Hull with the least wake

Discussion in 'Boat Design' started by silentneko, Jun 21, 2021.

  1. tlouth7
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    tlouth7 Senior Member

    But you will notice that even those catamarans make more wake than the vastly longer rowing shells.
     
  2. silentneko
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    silentneko Junior Member

    Well we went down another rabbit hole there, lol. I guess I should have specified I meant out of currently available designs. V-hulls, Cats of various type, flat bottoms, sailboats....
     
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  3. Benjamin
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    Benjamin Junior Member

    Waterski boats are designed to create the smallest wake possible at speed, but they definitely dont handle any rough water well at all
     
  4. silentneko
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    silentneko Junior Member

    Most of the ones I've seen around here are designed for max wake. They even add bladders to the stern to increase it for the skiers and boarders to surf.

    On plane many boats put out smaller wakes, but I'm more focused on displacement speeds. Rough water ability is a separate deal for down the road.
     
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  5. gonzo
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    gonzo Senior Member

    It is. Calculate the submerged volume you need to support all the mechanical systems plus crew, fuel, etc. and you will see that the volume of you "pipe" will mean it is hundreds of feet long. You routinely dismiss realistic assessments by claiming "it can't be complicated". Show us the numbers to your design and how it is not complicated.
     
  6. DogCavalry
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    DogCavalry I aim to misbehave.

    I had assumed you meant displacement hull. If planing boat, then the Hickman sea sled had the lowest wake of any planing form. At a given displacement speed ratio. The lack of wake is the reason for it's other advantages. Or it's other advantages also lead to minimal wake.
     
  7. silentneko
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    silentneko Junior Member

    No, I did mean at displacement speeds.
     
  8. DogCavalry
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    DogCavalry I aim to misbehave.

  9. Saqa
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    Saqa Senior Member

    I have some experience in the actual fabrication part of a pipe like that. It's not that different from building an MDF transmission line. The only real difference is the glass skins and PVC foam instead of MDF. Previous transmission lines were done before I started using composites. Using kerfing to slit up the MDF and wrapping it on a stormwater pipe section is how I did them. School holidays are coming up next week. I think it's an excellent experiment with my kid. A pedal powered beach toy would be cool, and we will try some homemade impellers inside the tubes. We will use XPS as the build material and method will be strip planking on cardboard tube formers that can be wetted and removed after gluing. Flat glass/XPS deck over the tubes and bask in my speedos with feet on a pair of pedals

    We will make bundles of strips to see how many we need to float us clear out of the water before forming them into tubes

    Please do not call it routine dismissal, as I offer a practical means of implementation. Please do remember that the question was open ended, "Hull with least wake"

    And also keep in mind that I raised the ducted hull as an idea that I thought has a chance based on intuition to an international boat design community and asked those in the know how they think it might behave

    "Just a random thought, I get this image of a hollow tubular hull with a scoop opening in my head. If all the water being pushed aside by the nose gets pushed through, does it still create as much of a wave"

    You actually are not picking on any of the actual outright dismissals of the concept, and have not even tried to offer an answer as to dismissals like

    "More likely the resistance would increase....."

    "Be gnarly wave interference inside that pipe, to say nothing of wetted surface area."


    Are you actually calling requests to elaborate routine dismissals too?
     
  10. Dolfiman
    Joined: Aug 2017
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    Dolfiman Senior Member

    At relatively low speeds and without draft constraint, it is the SWATH, the deeper the hulls the better :
    Small-waterplane-area twin hull - Wikipedia https://en.m.wikipedia.org/wiki/Small-waterplane-area_twin_hull
     
  11. Robert Biegler
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    Robert Biegler Junior Member

    If you are thinking about a catamaran with the outsides of the hulls straight and parallel, the insides curved and funnelling water towards the middle, where you put the engine to suck it through, then you let the insides of the hulls open up again to canoe sterns, and if you enclose all this by a plate connecting the two hulls, I suppose that would get rid of waves caused by water getting displaced. That opinion may not be worth much, seeing that I am not a physicist, much less working on fluid dynamics. You would still affect water beyond the cross section of that hull and tunnel by skin friction. You would also have a large wetted surface area, so I don't know whether such a low wake hull would have less drag than just a plain catamaran. And I don't know how this would deal with waves, when the amount of water being fed into the tunnel would vary.

    Apart from the very slender hulls already mentioned, there is also the option of trying to generate wave trains that cancel each other out. Examples I can think of are the Displacement Glider, some trimarans with the amas placed in the troughs of the centre hull's wake (as I understand it, that cancellation occurs only within a narrow speed range), and Calderon and Maskew's Transonic Hull (Transonic Hull: Theory, Validation, Breakthroughs and Applications to Ships | SNAME International Conference on Fast Sea Transportation | OnePetro https://onepetro.org/snamefast/proceedings/FAST15/2-FAST15/D021S005R005/461517). I don't understand the mathematics justifying the transonic hull, and I can't think of an intuitive approximation for why it might work. The claimed empirical data look like there could be something to it.
     
  12. DogCavalry
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    DogCavalry I aim to misbehave.

    The claims made for transonic hull, referred to in the previous post, seem implausible.

    But the patent has expired. It would certainly be cheap and easy to build and test.
     
  13. Iridian
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    Iridian Junior Member

    You guys are making this too complex. Hydrofoils have a really really low wake. Stay on the foil and keep the motor deep under water. Could probably get close to 30 kts with a reasonably low wake with a strong enough engine.
     
  14. DogCavalry
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    DogCavalry I aim to misbehave.

    Lol! You suggest hydrofoils, but think we are complicating things. The only thing more complex than hydrofoils might be a hovercraft.
     

  15. Skyak
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    Skyak Senior Member

    Hovercraft.
    Or WIG craft.
    I win! ;)
     
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