Monohull Speed: Speed Dream by Vlad Murnikov

Discussion in 'Sailboats' started by Doug Lord, Jan 8, 2010.

  1. Doug Lord
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  2. Paul Scott
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  3. Paul Scott
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    Maybe. It does look French! But I think a paravane may also be a hangglider?
     
  4. Doug Lord
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    ==================
    After scrolling way down I found this:

    Summer-2001
    First test of the Paravane concept using a Marström M-20 catamaran. In the light summer breeze we sailed up to 20 kn in the beautiful harbour of Loftahammar.
     
  5. P Flados
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    P Flados Senior Member

    A small scale model para-vane / kite (French I think) has been shown to work for brief runs.

    The only full sized para-vane / wing I know of is the "Swedish Speed Sailing Challenge" at http://www.trampofoil.com/speedsailing/index.html. This seemed promising for a while but seemed to go inactive in 2007 with no explanations or updates since.

    The info from http://www.peterlynnkites.com/news/0610news.htm does have a lot of interesting stuff. Especially the "hydrofoils that work as such until a certain threshold speed, then rise to sit on the water's surface and plane" I had thought of this before, but had previously not seen the concept discussed.

    I only know of only one Kite propelled speed sailing boat effort that seems active, http://projet-dared.com/..
     
  6. Doug Lord
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    Speed Dream

    Here is the Brian Hancock article about Speed Dream that was on SA earlier this week:
     

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  7. SteveMellet
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    SteveMellet Senior Member

    1 person likes this.
  8. Doug Lord
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  9. P Flados
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    P Flados Senior Member

    From a basic physics standpoint, the idea of a lead bulb on a beam that swings entirely clear of the water on the windward side is an efficient means of generating large righting moments for a fast mono hull.

    I do not like it for anything other than a point A to point B record attempt craft. Even for this application, there are probably better approaches.

    The power required for swinging the bulb to the desired position, the structural requirements for the hinge and beam, the mechanical design of the pivot mechanism, the consequence of sudden loss of overturning moment (capsize to windward) are all issues.

    Fast mono hulls is not an area that I spend much time thinking about. However, something did come to mind as an alternative to the above. A curved sliding beam with a ballast pods on each end (very small vesions of Hydroptere's amas would have good areo properties along with a planing lower surface just in case there is water contact). I threw together a cross section sketch (attached) that shows the concept.

    The sliding beam is fully extended to windward and the windward tank contains water to generate the desired righting moment. The boat is operated with a lot of windward heel. A leeward canted foil is rotated up out of the water and the windward canted foil is rotated down to a good angle where it generates some positive vertical lift. The windward heel also allows the rig to generate some positive vertical lift and the weight of the rig generate significant righting moment. The windward heel also shifts the CG of the actual boat & crew to generate some righting moment. All of the above adds up to allow very fast mono operation.

    Approaching a tack, the boat will be allowed to slowly swing over to a leeward heel while water is transferred to the other tank using gravity. After the transfer is complete, the boat is brought to the new heading. Just after going head to wind, the boat will be heeling slightly to the new windward. At this point the beam is fully extended to the new windward. Again, gravity will be assisting you most of the way.

    The ballast tanks would not be filled to capacity (50% ??). If things go wrong and the boat tries to roll to windward, the ballast tank actually become a planing surface and/or flotation pod. The design helps you avoid a full capsize instead of driving you toward full capsize on loss of overturning moment.

    With the boat at rest (beam centered and ballast drained or evenly split) it would look like a funny tri with both amas way up out of the water. However, since the boat is designed to operate with ballast tanks out of the water it is a mono using traditional definitions. Kind of like the flotation bags that can be placed out on the hiking wings of a moth.

    The boat could also be viewed as a hybrid since it could be operated with the windward tank/pod/ama skimming the surface to minimize the need to constantly adjust heading and/or rig trim for roll control. Given the above, there is a possibility that any record as a mono hull could be challenged. It would probably require a continuous video record showing that the boat "operated as a mono hull" for the run.
     

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  10. Doug Lord
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  11. P Flados
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    P Flados Senior Member

    The weight and orientation of the rig as either a help or a hindrance is a HUGE factor. The vertical forces generated by airflow when a rig is leaning (either way) are also big.

    Every time I see photos of big high dollar racing monos heeled way over to the leeward, I cringe at the thought of how much the angle of the rig is working against what it wanted.


    As I was responding, a really unpleasant thought popped into my head. For some emotional reason, I just do not like having windsurfers as the fastest sailors. For a while now, I was content in my preference thinking that they had pretty much topped out due to limitations on righting moment. With the above discussion, I see a couple of ways that they could get back in the game.

    Windsurfer Option 1 for > 56 kts:

    Install a ballast bulb at the top of the mast/sail. Integrate it with respect to airflow goals. Have a retractable scoop tube able to fill the bulb with water after getting under way. With the typical winsurfer heel, lots of righting moment could be generated without any impact on launching/low speed operation.

    Windsurfer Option 2 for > 56 kts:

    Install a ballast chamber at the top of a one direction cambered high aspect ratio wing. Launching and low speeds could be more of a problem, but you probably get a lot of payback aerodynamically.
     
  12. Gary Baigent
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    Gary Baigent Senior Member

    PFlados' idea to have an unballasted light weather monohull with water ballast to windward as the wind increases (a la crew on International canoe) is the ONLY way for a mono to come within coooee (but still short of) a multihull in terms of performance. Carrying lead, in light or heavy airs, is not the way to go. Forget lead (and diesels to move it) if you want a high performance mono. The ballast has to be out of the water. It is very simple. The Kiwi IOR daggerboard boats of the late 1970's concept was close to the correct direction for today's outclassed monohull designs - but they have to be wide enough to have form stability (not like PFlados' drawing) and the internal hull lead ballast that the IOR board boats carried also has to go. Taking on water into the trimaran-type amas as suggested by PFlados, is the stuff to use for increasing righting moment. But then you're really building a trimaran and not a monohull. Jim Young designed a 44 foot tri named Bladon Racer back in the 1970's and it was designed to carry (or jettison) water via chutes set into the float centreboard cases. But you couldn't call that boat a monohull. And a large version of a Flying 18 with flotation/water ballast wings might also be the correct way - but again, that is not really a monohull.
    Tough cheese guys, you're just floundering around - there is no answer save to go the multihull way.
    jpeg of Bladon Racer, a mid-1970's design.
     

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  13. Doug Lord
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    Doug Lord Flight Ready

    Monohull Speed Dream

    ===========================

    Gary,Gary,Gary: thats what the establishment types(yes,multihull establishment types) said to me all my life. Then, 11 years ago, in a flurry of salt spray from the west of Australia, came a little 11 foot monohull that has turned sailboat design upside down: now for the first time in the history of mankind a little monohull is the fastest sailboat under 20'(not counting kites and windsurfers). Are really you sure you want to say that that technology couldn't be used to whup even larger multihulls-say around 60'?? Or 90'??
     
  14. Gary Baigent
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    Gary Baigent Senior Member

    Doug, Doug, Doug: the foiling Moth is a small Flying 18 with inverted T foils instead of dagger and rudder. IMOFO that is the way to go - but on a 60 or 90 foot version (holy ****!) you will have to have buoyancy and ballast out there, windward for ballast, leeward for buoyancy. And sure, have foils .... but can you imagine balancing out this act plus doing the Veal Heal. Whoops! Now I'm drinking some good Xmas kiwi beer. We're a day ahead of you. Cheers.
     

  15. Doug Lord
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    Doug Lord Flight Ready

    ==================
    Yes! Merry Christmas!
     
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