Foiling bilgekeels

Discussion in 'Sailboats' started by dsigned, Sep 21, 2017.

  1. dsigned
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    dsigned Junior Member

    Thinking about the potential benefit of retrofitting on older bilgekeel boat with foils. They seem to be generally built to take immense stress (as several of them were made to be able to beach), so why not make some poor man's athwartships foils?
     
  2. Gary Baigent
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    Gary Baigent Senior Member

    Always liked the asymmetric bilge board, not keel concept - except you need to lift the windward one and rely on the lee board for windward sailing. But most/all bilge keelers are fixed; both down at same time - which is inferior in performance and concept. So even if you fitted inverted T foils to the fixed keels the gain would be less than zero because of drag. However if the boards were angled outwards and you had T foils, the lifted windward one, as the boat heels, would be clear of water and drag, like a multihull. Now that would be a good performer. There was a famous One Ton design designed by Bruce King named Terrorist with lifting boards which was a spectacular winner in the early 1970s (until the concept was banned by stupid officialdom) but the dagger boards did not have T foils. Boat was exceptionally fast to weather. Which very much frightened the officials.
     
  3. dsigned
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    dsigned Junior Member

    I was actually thinking of a (relatively) high aspect ratio foil extending laterally from the root (or near it) of the keel. I would expect that the reduction in displacement due to lift would compensate for the drag?
     
  4. gggGuest
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    gggGuest ...

    It was racing under a handicap rule. With a handicap rule one of the jobs of the officials is to tune the handicap system so that any new development has no advantage over existing craft. Once there is no handicap advantage then it may be that other disadvantages (like daggerboard cases cluttering up the interior) cause people to drop the idea. So 'stupid' officialdom were doing exactly what they were supposed to do. Its a persistent problem with offshore sailing. People want a rule that both encourages new developments and ensures that every boat is handicapped equally so crew ability wins races. You can't have both: they are implicitly opposites.
     
  5. Gary Baigent
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    Gary Baigent Senior Member

    No, ggg, not handicap rule, Terrorist was/is a 1974 One Ton Cup design and raced successfully under the Rule before the officials banned the design. Britton Chance also designed a similar double lifting board boat around the same time, Fous de Vous I think it was called. But Terrorist was fast, too fast for its own good.
     

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  6. CT249
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    CT249 Senior Member

    Yes, the IOR was a rule that tried to walk the line between handicapping (ie allowing varied sorts of boats to be competitive) and development. Every rule plugs loopholes and oversights like the IOR did, which is a good thing. How many boats would have stopped racing, or never been built, if every competitive boat had to have a pair of leeboards running through the cabin like Terrorist did? One wonders how many of those who criticise such rules have ever played the game as long-term crew or as an owner.

    Of course, Terrorist would never have won if they hadn't earlier jumped on the Cascade loophole. And Tituscanby would have been soundly defeated by a Cascade type. So if they had not closed off loopholes then instead of having Farr lightweights, everyone would have been building heavy 37 foot bilge keelers that were vastly more expensive, vastly less comfortable, but marginally faster for their rating because of rating loopholes. It's hard to see why that would be better than pluggin the loopholes and allowing the development of the modern fractional rig lightweight sloop.

    At the world championships, incidentally, Terrorist scored 1-11-DNF-DNS-4, for an average place of 5th. Race 2 was fluky but she wasn't in the top two before the wind change came in. High Tension, a noticeably roomy boat, beat Terrorist two of the three times the bilgeboarder finished. The claims about her vast speed don't seem to have been borne out on the water.

    It's amazing that sailing has so many myths about how nasty powerful rulemakers run amok, stopping development. It's very odd in a sport so full of rich, powerful white adult males. Is there some sort of compensation mechanism going on?
     
    Last edited: Sep 26, 2017
  7. tspeer
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    tspeer Senior Member

    I don't think you'd get enough vertical movement of the keel from the beam of a typical monohull, assuming a reasonable amount of heel. However, this concept was used on the first cruising hydrofoil, and AFAIK the only hydrofoil to have crossed an ocean - David Keiper's Williwaw. The leeward foil was deeply immersed and the windward foil was clear of the water.
    [​IMG]
     
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  8. Gary Baigent
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    Gary Baigent Senior Member

    Terrorist was light years different to Cascade; but in fact was very conventional and even conservative with deep rockered hull for internal ballast and masthead rig common of the times; the only major difference being the lifting angled boards. And the boat was very fast to windward.
    As usual you start throwing babies out with bathwater to suit your pedantic theories.
     
    Last edited: Sep 27, 2017
  9. Gary Baigent
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    Gary Baigent Senior Member

    Agreed, it would be difficult to fly the windward foil clear on a monohull and maybe it should be a (dangerous) outfacing J and not a T - which would drag the inner foil section. It maybe possible to fly it clear with an extremist wide hull - but then you run into wetted surface and aero drag problems. Yes, Williwaw was not only very clever but a real pioneer; I was invited on board when David Keiper was in Auckland.
     

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  10. schakel
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    schakel environmental project Msc

    New idea:

    Is this a stupid idea or is it very controversial?
    In combination with batteries on board it might work.
     
  11. CT249
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    CT249 Senior Member

    But if you have an electric motor driving a propeller surely it's a motorboat and therefore a different sport? The Deed of Gift bars it anyway.
     
  12. gggGuest
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    gggGuest ...

    There was no One Ton rule (at that time anyway). The One Ton Cup in that era was raced under the IOR handicapping rule, with a rating (or handicap) limit so that all boats were raced level - ie with the same handicap coming out of the rating formula. It was still a handicap rule: make the boat longer, you got a higher rating, put more sail on, you got a higher rating, all the rest of it.
     

  13. Gary Baigent
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    Gary Baigent Senior Member

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