Gimbal Cabin?

Discussion in 'Boat Design' started by stonedpirate, Sep 23, 2011.

  1. stonedpirate
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    stonedpirate Senior Member

    Had a brainwave this morning and was wondering if anything like this exists.

    Have been designing a long distance 10 foot cruiser and most peoples critisism is that it will be so uncomfortable like being stick in a washing machine.

    How about a cabin within a cabin, so the outside cabin moves with the water but the inside cabin rotates on all axis and remains level.

    It would eliminate interior motion.

    Anyone seen anything like this before?

    Thanks
     
  2. BMcF
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    BMcF Senior Member

    The Japanese created a demonstation vessel some years back that incorporated an actively-stabilized passenger cabin, suspended on hydraulic servo-actuators above the hull. As long as the motions being removed were within the range of the active suspension system, it was a neat science project. After the ranges were maxxed out and stops reached..not so much.

    A passively gimballed/suspended cabin...a potential for disaster IMHO. The likelihood that the cabin motions will well exceed what the hull motions would otherwise have created is quite probably under some sea conditions..
     
  3. stonedpirate
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    stonedpirate Senior Member

    thanks B.

    I was thinking of a sphere within a sphere sepeated by ball bearings.

    So it would roll around effortlessly regardless of how fast the hull was moving.
     
  4. daiquiri
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    daiquiri Engineering and Design

    KISS principle is always a better option, imho. Any mechanism of the type you have described would:
    1) introduce moving parts subject to wear and glitches
    2) greatly increase manufacturing costs
    3) increase maintenance costs
    4) increase vessels displacement, and hence fuel costs
    5) increase vertical CoG position, and hence decrease vessels stabilty
    6) even in case it works, could give a false impression of safety because accelerations and roll angles are an important safety feedback for helmsmans decisions and actions.
    Etc.
     
  5. rwatson
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    rwatson Senior Member

    This concept was tried on an English Channel Ferry back in the 1800's.

    The large 'main cabin' was suspended on bearings, so that it could remain vertical, even if the rest of the boat was rolling.

    The 'cabin', developed its own momentum, and swung back and forth independently of the boats main hull, flinging the passengers around wildly.

    They tried the trip a second time, with a 'brake-man' who could apply a damping system to this pendulum effect of the main cabin.

    Unfortunately, it wasnt able to be controlled sufficiently, and the boat was converted to a standard ferry.

    If you build a scale model, I suspect you will find that the central 'pod' will develop its own momentum, which will be much wilder and more uncomfortable than that of the boat itself.
     
  6. BATAAN
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    BATAAN Senior Member

    A ten foot boat with a gimbaled cabin? How do you get in/out when the boat is being flung about? Stupid idea, but I'm prejudiced having spent too long at sea with real problems. Please draw a picture for yourself and imagine actually using it. Kind of like a ball turret on a B17 in size, adds lots of weight, always off balance if you move your arm unless heavily ballasted, in a ten foot boat? I want what you smoke.
     
  7. daiquiri
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    daiquiri Engineering and Design

    Oh, it's a 10 ft boat? I have missed that particular... :eek:
     
  8. Jeremy Harris
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    Jeremy Harris Senior Member

    Not at all easy to do, as others have already pointed out. The big, really big, problem, is momentum. You simply won't get a gimballed mass inside the boat to remain stable. I learned this years ago when a student. One of the legs broke on the bed in my room. Being an engineering type I got some steel cable and suspended the bed from four wires attached to ring bolts in the ceiling beams. Not a good idea, especially after a few beers (even worse idea for anything that involved movement in bed.....). Goodness only knows what it'd be like on a small boat.
     
  9. Milehog
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    Milehog Clever Quip

    It sound like a good way to get seasick and-or injured.


    You ask, does he mean the gimbal scheme or the 10' boat?
    The answer is yes.
     
  10. BATAAN
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    BATAAN Senior Member

    Gimbaled Captain's bed in whaleship CHARLES W MORGAN at Mystic Seaport. Due to the slow roll of this 400 ton ship, the Captain's wife could sleep level on this bed.
    The saloon tables in the 80' schooner WANDERBIRD and 70' ALCYONE are also gimbaled, with hundreds of pounds of lead for ballast. Don't get your finger caught, but things don't slide off the table.
     

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  11. BATAAN
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    BATAAN Senior Member

    Also, you can see the ballast box under the Captain's bed. Lots of lead, lots.
     
  12. CatBuilder

    CatBuilder Previous Member

    I like the gimbaled bed there, but I would post the same thing as Daiquiri.

    Also, I'd add that the noise of the rolling ball bearings would drive you insane at sea or at anchor trying to sleep.

    That and that all of this is absolutely impossible in a 10' boat. What's the headroom like inside the "cabin" of a 10' boat? I know canoes longer than that. You'd be laying down in the thing anyway.
     
  13. BATAAN
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    BATAAN Senior Member

    Won't work on a ten foot boat but worked fine on the MORGAN. Of course they only gimbaled the bed, not the cabin.
     
  14. alan white
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    alan white Senior Member

    Small hull envelope... to frame any stiffness into the hull you would lose space as the area between frames would be unusable. Then a clearance gap and the inner "hull" with its own structure. More like a seven foot boat now. I'd rather suffer the motion than the lost volume. A simple hammock is a better idea. In a small vessel, the hammock is never in the way when not in use.
     

  15. Tad
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    Tad Boat Designer

    Gimbaled tables used to be common, Chichester had a gimbaled chair in Gipsy Moth IV and perhaps in V as well. In 1985 I designed a gimbaled sit-in galley in a 60' aluminum cutter for the first BOC race.....wacky idea......it was to have ballast and an elaborate cam lock system to slow it down....no one noticed.....

    Gimgalley.jpg
     
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