Kiwi treatment for Sunfish?

Discussion in 'Sunfish Talk' started by minifish2, Aug 12, 2013.

  1. minifish2

    minifish2 Active Member

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    We all are seeing what Emirates Team New Zealand did to the AC cup catamarans, showing up for the event with blades that enabled foiling, that sent everyone else back to the drawing board. That certainly got everyone thinking 'why not my boat, too'.

    Scuttlebutt has this video and article, http://www.sailingscuttlebutt.com/2...9fe321a925da53189&utm_source=Email Newsletter, about some innovative Laser daggerboard and rudder that could promote foiling. So why not a Sunfish version?

    We have a lot of creative and capable contributors here. Is there a do it yourself Sunfish upgrade we could come up with?

    Even if the boat doesn't totally fly in most circumstances, it would seem that properly designed lifting foils could seriously promote planing.

    This seems like too good of a breakthrough to not at least try!
     
  2. sailcraftri

    sailcraftri Well-Known Member

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    Along with my brother , we developed a hydro foil system for a Banshee sailboat as a senior college project. Not as simple say as the centerline foils shown in the video or on the Moth class. Ours had a large athwart-ship foil aft of the mast and a "v" shaped foil on a modified rudder. Ours was not great for shallow water use. But it did work. I am interested to see what the retrofit kit is for the Laser and perhaps could then develop something for the Sunfish.
     
  3. minifish2

    minifish2 Active Member

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    Hopefully, collectively we can work out something along the lines of open-source DYI foil specs on this board. I just spoke with one sailing friend who is a consulting engineer to get him started, and we have several talented folks at our club who I think we can enlist. This could be interesting.
     
  4. Kazz330

    Kazz330 New Member

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    That would be awesome on a sunfish!
     
  5. tag

    tag my2fish

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    wouldn't foils on the daggerboard just raise the board up in the daggerboard slot? ;)
     
  6. minifish2

    minifish2 Active Member

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    Yes! So we would need a locking device to hold it in place, strong enough to hold the load. This could conceivably be from the bottom, inserting the board up from below (with the boat on the side, like with that Laser foil) and having the board actually consist of a couple of parts - a fixed seating in the trunk, and the adjustable/extending foils.... or maybe more simply a more conventional type board, secured by a substantially reinforced dead-bolt type fastener on the deck.

    Or maybe something else ltogether. But you are absolutely correct, the foiling board would be load-bearing.

    This has to be doable, somehow.
     
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  7. Kevin Mc

    Kevin Mc Member

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    It would put a lot of force (weight of the boat and passenger) into a small area of the boat's bottom not designed for it. Some way of distributing that load would have to be found.
     
  8. Blue Heron

    Blue Heron Member

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    Structurally reinforcing the boat around the centerboard trunk should not be too terribly difficult. I'd glass in a couple of stringers alongside the trunk, running back and tying into the cockpit. That's the easy part.

    Also, keeping the daggerboard / foil in place is rather simple: just run a transverse strap from the deck / hull rolled lip, across the daggerboard, and fastened to the other side. Then when you were up on foil the boat would HANG by the strap. I could rig that up in about 6 minutes. (just the strap, i mean)

    What would be tougher would be handling the heeling moment while up on plane. The Sunfish has no accomodation for hiking, and hiking gear would be rather difficult to install due to the lateen rig. There IS a solution, though. Over in New Orleans a few years ago there was a group of small boat sailors who built wild boats just for the fun of it. In their fleet I remember seeing a Sunfish with wings, much like a modern foiling Moth. It looked sort of crazy, but it was faster than all get-out.

    So.... has anybody come up with a foil design yet? Also... you'd have to modify / reinforce the rudder mountings and rudder. Has anybody thought about that yet? I might just want to build one!
     
  9. minifish2

    minifish2 Active Member

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    Just curious what this refers to. Depending on conditions, we (Sunfish sailors) currently sometimes sail fully hiked out on Sunfish, similar to Lasers and other single handed dinghies. Unless you mean a trapeze orvsomething - but the other single handed dighies don't have these.
     
  10. Blue Heron

    Blue Heron Member

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    you are right... we often sail fully hiked out on many boats. But when we do, the righting moment of our weight is aided by the boyancy of the hull on the leeward side. When up on foils, you won't have this part of the righting equation.

    When I say "accomodation for hiking" I mean anything other than a simple hiking strap, like a trapeeze or wings. If (when, maybe) I'm experimenting with trim / balance while up on foils, I think I'd rather be perched on a windward wing, rather than having my backside cantilevered out over the water. It seems like it would be easier to manage.
     
  11. minifish2

    minifish2 Active Member

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    Back to he original thought though, that Laser example does not have wings either.

    Starting from scratch, I'd say defifinately stick with a proven design (which would also be other than that Laser foil) like an existing Moth. Othewise extended body hiking is unavoidble. Agian, a foiling moth is designed for this and would be preferable.

    However, this is a Sunfish discussion board - most of us already have Sunfish (and or minifish) hulls and rigs - and the question isn't basically whether there are better foiling options, there are, but since someone has crossed the threshold already with Lasers, can't we with Sunfish.
     
  12. Blue Heron

    Blue Heron Member

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    Sailcrafti's comment above is interesting, and worthy of consideration. The V shaped foils that rise above the water on either side have a decided advantage in the stability factor. They provide a means of regulating ride height above the water with having to use a mechanical mechanism, plus the built in dihedral automaitcally wants to resist heel.

    Remember the centerline, dual foil arrangement like on the Moth are used because the rules prohibit the V foil design. They felt that it might constitute a form of dynamic multi-hull, and banned it. BUT since we aren't bound by any rules, the design should probably be considered and discussed.
     
  13. minifish2

    minifish2 Active Member

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    Just a matter of interest relating to this, there's been sort of a parallel discussion about this also over on the boatdesign.net discussion boards. One of the more prolific members had some very similar thoughts on the 'V' design:

    http://www.boatdesign.net/forums/sailboats/laser-foiler-47854-3.html

    "A real good solution that hasn't been tried yet is Mal's innovative surface piercing foils mounted on a single strut-see renderings below. This would require a lot of experimentation to get right and allow retractable foils. A surface piercing foil regulates altitude with speed so you have zero moving parts. This has tremendous potential....."

    Here's one of that post's illustrations:

    [​IMG]
     
  14. Blue Heron

    Blue Heron Member

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    MiniF- I've looked at the website you refered to thanks for the link. After studying it, I think the surface piercing foils might have some advantages, but since I've got more data for the twin foil Moth designs (thus more examples, good and not-so -good) to work with I think it prudent to stay with the twin foil design. I finished up my numbersand posted them on the other thread.
     

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