senior Member

    That's interesting... I missed that one. Has the boat been raced?
     
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