Where are the catamaran innovations?

Discussion in 'Multihulls' started by simon, Feb 1, 2009.

  1. sigurd
    Joined: Jun 2004
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    sigurd Pompuous Pangolin

    I disagree. When hitting something rigid, non kicking up appendices, whether they have horizontal foils or not, will have to stop the whole boat within the deflection distance of the structure. Those are many G of deceleration (sic?).
    If the foil is designed to lift half the boat, it is designed for 1/2g lift, and, according to my last post then the deceleration by hydrodynamic drag will be "close" to those 1/2 g.
     
  2. Chris Ostlind

    Chris Ostlind Previous Member

    Perhaps our friend Doug can supply a list of craft with damage free, lifting foil systems? Systems, which not only do not transmit damage to the mounting structure, but when impacted at speed, also do not incur damage to the lifting foil itself.... not even the leading edge.

    Trimaran Groupama 3 couldn't do it and they have a budget. Oh, baby, do they ever have a budget. One of their lifting foils took a hit in the Southern Ocean and then, just a short time later, the entire ama broke in half, capsizing the boat while it was looking to set a new record Round The World for the Jules Verne award. Just imagine the problems for someone with lesser means when it comes to engineering and build techniques.

    The automotive industry has been working on an engineered set of systems that can totally absorb impact damage for 30+ years and they have not found a solution. They have R&D deprtments with budgets that run in the millions of dollars a year for just such an application and there are some dozen different companies doing this work independently. The best they can offer at present is a means to help protect the occupant. For a flying boat, if you want to absorb all the impact energy, you would be looking at a system with such structural weight that it becomes entirely impossible to justify for the type of craft which can also foil. So, you either live with it, or you move on to some other solution. There's no free lunch.

    Some folks live in pretend environments. Others live with reality.

    Did this post sound too much like an attack dog... Or did it actually sound like reality hitting home with a thud?
     
  3. sigurd
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    sigurd Pompuous Pangolin

    Oh.. whatever... deleted.
     
  4. Chris Ostlind

    Chris Ostlind Previous Member


    That's just it, Sigurd... you didn't find it out of taste enough to not post it to begin with, just lousy enough so that it wouldn't be hanging around on the Web for eternity. Instead you used a passive aggressive technique in which you get to say your poor taste items and then quickly act like it was never said at all. It's not just the words, Sigurd, it's the process that puts you in your own category of poor taste.


    Really? Maybe it's because I bring a set of points to the discussion that you just don't happen to like. Whenever you see them written, it makes you have to deal with that which you refuse to address at all. Don't feel bad, Sigurd, you have a staunch buddy in the game of foil mania who thinks that all boats need to be foil equipped and the world will be just wonderful. I tell you what.... since you and Gary and Doug like the idea of the number of posts as a means to justify the value of the argument, take a minute and go back on any of the foil threads and count the number of posts by Mr. Lord alone. Go ahead. I think you'll be amazed at how many of the whole lot are his posts, with most of them saying absolutely nothing that extends the conversation.

    You want haranguing....? I give you Mr. Doug Lord.

    I understand Baigent's take. He's much more of a dedicated, out there doing it foiling enthusiast, rather than a pure wannabe like your buddy, Lord, there. I look at my interchange with Baigent as friendly boxing over a common topic. Lord is of another realm altogether.


    Sigurd, here's the point... I don't have to put forth any solutions. I didn't make the wild suppositions in the first place. And if you really did your homework on your comments, you'd find that over the years here, I have offered up tons of suggestions. I've outlined whole plans of attack for issues, which were being completely ignored. Go look it up, my friend and you can come back anytime you like and change your position.

    I'm pointing out that which is apparently too complicated, or too scary for the foil proponents to address. Lots of very educated people have pointed out similar things on these threads and the cognoscenti have continued to ignore the facts before them. They seem to be quite happy in the cloud of self deceit and it's oh so disturbing for them when they get it tossed-up where they have to address the power of the points made.



    Hey, great, Sigurd. You are apparently one of those chosen few, anointed by the Gods to be absolutely perfect in your manner and grace.

    Don't kid yourself, bubba... you're just as screwed up as the rest of us.

