Design for DSS-Foil Assist for Keelboats

Discussion in 'Sailboats' started by Doug Lord, Dec 6, 2011.

  1. Doug Lord
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    Doug Lord Flight Ready

    Foils

    -------------------
    Depending on the boat the movement of the dgr/Ctrbd forward on multihulls may be an added advantage especially if it is a lifting foil. Two examples: 1) the A Class Mayfly uses fairly radical twisted, S curve foils with the dgr's placed much further forward than "normal", 2) the pioneer in moving a board(w/o vert. lift forward) was the Arc 21(by Bill Roberts) cat using what its designer called "shared lift"- in essence the boat had a smaller than normal daggerboard and bigger than normal rudder each contributing to lateral resistance. http://www.aquarius-sail.com/catamarans/arc21/index.htm
    I'm convinced well designed foils on monohulls or multihulls can do the things for speed everybody knows about but they can also improve the boats handling in rough conditions. Greatest example to date of lifting foils improving speed and handling in multihulls is Banque Populaire V-the fastest boat aroundthe planet-sailed the whole distance using curved lifting foils with zero failures. DSS has been shown to improve handling and "ride" on monohulls but the best example to date of the use of curved lifting foils on a big mono is probably Virbac-Paprec III, an Open 60 that along with Saffran pioneered the use of such foils on leadbellies.
    ============
    DSS web site-some computers(like mine have trouble with it) but it is loaded with info if you can access it: http://dynamicstabilitysystems.com/#/profile
     
  2. Silver Raven
    Joined: Oct 2011
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    Silver Raven Senior Member

    Gooday again - 'D-L' - thanks for that. I was going to mention 'BP-5' - but thought people might think I was nuts (well - more than ??) - however - even when driven VERY hard (& backing off) I did notice that 'BP-5' didn't seem to be loosing-it with respect to the leward ama bow.

    I'm not convinced that a curved foil is better than a inverted 'T' foil - as I don't have enough knowledge - SO - - Help Gary - who does know. I'm sure I wouldn't go for Fischer's 'S' foil at this time - but that's because I don't know enough.

    Again - thanks chaps - Your continued - 'PMA' is SUPA & is what this place should be all about. 'PMA' - positive mental attitude. It got me out of an 'orin-lung' & back to tearning to walk & - as the book says - 'I can jump puddles' .

    Please - let not the 'nay-sayers' win - cause that would spoil the - positive learning curve - for all the rest of us. Ciao, james
     
  3. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    -------------------
    Don't forget an "L" foil(pointed inboard-not outboard). Greg Ketterman considers them to be superior to a T foil on a sailboat in some applications.
    --
    You might find the first 5 pages of this thread interesting-right up to Kettermans comments that I posted. I was all excited about a curved lifting foil pointing outboard because I thought that would get some RM. Ketterman straightens me out rather dircetly but I appreciated it. Mal Smith also contributed to my understanding on the subject.....
    http://www.boatdesign.net/forums/sailboats/dinghy-design-open-60-influence-36401.html
     
  4. Paul B

    Paul B Previous Member

    You are correct. I believe it was Alberto Calderon who had a proposal for a 12 metre with no ballast keel and "wings" sticking out both sides of the boat.

    These were basically very long (12 feet each side, IIRC) foils like DSS, only both were always deployed and both should have always remained submerged.

    They differed from DSS in that they were adjustable for pitch. The leeward foil would be set to push up, while the windward one would pull down. Downwind both would be set to pull up, or maybe be neutral.

    There was a published sketch of it somewhere. I think the Big Boat challenge by Fay put a stop to any thoughts of developing this idea.
     
  5. Paul B

    Paul B Previous Member

    Careful. The true believers aren't happy when facts are presented.
     
  6. Cheesy
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    Cheesy Senior Member

    Thats interesting, it is not what I was talking about though , not surprising (that there is yet another old example out there). It was a 12 foot skiff. To be honest though I cant remember if some one had tried it or they were going to try it, the conversation was at the bar after a days racing talking about the DSS T30, which we happened to beat in every race on a little 6.5m boat with a reasonably modest sail area......
     
  7. sean9c
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    sean9c Senior Member




    I think you possibly mean Brace Brace Brace the 7.5m Welbourne design and the Shaw 650
     
  8. Doug Lord
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    Doug Lord Flight Ready

    ----------------
    Calderon was an inventor of CBTF-(canting ballast twin foil). He also patented a powerboat hull that used fins. I seriously doubt anyone would have tried to but wings on a legal 12 meter with no ballast!
     
  9. Cheesy
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    Cheesy Senior Member

    No Im in NZ and it was a T30, correct on the Shaw 650 though. In the same regatta we saw some interesting traits of the DSS when the boat gets hit by a gust and heals... Im sure I cant give a valid hypothesis on this though as I haven't designed or sailed on a DSS boat (Im thinking it has something to do with the lift vector of the foil and the lack of lift in the horizontal plane from the keel once a certain angle of heel is reached). This was all before BBB was even built, there were some renderings of the BBB hull scattered around on a few tables though
     
  10. Cheesy
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    Cheesy Senior Member

    I dont really know who Calderon is or what he has to do with a 12 foot skiff???
    Or for that matter if you are talking about a 12m why couldnt it have ballast and use some sort of DSS system? All the DSS boats I have seen still have ballast
     
  11. Paul B

    Paul B Previous Member

    The boat would have had to have ballast. The 12m rule had a minimum dspl. I believe AII was close to that limit.

    My comment was the big hunk of external lead would have been eliminated due to the stability of the pre-dss gizmo. The lead would have been moved to internal ballast. This would have allowed a lot less drag from the keel and a better foil shape (much like the daggerboard half and one tonners of 1977).
     
  12. Cheesy
    Joined: Aug 2008
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    Cheesy Senior Member

    Got you, I was trying to figure out what Doug was talking about, he must have quoted the wrong post. I think it would be more surprising if DSS hadnt been tried before!
     
  13. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

  14. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Design for DSS- Infinity 36

    More pix of the Infinity 36 training in St Tropez:(first pix post 159)

    click-
     

    Attached Files:


  15. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Attached Files:

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