Single pontoon boat drawing

Discussion in 'Boat Design' started by Saqa, Jun 15, 2021.

  1. Saqa
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    Saqa Senior Member

    I don't know. That's why I said "if superior". Educate me please
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    I would think an air fan could easily be damaged by "solid" water, always a risk in open water, but I'd say there would be other drawbacks as well.
     
  3. Saqa
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    Saqa Senior Member

    Me E, the way you worded the question made it appear that you knew but were testing to see if I did. What gives?
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    No, but it is the first thing that came to mind, you have hovercraft of course using air fans, so maybe I am wrong. Noise would be a deterrent
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    I am tipping commercial hovercraft have special props that can deal with open water and the possible ingestion of solid water, your swamp boat probably not
     
  6. Saqa
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    Saqa Senior Member

    I know they aren't built as strong as a water prop, as that medium is denser. How do you factor surface use of air props on water, especially those in commercial use e.g. seaplane, flying boat, WIG, airboat. I am sure most of these would travel for some distance on water at over 30 knots before those that take off, do. If the nature of these things were that fragile, then these vehicles wouldn't be used for carrying passengers

    Again, I am only taking my clues from observation and do not claim to know what I am talking about

    Lol, some concern right now:
    Does an air prop need a more powerful engine than a water prop to propel the same craft at 30 knots?

    If not, does an air prop need more rpm, can the same engine run higher gearing? Or does it suffer as gearing higher reduces available power to the prop

    Not too much concern about this right now, as can be easily model tested in the near future
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    The sea going hovercraft would be the applicable analogue, seaplanes typically are configured not to have propellors in harm's way of solid water
     
  8. Saqa
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    Saqa Senior Member

    True, rear fan location would be around the same zone as the RIBtoon
     
  9. Saqa
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    Saqa Senior Member

    I have been reading up all night about air props and I think I will stick to a water prop while compiling this concept. Means getting rid of the tail area and lowering the skeg to take a prop shaft

    Does anyone have any recommendations as to how the prop should be configured under the boat. I have never looked going inboard like this before on a planing vessel. Do I do a skeg transom like this pic and dress it with the SE300 foil and with prop underneath?

    [​IMG]sil003
     
  10. bajansailor
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    bajansailor Marine Surveyor

    You seem to be gradually metamorphosing into a more conventional type of hull form now..... ?
    Do you really need a skeg?
    Many planing boats with inboard shaft drive engines don't have them - you could just have the prop shaft supported by a strut.
    And you could have a tunnel in the transom to recess the prop into, if you are worried about draft.
    Heck, you could even start looking at surface piecing propellers.
    Or even build something like a Thai 'longtail' ?
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    A good thing the air prop has been "retired" from saqa's ambitions, the whale watchers would be up in arms about the noise upsetting the whales !
     
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  12. Saqa
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    Saqa Senior Member

    That green hull is something I drew up years ago for use in another country. Still sticking to the alloy pontoon as it appears to be a good structural member (pun intended), and I am totally over punishing myself with a grp build bigger than a little boat

    Have a look at this pic

    [​IMG]Rooster015

    See how the transom has a pair of tunnels separated by the keel.
    Those tunnels extend to the bow. They are for energy regaining energy experiments. Energy from motive force throws up water at the bow on most fast boats. That water is accelerated mass, isn't it? But that is an added value feature and I will leave that to explore more another time

    The highlighted circles are 4 hard points. The first point is at the bow behind the blade as in initial pics and the back three points are at the transom

    The concept needs a foil at the forward hard point (leave that for another time, as that will be an active system chasing its own sub concept). I want to try to have the outside pair of hard points acting as stabilisers while on the plane

    Bajansailorman, you might be right, I might not need a full skeg. But will need to get the prop lower than the outside hard points

    Keel Hard Point (rear)
    Foil vs pad situation here, needs to maintain plane and keep the stabilisers just skimming along. I do not know which way to proceed here. I guess will need a faired nacelle to hold the prop in the first place. The V keel fabrication can double up as prop shaft conduit and exhaust line, even the prop, if I give it a skegy profile at the transom

    [​IMG]Rooster017

    Any recommendations here?

    There you go again! Do I really need more ideas chasing each other in my head??!! :D
    I'll draw a centre line that has the tunnel pair flowing into a single tunnel, giving a cat look at the transom. Shorten the V fab up, stick out a large enough dia shaft that doesn't require a strut in that bigger tunnel. I'll convert those outside hard points into integrated planing surfaces. The lower edge of the transom will look like the ohm symbol

    Polystyrene models with RC hardware could possibly help
     
    Last edited: Jun 16, 2021
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    The road safety ads used to say "speed kills", and it sure kills fast boats with little ability to reduce wetted surface area, drag just grows like Topsy as speed increases. Concentrate on reducing wetted area, if you must go fast
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    After seeing that musical instrument you intricately carved, I thought this might appeal....

    091624ea09f2c50b21ec99cf20053077.jpg
     
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  15. Saqa
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    Saqa Senior Member

    Did you have to do that! Now I will build it!!, and with STYLE!!!!!

    What's your thoughts? Planing pads or foils? Would I be right in saying foils would have less drag than pads? Then it will be only weighing up the safety side of hitting things where the pads would be safer
     
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