Vessels with suspension

Discussion in 'Boat Design' started by JonathanCole, Apr 17, 2008.

  1. Guillermo
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    Guillermo Ingeniero Naval

    Present 'suspension' vessels.
    Stephen, what speed are we talking about?

    Cheers.
     

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  2. kach22i
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    kach22i Architect

    I keep catching myself thinking in single or two directional forces, rather than 3D forces or forces over a period of time.

    How would a chamber of air under the cabin dampen the vertical acceleration (in the UP direction)? Would not the air chamber be better if it were a sphere around a sphere or operated as a gyroscope?

    Tethers?

    I also keep thinking that jet aircraft style "G-suits" which keep blood to the brain may be able to play a role, but have no science or research to back up that random thought.
     
  3. warren mosler
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    warren mosler Junior Member

    suspension

    Applying my automotive experience to displacement hulls:

    The water already acts as a spring, and the hull shape determines it's rate of increase as it moves vertically.

    damping could be done by underwater horizontal 'ridges' but with a drag penalty.

    The ratio of sprung to unsprung weight determines the degree of ride control in a simple spring/shock setup. This is the awkward part for a boat, as simply suspending a seat is totally backwards in this respect, for example.

    In a car or truck, there's no substitute for wheelbase for ride quality. In this respect a boat hull is like a snow board going over a bump vs a skate board going over a bump.

    To replicate the ride of a long wheel base car would require a boat with the floatation fore and aft, with as much 0 floatation in between as possible.

    This has other issues, such as getting sufficient displacement with a reasonable draft and reasonable length to beam ratios. Seems impractical for most missions.

    Best I can think of is something like two displacement power cats in tandem with a long deck maybe 8 ft off the water line separating them with the cabin on it.
     
  4. yipster
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    yipster designer

    Guillermo, pic 5 in post 10 is a SWATH ride yes ?
    [​IMG]
     
  5. warren mosler
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    warren mosler Junior Member

    suspension

    Yes, does what it does reasonably well, same with 4 hull 'slice' which rides a bit better, i'm told, due to the 'long wheelbase' effect i describe above, maybe.

    both forms have deep drafts and relatively high drag at speed, with speeds above 20kts problematic, also due to propulsion issues?

    Anyone seen a 'four footed' surface craft? The 'stability yachts' prototype moves some in that direction but doesn't try to max the 'wheelbase'?

    http://www.stabilityyachts.com/
     
  6. kach22i
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    kach22i Architect

    An old post of mine (Hovercraft):
    Mar 29 2007, 02:29 PM

    .............................................................................................


     

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  7. yipster
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    yipster designer

    computer controlled thats all very well possible kach22i
    saw a mountain climber car in an old popular mechanics once like in fig 5
    looking from the top i wonder why there are no whisbones used
    samples are older and for a hoover patend spider i'll bet it only cost ya
    but thanks for showing, nice one i missed before :cool:
     
  8. yipster
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    yipster designer

    [​IMG]
    and Warren, how much i like stabilityyacht (and swath) i'll keep thinking of wanting a sail...
     
  9. rambat
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    rambat Member at large

    Hydroshock Therapy

    Yipster, I am the designer for Stability Yachts"yacht version", thanks for your kind words about the prototype craft. It is possible to make it sail propelled and could be considered since the drag is like a catamaran when pumped up, Hmmm.
    Interest has been strong with the recent press we have garnered around the new Stability 63 yacht, If we get a deposit to build it I will probably pour any profits into research for other better riding craft, especially small-high-speed craft. Years ago when boats started going to fast for safe human factors I was thinking about something like the Longbow concept attached. It may be a small concept, like a rough water dirt bike. In larger designs this could take advantage of the "flexibility" in the structure, like the aero elasticity in jumbo jet wings. That flexibility may allow the hard points on the shock absorber to stay attached. Way fun riding I am sure! Great concept Kach, I have a "Cache" of old concepts from Bell Aero with some offshore stability ideas for hovercraft, when I get time to scan them I'll post them here.
     

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    Last edited: Apr 28, 2008
  10. kengrome
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    kengrome Senior Member

    There are simpler ways to reduce vertical acceleration in boats, it's just that the buying public doesn't like the looks of such boats ... and/or the designers and builders of today choose to ignore the proven techniques of the past.

    Take a look at the Seaknife designed several decades ago by Peter Payne:

    [​IMG]

    Mr. Payne was a genius mathematician (http://ourworld.compuserve.com/homepages/graeme/Peter/prpatent.htm) who understood how to make a high speed planing hull that substantially reduces the vertical accelerations that injure people. The boats plane on narrow flat triangular bottoms and their bows are so sharp that they slice smoothly into waves as they meet them, dramatically slowing the boat's vertical acceleration compared with virtually all other planing hull boats.

    [​IMG]

    Maybe it's time we took a look at the past, and use the simple solutions proposed decades ago, instead of complicating everything with the typical high-tech solutions of today.
     
  11. kach22i
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    kach22i Architect

    I've seen the SeaKnife posted in these forums before, but never quite in this context or certain perspective.

    Cool contribution.
     
  12. kach22i
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    kach22i Architect

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  13. CaptBill
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    CaptBill CaptBill

    How about a moon pool suspension system? You get as bonus features 1.generator (piston driven) 2. air conditioner 3. Dampening suspension. Super simple and potential for no moving parts (designed as a simple an 'air pocket' under the water line).

    Noah's Ark appears to have had this feature.
     
  14. kach22i
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    kach22i Architect


  15. CaptBill
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    CaptBill CaptBill

    The idea is simple.

    Cap the hole in the moon pool at, say, deck level. Now massive amounts of air pressure/suction is collected in the hole. The weight of the hull as it rises an falls with the waves creates a constant compression/suction force.

    The idea is to collect the energy in a hydraulic system . When you are 'consuming' this energy you will have a dampening effect because the relative height of the piston (water level) is being slowly 'deflated/inflated', creating a dynamic alteration in the motion.

    Amazingly simple concept.
     
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