    Here's the clue of the day.... If you don't like it, don't read it. Nobody is forcing you to engage in that fashion. Get your fingers over to the User CP like I shared with you and put whomever you like on ignore. In the meantime, this is a public Forum. You put your opinions up here for the group to look at because you apparently have something to say. If your opinion looks half-baked to the readers, don't get all huffy when someone, or even many, suggest that your opinion is in serious need of a rethink.


    You have your take and I'll have mine.

    For the record, I think you have some interesting observations to contribute. Just quit sneaking around in order to look clever when you really have something you want to say.
     
  5. RHP
    Joined: Nov 2005
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    RHP Senior Member

    Quote from a certain film:

    "Round up the usual suspects". :D :D
     
  6. sigurd
    Joined: Jun 2004
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    sigurd Pompuous Pangolin

    "Hey, great, Sigurd. You are apparently one of those chosen few, anointed by the Gods to be absolutely perfect in your manner and grace."

    I usually am but I don't attribute it to the gods.
     
  7. sigurd
    Joined: Jun 2004
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    sigurd Pompuous Pangolin

    By the way that rubber band shown in the drawings, as soon as the rope from the wand snaps, would pull the foil back, helping pulling it away from the thing that impacts it.
     
  8. tspeer
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    tspeer Senior Member

    I have heard of a small powered hydrofoil that had a kick-up stern foil and hit a sand bar. It took the transom right off the boat.

    For that reason, it may be better to allow the foil to break free completely in a serious impact. If the foil is tethered to the boat, you can pick it up afterward.

    Here is how Mark Pivac handled retracting the foils on hi 12m catamaran design, Spitfire:
    [​IMG]
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    [​IMG]
    [​IMG]
     
  9. sigurd
    Joined: Jun 2004
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    sigurd Pompuous Pangolin

    Tom,
    Nice boat and foil systems! I don't see any kickup or obvious weak points on it. You made a good point with the sandbar. Like I said I could be wrong about the hydrodynamic loads on a kicked back foil, but if I ain't then the foil mustv'e got stuck in the sand! (or there was a fault in the kickup system)

    The solution you suggest, releasing the whole thing, could be accomodated with a transverse pivot axis, if it did not go through the hull.
    The UHMWPE bearings around the carbon shaft would be on the deck, but split, and tied together with weak string. Crashing, both bearing strings would break but one would have to consider what the axle would hook into on its way back. Maybe it would catch a shroud, and bring the mast down!
    It could be done much the same way with a longitudal pivot axis as well.
    Ofcourse if the foil wasn't shaped like an anchor (T-foil) then there would be little point in releasing the whole thing, if it already could rotate backwards?
     
  10. Gary Baigent
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    Gary Baigent Senior Member

    Excellent stuff Tom Speer, what an interesting cat of Mark Pivac's. Did it having inverted T rudders?
    Of course you wil know about this system here on the pioneering Williwaw:
     

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  11. mdcf
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    mdcf Junior Member

     
  12. drmiller100
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    drmiller100 Junior Member

    Hmmmm, It seems pretty obvious to me to use a trailing arm style suspension, with a severe falling rate spring.

    The theory would be to have the spring at full extension, with the suspension holding most of the weight.
    We assume the boat will be moving forward when it collides with something.
    When the foil collides, the foil swings back and up, and the spring "over centers", and after the initial collision the foil can get out of the way.

    Once the crash is over, the spring pushes the foil back down, and the foil is ready to go.

    All this begs the question of who wants a sail powered hydrofoil? Someone who wants the speed of a motor boat with the complexity and unreliability of wind, but who finds sail boats too relaxing and not complicated enough.
     
  13. Chris Ostlind

    Chris Ostlind Previous Member


    Dang, Tom.... You're just so dang negative. Apparently, The Foilistas have suddenly lost their sack.
     
  14. sigurd
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    sigurd Pompuous Pangolin

    A small torpedo launch tube could be faired in with the T join, obliterating any obstacles. When the wind was low, the torpedo could serve as propulsor.
     

  15. sigurd
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    sigurd Pompuous Pangolin

    There was a page on the net showing a through hull daggerboard kickup. Using two pivoted stays to the daggerboard, a long length of it would be pulled into the centreboard case, forced by the board being pushed aftwards from under the boat.
    Wish I could find it. The same principle could be used in reverse, to eject the board out of the bottom of the boat under impact.
     
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