Mini 650 takes flight too

Discussion in 'Sailboats' started by Dolfiman, Sep 11, 2017.

  1. Gary Baigent
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    Gary Baigent Senior Member

     
  2. Gary Baigent
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    Gary Baigent Senior Member

    Wonder if this interesting concept is what the AC designs will be like?
    Entering dangerous (monohull?) territory?
    A problem with Frog is that it is unstable at rest. And boats are at rest for a lot of the time. Have reduced this mistake with slightly larger floats - if you can call them that and set lower to water.
    The compound bow beam here maybe could be simplified by just having it fixed through hull just above WL and then curving down and up a little from there? Would be less weight yet retain the same stability? But destroy the massive? accommodation luxury.
     
  3. Boy Griffioen
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    Boy Griffioen Junior Member

    From what i read on different fora it stayed in port in La Rochelle for some years. It proved to be fast but had to be developed more and that required a sailor and a sponsor. And this one is build for the foils = 3meter rule and we have now a foils = 6.5 meter rule.
     
  4. Boy Griffioen
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    Boy Griffioen Junior Member

    I guess the daggerboard allready solved the accomodation problem :). If you wanted to make a mini out of this the daggerboard has to be a keel though. Otherwise the stability test would be a no-go. And probably with some ballast to make it self righting with 45kg on the mast. I have to read if the foils can stay or have to be in the 3m box before start. I guess not because the Arkema has the tips of the moustage foils on the outside of the beam. But you have an interesting thought @Gary Baigent bacause just above waterline there is not really an accomodation to speak of so to increase the floor height a bit would be no crime. Especially because for the mini's the waterline/gunwale has to be 75cm and a cockpit has to be added of about. 210 ltr (beam in meter /6 = cabin size in m3) I think that to add a wing on the top of the hull like drawn here or especially as with Frog would raise some eyebrows of the measuring team. It has to be a monohull :) I guess there is an (not described) maximum buoyancy that a foil may give the boat. And if the hull lifts in the stability test that would be too much.
    [​IMG]


    But it could well be that the america's cuppers have a bit of this idea. Because the information leaked was a length to beam ratio with foils of about square and NO keel!! But the foils have to be leeway resistant. The beam of the hull is still a mystery isn't it??
     
  5. Dolfiman
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    Dolfiman Senior Member

  6. Boy Griffioen
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    Boy Griffioen Junior Member

    Ouch, my french language is so bad it hurts. But nice to read! Sadly we can't see the interview without subscribing. Ah and the foils can extend to 6.5m AFTER the start so before the start they have to be within 3m
     
  7. Dolfiman
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    Dolfiman Senior Member

    Arkema 3 the foiler / Quentin Vlaminck eventually finished today 6th of this second leg in the proto class (and 7th overall), quite far from the winner Griffon/ Ian Lipinski, 1day 21h behind. Average speed on water were respectively 9,4 Knots and 10,6 Knots (in Froude : 0,606 and 0,683). I have not yet the debriefing, but he clearly cannot take advantage of its foils on this pure downwind leg.

    Otherwise, it is a confirmation for the scow bows domination. Thanks to sailingscuttlebutt.com, here below the comments of Simon Koster (Eight Cube Sersa), 3rd in this leg and first tester of foils on Mini :
    “With regards the foils, we’re really going to have to rack our brains to analyse the pros and cons in terms of the weight estimate and the use you get out of foils. We know it will be impossible to have a boat that flies all the time, so the aim would be to have foils that aren’t a disadvantage when they’re not in use. "
    “As for scow bows, we should have been doing this for a long time. It’s impressive to see how powerful these boats are. There’s no longer any doubt about whether they work or not. For bigger boats, the only issue relates to coming up with fairly solid structures. Unfortunately, the big boat classes have their hands tied in this area. "

    Mini Transat: Proto podium filled >> Scuttlebutt Sailing News http://www.sailingscuttlebutt.com/2017/11/15/mini-transat-proto-podium-filled/?utm_medium=email&utm_campaign=Scuttlebutt%204962%20-%20November%2016%202017&utm_content=Scuttlebutt%204962%20-%20November%2016%202017+CID_8021a94b46d53b3f3acb1078483ea3a0&utm_source=Email%20Newsletter&utm_term=Full%20report

    PS : Funny to note that the same day as Arkema 3, arrival of Arkema the Multi 50 as winner in its class in the Transat Jacques Vabre, for Lalou Roucayrol the skipper it is his first win in 9th participation in this transat ! . So not a bad day for Arkema team.
     
