Everglades Challenge: the Right Boat?

Discussion in 'Multihulls' started by Doug Lord, Mar 5, 2016.

  1. Steve Clark
    Joined: Jul 2004
    Posts: 221
    Likes: 28, Points: 28, Legacy Rep: 163
    Location: Narragansett Bay RI

    Steve Clark Charged Particle

    I'm a big believer in low D/L ratios.
    Given a choice, I will always chose long and skinny over short and fat.
    At least as far as sailing and rowing boats are concerned.
    A lifetime in sailing canoes and catamarans has kind of left a mark.
    SHC
     
  2. rapscallion
    Joined: Oct 2006
    Posts: 504
    Likes: 15, Points: 18, Legacy Rep: 132
    Location: Wisconsin

    rapscallion Senior Member

    does the q23 foil setup require a ballasted keel to work? a trimaran, without ballast, wouldn't have the counterweight of the keel to offset the foil's lift. I'm wondering if stable flight would require the ballast.
     
  3. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 349, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    Q23 foils

    No, the ballast is there to make it easier to right-it has nothing to do with foiling other than that it adds to the righting moment especially when flying.
    But you could ditch the ballast and add a fourth crew just sitting in the cockpit if you wanted to. You would need a dagger or centerboard for lateral resistance. You wouldn't want any sort of "counterweight to offset the foil's lift"-any weight has to be specifically designed to add to righting moment first and then do something else like help to right the boat after a knockdown. The whole philosophy of the Quant 23 guys is to provide a safe, easy to sail boat that will foil in light air.
    On a trimaran, the biggest problem would be in ensuring light air takeoff if that was part of your design requirement.
    If the lee foil is the only one in the water at takeoff and if it is too far from the athwartship CG of the boat, then it would prohibit the main hull from flying except in stronger wind. But if you use a lifting foil on the daggerboard then the thing can be designed to lift off in light air.
    For small tri's the Q23 foils offer a lot of potential because they can allow a street legal beam which means the boat would not have to be folded and unfolded,assembled or disassembled every time you sail. That offers some pretty nifty design possibilities.
    But the biggest advantage, in my opinion, is the relatively shallow draft of the foils when sitting still with the foils deployed or when flying. And ,of course, the foils can be fully retracted.
     
  4. rapscallion
    Joined: Oct 2006
    Posts: 504
    Likes: 15, Points: 18, Legacy Rep: 132
    Location: Wisconsin

    rapscallion Senior Member

  5. rapscallion
    Joined: Oct 2006
    Posts: 504
    Likes: 15, Points: 18, Legacy Rep: 132
    Location: Wisconsin

    rapscallion Senior Member

    I love the Sharpie idea! Simple, fast, and relatively cheap. One of my favorite mono hulls is the Admiralty 30. The biggest reason I never bought a sport boat was the need for crew just to sail. I enjoy getting out on the water by myself. It clears my head.
     
  6. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 349, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    EC foiler tri

    Raps, I didn't figure you were "arguing" at all!
    --
    In the previous posts you were talking about using Q23 foils on the main hull of a tri which seems to me to be exactly the wrong place to take full advantage of them. In my opinion, the Q 23 foils would do their best if used on the amas for a number of reasons:
    1) greater RM if the center of lift of the foil is further away from the center of gravity of the boat,
    -
    2) easier to design in platform dihedral to automatically lift the windward foil without having to retract it.
    -
    3) easier to retract the foils without getting in living space.
    ---
    The Q23 foils working on a mainhull of a tri would be a pain in that you'd have to retract the windward foil every tack or gybe OR use both all the time?
    It seems to me the best foil to use on the main hull is a wand/manually controlled foil or a surface piercing T foil.
    The wand based foil has the advantage of being able to control the angle of heel and add downforce as required.
    In combination with Welbourn foils on the ama you could have a powerful, fast tri that was able to foil in light air and in relatively shallow water.
     
  7. rapscallion
    Joined: Oct 2006
    Posts: 504
    Likes: 15, Points: 18, Legacy Rep: 132
    Location: Wisconsin

    rapscallion Senior Member

    So, the Q23 foils would be reaching outward from the ama, or would the setup look more like Steve Clark's C class?
     
  8. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 349, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    It would be 180 degrees from Steve Clarks set up where the foil points to windward from the lee ama-the Welbourn foils would point to leeward of the lee ama.
    rough sketch of Steves set up:

    [​IMG]


    [​IMG]
     
  9. rapscallion
    Joined: Oct 2006
    Posts: 504
    Likes: 15, Points: 18, Legacy Rep: 132
    Location: Wisconsin

    rapscallion Senior Member

    I get it.

    Is there an advantage to using the welbourn foils vs. uptip foils on the amas other than the ability to retract them completely?

    Could the foils face inward like the C class cat?

    The Rave V is making progress

    http://www.windrider.com/blog/category/rave/
     
  10. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 349, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    I think I mentioned advantages of tradeoffs between Q23 foils and UptiP foils earlier. Of course Steves foil(or any surface piercing foil) could be used but compared to UptiP foils the center of lift would be probably be a bit inboard on boats of equal beam.
    Do you get the reason for using a lifting foil on a trimaran daggerboard?
    Another major difference between Welbourn foils and UptiP foils is that UptiP foils can generate all the lateral resistance for a boat that uses them whereas the Q23 foils do not generate lateral resistance when foiling.So with Welbourn foils you don't need ballast on a trimaran(necessarily) but you do need a daggerboard or centerboard.
    --
    I was hoping you had found some new stuff on the Rave but as best I can tell there is no update beyond whats in the thread:
    http://www.boatdesign.net/forums/multihulls/rave-v-foiling-trimaran-52050-3.html I think they may be having some trouble-I hope not.
     

  11. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 349, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.