What is world's biggest planning hull boat and how fast?

Discussion in 'Boat Design' started by Squidly-Diddly, Sep 16, 2020.

  1. brendan gardam
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    brendan gardam Senior Member

    one thing his paper does not discuss is collisions. imagine hitting a semi submerged sea container at 100 knts.
     
  2. Olav
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    Olav naval architect

    I reckon that's why it's called "technical feasibility..." and not "is it sane to go 100 knots?"... :D
     
  3. brendan gardam
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    brendan gardam Senior Member

    ok
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    It is the wave train that is parallel to the direction of travel, that creates the "hull speed" trap, where the crest of the wave falls behind the stern, then the bow lifts, and the resistance rises with the increased trim angle. People talk of boats "pulling up a big stern wave", but that is because the second crest in now well behind the boat, the wave train obeying the physics of wave train speed and distance between crests. The submarine when surfaced, is subject to the same principle.
     
  5. brendan gardam
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    brendan gardam Senior Member

    i agree but a sub must displace an amount of water equal to its size when it moves, so at speed there has to be some sort of wave action or turbulence.
     
  6. BMcF
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    BMcF Senior Member

    We were involved with the "Moonraker" build and trials. Under ideal (calm) conditions she could manage 60 knots but if there was even a hint of a wave the ride was jarring. The few times we fired up the turbine and went "all out", all the shelves in the pantry had to be cleared and contents boxed..bar cleared, lamps stowed, bar stools laid down, etc etc..

    It's been my experience from helping design and build very fast vessels for almost 35 years that the SES is the most sane way to get there. It was that that prompted Tom Gentry to develop a 70m SES design for what was intended to be his next challenger for the trans-Atlantic crossing record.
     
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  7. DCockey
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    DCockey Senior Member

    No waves if the sub is deeply submerged and the water density is uniform.

    The surface waves caused by vessels moving on or near the surface occur due to the difference in density between air and water. Similarly if the water density varies vertically, for example due to variation in salinity or temperature, then internal waves can occur.
     
  8. DCockey
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    DCockey Senior Member

    There is disturbance of the surrounding water as a sub moves, and the boundary layer and wake will be turbulent, but no waves are created without a vertical density gradient.
     
  9. Doug Halsey
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    Doug Halsey Senior Member

    You're right (in principle); a submarine will always have some drag due to wave effects.

    However (in practice) it quickly becomes negligible as the depth increases, as the attached figure from Hoerner's book shows.
    WaveDragVersusDepth.jpg
     
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  10. BlueBell
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    BlueBell Ahhhhh...

    Not a 600 foot boomer: hull speed greater than 30 knots...
     
  11. jehardiman
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    jehardiman Senior Member

    I don't know about everyone else, but there is something about a paper that uses the Gabrielli & von Karman Line that just turns me on.
     
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  12. BMcF
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    BMcF Senior Member

    LOL. We would often plot the particulars of our latest/greatest hybrid, SES etc against that famous line to show how great a job we'd done in besting the accepted norm.
     
  13. jehardiman
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    jehardiman Senior Member

    Yeah, Figure 1 in the paper was fairly interesting with all the "fornicatorium"s in the lower right (high speed for volume but can't carry much), which pretty much sums up their usefulness. I plotted out some other things (PLAN Type 22, a SEALion CCH, and a MK V SOC) and even with weapons, they were pretty close to the lines in among the yachts.
     
  14. mudsailor
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    mudsailor Junior Member

    Maybe, but was on board it in NY and it is/was such a amazing piece of machinery.
     

  15. jehardiman
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    jehardiman Senior Member

    True, but as with a lot of vehicles like this, they are just vanity pieces. They might be bright and shiny and perhaps push on a very small piece of the design envelope, but in the final summation all they are a technical and economic dead end, perhaps just to be a footnote for the new, more expensive, faster boat's photo-op.
     
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