  8. Boy Griffioen
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    Boy Griffioen Junior Member

    But he got beaten by a pogo 3!! But yes the scow bows dominate. I'm guessing that the combination light narrow boat with foils makes better sense than the heavy scow with foils. With the 6,5M wide foils rule you have some space for them. The lighter tri's can start flying from about 5knots of true wind. That is a much wider use of the foils. That would mean a full 2nd leg of flying this transat if the autopilot could do that!! If only we could make a monohull with wide foils and almost no ballast that can take heavy seas :)
     
  9. OzFred
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    OzFred Senior Member

    Which ocean racing trimarans start foiling in 4kn of breeze?

    Unfortunately the laws of physics and safety mean that may never happen. Foils are an extremely unreliable source of righting moment and don't work at all when knocked down or capsized. :)
     
  10. Boy Griffioen
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    Boy Griffioen Junior Member

    The DNA performance TF 10 claims such numbers. But i check my source maybe i did not remember correctly. At least below 10 knots.

    I know just foils ain't going to cut it but maybe a combination of semi buoyant foils in combination with self righting ballast but not more than that. Maybe combined with a canting mast, or a easy to depower sail who knows.
     
  11. TANSL
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    TANSL Senior Member

    As the lift exerted by the foils is a function of the squared speed, going from 4 knots to 10 knots means getting 6.25 times more force, which is not a small increase.
     
  12. Boy Griffioen
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    Boy Griffioen Junior Member

    Correction it was 8 knots not 5. Sorry, my bad. But it would still mean that foiling would be possible for most of the 2nd leg of the transat.

    Quote from them:
    This is the new foiling TF10 trimaran. A hightech carbon fest, allowing sailors to foil easy from about 8 knots of windspeed. It was designed from scratch as a helluva fun foiling package and we believe that goal has been accomplished!

     
  13. CT249
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    CT249 Senior Member

    Scows and snubs have worked in many classes with big rigs, but in lots of ways they are not really an advance - they are just effectively bigger boats, and we all know that bigger boats go faster.

    There were many cases in the Australian Skiff classes of boats being designed longer than their permitted overall length and then being cut down to length. Effectively, a snub-nosed 14 Footer was just a 16 footer with the bow cut off. The question is, what do you gain? You've basically taken a 16 footer (with a 16 footer's rig, and crew, and cost) and cut it down to make it a bit slower to let it fit into a slower class. It's not really advancing the art of sailboat design, or making a more efficient boat. It's arguably just as much a "rule cheat" as the bumps and distortions on an IOR boat or ORC boat.

    Last time I checked, a Mini was about as fast all-round as many 30 footers; had a rig bigger than many 30 footers; and cost more than many 30 footers. That's fine, they are great little boats, but it does underline how once you try to take every dimension to the maximum then you end up encountering diminishing returns. Scow bows could well be just an example of that.
     
    Last edited: Nov 17, 2017
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  14. CT249
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    CT249 Senior Member

    Much of the issue with the claimed foiling wind limits seem to be that we don't get any objective tests, and also that a wind light enough to leave a glassy surface in a place like the middle of Lake Garda can still be more reliable than the lighter winds you get in other areas.

    I found this is an interesting vid; it's a mate on an old Olympic class windsurfer. In many of the shots the water is glassy (although there are leftover waves - probably the wind had been stronger earlier) but he's still experiencing way more than 5 knots of true wind. Around 2:30 on the board is slicing at speed through a glassy water surface. Imagine if you just cut some of those shots against a background of the trailer yacht and the little Hobie that were barely moving. The contrast in the speed would make the board appear five or six times faster than the trailer yacht. In fact while the board is an amazing light-wind performer, it's only about as fast all-round as an International Canoe, Musto Skiff or 505.

    It just shows how deceptive videos can be when it comes to allowing us to estimate windspeed and the comparative all-round performance of various craft.

    Canting masts are lethal when they are canted the wrong way, and like foils they probably do basically nothing when you're in a knockdown and speeds are low. Same with an easy to depower sail; multi sails can be easily depowered but they still fall over.

    As an analogy, if it was all just about balancing steady forces then sailing an 18 Foot Skiff or International Canoe would be easier than sailing a Laser, because they have more righting moment. The problems don't come in steady sailing, but when speeds are low, and what are foils doing then?
     

  15. Boy Griffioen
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    Boy Griffioen Junior Member

    Canting masts are lethal when they are canted the wrong way, and like foils they probably do basically nothing when you're in a knockdown and speeds are low. Same with an easy to depower sail; multi sails can be easily depowered but they still fall over.

    I read about a self-canting mast with the foot on a curved rail. That would maybe help a bit. I think the two wing rig that was designed for Monitor (early foiler) would be interesting. It is buoyant and also low. And you could play with the angle of the masts to gain extra stability.

    But yes foils are useless when you stop moving. That is a problem. But they could help to let you make the hull a bit narrower and the ballast a bit lighter at the cost of easy powering up the sails after a tack or gybe or full stop.

    Talking about safety, what would a scow do when it turtles. I think it would have a hard time getting up again.
     
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