Mud and the Tender

Discussion in 'Boat Design' started by rwatson, Aug 25, 2012.

  1. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    In my mind, sailing, rowing are not necessarily the problem with Sealegs, I just dont think a trike will get across sloppy mud. It will need support from the hull, and the wheels will just sink out of sight.

    Also, by the time you work out the motorised drive for the raising legs, the weight, complexity and complications mean .... I might as well just buy a Sealegs, and still not get across mud. Also, you would need a big yacht to utilise sealegs as a tender.

    Cleats on the side of tyres are a good idea, but they reduce the positive flotation of the tyre, as they restrict the width of the tyre if you want to keep the wheels inside the hull. They also dont provide any 'hull raising' effect as they rotate.

    The total 'envelope' size of the tender has to be kept as small as possible to make it 'deckable' on an average yacht.

    I'm putting a lot of restrictions on the solution by keeping it small and manpowered, because the problem has been solved many times if engines and size are not limited.

    heck, what I really want is a huge seagoing amphibian that doesn't need a tender, but until I win the lottery, small will have to do.
     
  2. portacruise
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    portacruise Senior Member

    RW:
    Good to hear you are making progress for your specific situation, whereas I have been thinking in more general terms...

    Yes, I also think Sealegs would get stuck in the mud. But the concept, as applied in the smaller water trike would not, since it floats and propels in less viscous water compared to mud, under HP. Shallow mud slippery bottoms would require regularly spaced deep cleats, something inspired by your cam wheels (Why do you need 'hull raising'?). Only 2 modified water trike flip up/down/removable wheels are needed, carefully positioned to avoid teeter-totter near the center of mass at the sides of the boat. They would run without the wobble of cam wheels on dry land to allow completely mudless transfers. In the flip up mode, they don't intrude into a crowded 3 person interior area, or introduce deep water cruising drag from a carved out compartment. If swung around to the proper position, they would not interfere with oars, sails, or even motors. This would me my needs anyway.... How to do a HP transfer to wheels while allowing for swing up- have absolutely NO IDEAR !!

    Thanks for your interesting ideas and feed back.

    Porta


     
  3. rwatson
    Joined: Aug 2007
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    rwatson Senior Member

    Thanks Porta.

    I may need to revisit your suggestions if i cant get my 'simple' method to work. Getting moving metal bits engineered and manufactured is complicated and expensive.

    Call it cheap, but I tend to prefer trying less expensive methods first :)
     
  4. Village_Idiot
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    Village_Idiot Senior Member

    Here, I'll post it again...

    http://www.rcmania.com/reviews/tyco-shell-shocker/

    If you could build a large heavy-duty version of this, it would serve as balloon tires in the mud, and paddlewheels in the deep water. Design and build it right, and you may have a market (assuming the idea isn't patented...).
     
  5. portacruise
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    portacruise Senior Member

    VI:

    Thanks for posting the interesting gadgets.

    Here's a more stable version of a similar idea which the military is evaluating:

    http://www.engadget.com/2012/08/11/darpa-captive-air-amphibious-transporter/

    "I'm putting a lot of restrictions on the solution by keeping it small and manpowered, because the problem has been solved many times if engines and size are not limited." RW

    As RW points out just about anything is possible given a large on board energy source to drive it. Converting these to HP, and still having room for 3 occupants while being light enough to pull into a yacht would be tough issues to surmount.

    Hope this helps.

    Porta

     
  6. Village_Idiot
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    Village_Idiot Senior Member

    True. I guess I was thinking of utilizing a small engine (<20hp?). Geared down, it should have plenty of power for moving across the mud - you only need one axle, slightly ahead of the longitudinal CoG. Certainly small enough to be hoisted onto a yacht. But powered, nonetheless. I suppose you could devise a pedaled version with low enough gearing...

    Cool marsh buggy! Wonder how it would fare in sand (the nemesis of most marsh buggies)? Thanks for the link!
     

  7. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    Thanks Porta, for the recognition of the design brief.

    Despite much of this gear not being applicable to my self imposed SOR, I love to read about these things.
     
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