Planing Trimarans

Discussion in 'Multihulls' started by Doug Lord, Sep 30, 2006.

  1. Doug Lord
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    Doug Lord Flight Ready

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    So the main hull was planing-is that right?
     
  2. Gary Baigent
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    Gary Baigent Senior Member

    correction: plastic sandals, not jandals, you know those awful, vile things we kiwis used to wear, slippery, sweaty, lethal - how Keith gripped that mast was more than mysterious - and he went up there like a possum with an on-fire tail.
     
  3. Doug Lord
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    Doug Lord Flight Ready

    sandals?

    yeah, but was the main hull planing? Oh, nevermind......


    Well, I guess thats it ,then....
     
  4. cavalier mk2
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    cavalier mk2 Senior Member

    A Nicol can fly with both hulls completely clear of the water unsupported by foils etc..after planing of course..Back in the 1960's Hedley took a stripped out Vagabond past 27 knots in smooth water with gale force winds blowing carrying full sail. A stronger gust hit and the boat took off to a height of 3 feet when it was discovered that flying boats need aircraft control surfaces to avoid aerobatics. They barrel rolled which is a very advanced flying maneuver not usually used by boats. At speeds over 20 knots the measured lift of all hulls , including amas, was up to 8 inches. All verified .The main hull on these boats has the main hull beam carried all the way aft to help generate lift. The easiest solution might be to take doubters sailing on a F boat so they can experience first hand the sailing qualities they are looking for stills of. This post was deleted earlier but if you don't learn the lessons of history how can you fully grasp the present let alone maximize the future? Of course you could call the lifting effects of the wing deck cheating :) but a good designer tries to make the package work together.....and now on to a more open minded topic, I'd better check out Scott Brown's forums !
     
  5. cavalier mk2
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    cavalier mk2 Senior Member

    If you reefed the main the lee hull stays up and the boat goes faster. Sailing with the right area the bow on that skinny ama does develop lift, the mainsail adds more heeling moment than drive, with it reduced it won't bury the ama, "end a story". Learning how to drive a boat takes practice, Hedley did say to sail them flat, my first year the ama was buried the second it wasn't and it was faster. Yes the main hull planes, it is similar to rough water planeing torpedo boat hulls for that reason. Hedley was a dinghy racer first and knew what he was after. Sorry about the delete comment this site is updating somewhat erratically over here.
     
  6. Leo Lazauskas
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    Leo Lazauskas Senior Member

    I'd believe it is planing if upward dynamic forces support a substantial displacement volume. I don't regard reducing the displaced volume back to its static value after the hull has squatted downwards as true planing, but that's just a personal definition.

    Also, couldn't "popping the chute" introduce an upward component of force that trims the hull and reduces the displaced volume?
    Could it just be the illusion of planing you are experiencing in the Farrier? :)

    Leo, intersecting on the astral plane.
     
  7. Gary Baigent
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    Gary Baigent Senior Member

    hey chaps, a simple question: here is USA BMW-O stooging around under half power bullshitting Ernesto and Brad, two hulls in the water, tri accelerates, main hull begins to lift out but not quite, "By Jove lads, look astern, we're planing, main hull's wake is flat, no doubt about it, we're definitely planing just like a dinghy," - skillful wing trimmer winds on more power, now we're flying on one ama, "What are we're doing, we're definitely going faster than when we were "planing" - guess we can't say we're planing anymore."
     
  8. Willallison
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    Willallison Senior Member

    It's an interesting distinction to try and make isn't it....not helped by there not being a definitive definition of what planing is!
    For my money, a vessel can be considered to be planing when (amongst other things) it is substantially supported by dynamic lift. If that is the case for the Tri's in question, then I would say that they are indeed in the planing mode. That they are also partially supported by the ama could be considered to be a moot point.
    The same could be said for foil assisted powercats such as the Hysucat ( http://www.hysucraft.com/Principles.aspx ). They are partially supported by the foils, but would anybody argue that they are not planing?
     
  9. Gary Baigent
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    Gary Baigent Senior Member

    hey, Williamson, don't introduce the f-word into this "discussion."
    The words "substantially supported" are the ones that define planing .... and some of us (the enlightened ones) maintain that the main hull is not substantially supporting itself - the "moot point", as you say, the levering ama, is the one that is "substantially supporting" the platform, not the main hull. I'm out of here, endastory!
     
  10. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Of course, if someone had a table of offsets for the Farrier main hull they could plug it into the Flotilla demo and actually estimate the dynamic forces and the variation of the displacement volume with speed.

    Just a crazy thought.
    Leo.
     
  11. CT 249
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    CT 249 Senior Member

    Leo, what's your take on the definition of "substantial displacement volume"?? That is, what is the definition of "substantial"? Do you believe that the boat should raise higher than its static waterline?


    PS Cav - I think I can remember reading about the success of Drumbeat, the Nicol Gary sailed on, so it seems those guys knew how to sail the boat and already had the practice!
     
  12. Leo Lazauskas
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    Leo Lazauskas Senior Member

    That would be a good start! Anything less would be really stretching any definition of planing, except perhaps that of a gliding flat plate.

    Leo.
     
  13. catsketcher
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    catsketcher Senior Member

    into the lions den

    Cmon guys we all have friends, families, pets or more importantly boats that deserve our attention rather than this thread. I get the feel of planing thing from Doug but it is not normal if the hull requires to load most of its weight onto an ama to plane. That is not typical planing like we are used to in sailboards and dinghies. It would be nice of I could offload half of my Lasers displacement onto a nice thin hull so the fat hull could plane earlier.

    I am sure we have all stated our positions and I know CT has better things to do with his time like getting ready for a big day! So at the risk of a bloodied nose I will now withdraw and look forward to the next thread.

    Like why is there no data on structures for amateurs? or Should old designers give out their secrets when they retire? Could we all reverse engineer a heap of multis and put all their data on a central database? There must be more good topics out there.

    cheers to all

    Phil
     
  14. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Unsupported assumption!
    After 25 years of spending nearly 20 hours a day together, my wife has left me. (For three days.) :p

    I'd be happier if we could actually put some numbers on the dynamic forces that affect displacement hulls so that we have something substantial on the table. (Unlike the thin gruel I just made myself).

    Leo.
     

  15. Paul B

    Paul B Previous Member

    Looking at that fine craft I would guess your planing design planed as well as your foiler foiled!
     
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