Solid metal hovercraft skirts

Discussion in 'Boat Design' started by rubenova, Jun 23, 2017.

  1. rubenova
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    rubenova Junior Member

    I've been looking all over the internet for a barge hull design that would use it's shape instead of flexible skirts. The barge would be operated in water only and be able to rest on a muddy bottom between tides. I was thinking of a flat bottom with half-pipe shaped protrusions around the perimeter that would trap the air and act as the skirt. Does anyone have any modern or historical examples? Ideas and opinions are welcome. Thank you
     
  2. Barry
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    Barry Senior Member

  3. rubenova
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    rubenova Junior Member

    ....I didn't see any with solid skirts...
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    There are "sidewall" surface effect craft, which are partially solid skirts, the entry and exit ends being flexible in some way. It certainly would also be possible to have three sides with rigid "skirts", the exit end would likely need flexibility.
     
  5. rubenova
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    rubenova Junior Member

    Thanks Mr Efficiency. 3 out of 4 isn't bad! I'm curious about the exit likely needing flex. Please continue with your thought. I am very interested in eliminating flex for the sake of durability in beaching. Even at the expense of drag during travel.
     
  6. Barry
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    Barry Senior Member

    There are quite a few of this type of craft that have been built, most unsuccessfully. If the plan is to have the round tube on the sides hold the air back, you could consider instead a flat plate that will always be immersed to limit the amount of air that can get out the sides.
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    You certainly won't be able to use a vertical or near vertical wall at the stern, especially in a lumpy sea, with large volumes of entrapped water, and get any sort of speed beyond a crawl. Take into account, too, that your sidewalls will need buoyancy to maintain stability of the craft, something elevated by air pressure alone won't be stable. A slim wall with little buoyancy would not work.
     
  8. rubenova
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    rubenova Junior Member

    Flat is a great idea. Simplifies construction compared to rounded. Do you have examples of the failures? I like to learn from examples successful and failure alike.
     
  9. rubenova
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    rubenova Junior Member

    Thank you Mr Efficiency. This is exactly the type of conversation I was hoping for. Speed vs stability vs durability. Would a rounded protusion instead of a flat reduce drag? Maybe a combination of flat sides and round forward and aft?
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    The thing has to be stable, not create great drag ( especially a problem as speed increases), and seemingly the solution offered by rigid catamaran like sidewalls with hull opening ends that are free to more or less follow the undulations of the water, by some contrivance or other, offers a solution. Needless to say, the economics and general practicality of applying large amounts of power to maintaining pressure with leaky ends, is a headache. If it was easy, it would be more widely used.
     
  11. rubenova
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    rubenova Junior Member

    Very good points. I'd like to take a variable or two out of the equation. I'd like to emphasize stability at rest and minimize travel speed factors. Or a design that travels in deep water without hovering? (hovering only in the shallows). Again, thank you for letting me ask these questions and hearing your comments.
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    The appeal of hovercraft is their ability to travel over both water and land, or at least in the case of a sidewall, to get into shallower water than a catamaran of similar dimensions. There seems little sense in having a hovercraft that is slow and does not enjoy the benefits of being able to run up a beach or into shallows. What possible advantage would such a craft have over a barge ?
     
    kerosene likes this.
  13. rubenova
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    rubenova Junior Member

    I completely agree. There is an interesting thing that happens when comparing multi-tasking and uni-tasker. By reducing a single strength of a machine to enhance the remaining weakness's... the usefulness narrows. My goal is to explore how far I can go with a design to enhance a few criteria at the expense of others to see if an idea will work. I like everything about a hovercraft except the flexible skirts. By eliminating the amphibious aspect of a hovercraft, and minimizing speed potential of a barge I hope to have a vessel that is stable at rest and able to go inland on a high tide and rest on the beach at low tide. I like to compare this idea to a couple of cars. A Toyota Corolla is the most basic, reliable way to get from a to b. It does not do anything one thing extraordinarily, just consistently and day after day. Compare this to an old American muscle car that only accelerates. I'm a fan (and owner) of both. My barge will be at the dock until I retire, then going (slowly) from bay to bay to Alaska after that. The replies have been awesome!
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    Hovercraft are very much specialized vehicles, that have limited applications. The thing they do that sets them apart from boats, is the capability of leaving the water and moving over dry land, it is an attribute that comes at the cost of lots of power, unless you absolutely must clear the littoral zone, there seems no reason to dally with them. One good application I saw was a small one used by professional worm diggers who were able to travel lengthy distances over mud banks quickly to reach the desired spot for digging, and spend more time at work, during the two or three hours available before the water rose rather than spending scarce time trudging back and forth through the bog.
     

  15. tspeer
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    tspeer Senior Member

    The first hovercraft did not have skirts. A good example is the Saunders Roe SRN-1.
    [​IMG]
    They used a high-velocity peripheral jet to make an air curtain that captured the air cushion. However, this is far less efficient than flexible skirts.
     
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