Power for foiler

Discussion in 'Boat Design' started by Saqa, Jun 22, 2021.

  1. Saqa
    Joined: Oct 2013
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    Saqa Senior Member

    This is not a design, but just an idea, a thinking exercise and distraction. Probably will never get built

    Trying to think up a wide bay crosser that has a 30knot cruise with around 200km range. Only for fairly good days, there is a safer but longer return path if the weather changes

    I redrew the RIBtoon idea. A single 3mm wall aluminium pontoon 20' length and 70cm dia wearing fore and aft inflatable fairing and surface piercing foils. Striking objects in the water is a concern here, so there will be some addressing of how the foils are implemented as I evolve the idea. The pipe will be inserted in the skirt and most of the skirt will come up to the widest part of the pipe, leaving most of the top exposed

    Pontoon to have bulkheads separating an engine bay, cockpit cutaway, reserve volumes. Craft needs to accommodate use of 4'ish butterfly jigging outfits over the gunnels

    Pics are to illustrate the idea and in no way a complete buildable design

    The inflatable part, 26' with 1.8m beam

    [​IMG]Leghorn001

    [​IMG]Leghorn002

    [​IMG]Leghorn003

    [​IMG]Leghorn004

    [​IMG]Leghorn005

    [​IMG]Leghorn006

    Illustration of the pontoon and drivetrain setup. Foils not shown

    [​IMG]Leghorn008
     
  2. Saqa
    Joined: Oct 2013
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    Saqa Senior Member

    I think I have come up with an elegant way to implement an outboard with a full foiler utilising the functionality the outboard offers.

    It depends on a few conditions though that I have to look into more. I need to find some pictures that clearly show an outboards internal drive train. Preferably Yamaha or Mercury and exploded views (mine is an Evinrude). Also need to speak to an outboard mechanic

    Trying to find a way to tap the still spinning crank shaft when the rest of the outboard is in neutral position, and then being able to up throttle while the leg is still in neutral. Accessing the flywheel might work. I really need to discuss this with an outboard tech. In the meantime, I'll do a drawing of the idea as time permits

    Any guesses as to what scatterbrain idea I have now?
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    The drive shaft is always turning right down to the pinion gear in the gearcase, when the engine is running
     
  4. Saqa
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    Saqa Senior Member

    Is it possible to change the ratio or have a one to one ratio?
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Off the prop shaft you mean ? The pinion is turning the same revs as the engine.
     
  6. Saqa
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    Saqa Senior Member

    I mean the prop to engine rpm ratio
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    No. you will not get that
     
  8. Saqa
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    Saqa Senior Member

    I just spoke to a local outboard tech. He says there are some ways to do it, he'll think about it and call me back. He also confirmed that the mods I am thinking of are totally feasible and already being carried out on local pro boats to a certain extent. I'll make a drawing and show what I am talking about
     
  9. Saqa
    Joined: Oct 2013
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    Saqa Senior Member

    Ok, my scatterbrain idea for using an outboard with a full foiler. I don't know if this has been done before. I spoke to two marine mechs today, who confirmed that they carry out a similar mod for the local pro boats for hauling up crab pots. They attach some sort of hydraulic drive and clutch to the top of the flywheel. Water pickup needs to be relocated, but that's no drama, they said ;)

    I want to tap the end of the crank at the flywheel to rotate an air prop fitted to a modified cowl. Everyone keeps discouraging inboards and recommending the off the shelf functionality of an outboard without actually suggesting a direction to look to implement it with a full foiler. This idea uses the outboards steering function to steer both props, trim both props. Removes the need for an air rudder, flaps and things

    According to the mechs, the crank can be extended up, just need to find a suitable 90 degree box. A strong enough flex shaft will do the job too. Difficulty is finding a strong enough box or flex shaft. Flex shaft and clutch from a powerful brush cutter can do the job on a small engine. One suggested modifying and using bits from an outboard gearcase for the 90 degree plus clutch. He'll get back to me next week after looking up some stuff

    [​IMG]Leghorn009

    [​IMG]Leghorn010

    [​IMG]Leghorn014
     
    Last edited: Jun 24, 2021
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    All sorts of things are possible if you throw enough money and effort into it, the first thing to note would be that any warranty on your engine would be voided by such alterations, But that may not be a problem with an older motor, but you would need the "luck of the Irish" to have this work without encountering a major hitch.
     
  11. Saqa
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    Saqa Senior Member

    I have to go checkout some of these crab pot lifter mods in person

    Question to anyone who might know. My understanding is that an air prop doesn't need to be as powerful as the water prop in this application. That the thrust required from the air prop to fly the already planing hull doesn't need to be as powerful as the thrust required from the water prop to bring the hull on plane. Is this correct?
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    How did you arrive at that conclusion ? Resistance has to be overcome by thrust, you might be thinking the higher line of thrust will act against squat ? Probably so
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    And how are "we" dealing with water ingestion with the air prop ?
     
  14. Squidly-Diddly
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    Squidly-Diddly Senior Member

    Seems like a 1 meter jacking plate with a couple stout rails and a few small steel wheels would work. Maybe raise/lower with motorcycle chain and geared down electric motor and means of locking chain in place. The chain would be full loop so one pin would lock it up/down.

    SolidWorks full powered Student Edition costs about $99/year you just gotta find someone enrolled in ANY 2 or 4yr college. Its the full program just can't export files to full Lic version or CAM machines, but CAN print out all the blue prints, do real time stress, temp, flow, etc. That can be you taking summer Weight Training PE class at local Community College (plus student fees, etc)
     

  15. Saqa
    Joined: Oct 2013
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    Saqa Senior Member

    Hey man, I am currently doing a course to get some qualifications in working with the elderly and disabled as I am setting up a couple of hire boats in an area very popular with retirees. It's a 6 month course only though

    My prettier half doesn't mind the idea of buying the full version, but it seems we need a professional email address just to ask for the price?!!

    A giant jacking plate could potentially get the job done. I think SolidWorks can aid in simulating one and working out the weights and stress and comparing with simulations of other solutions like going inboard and such

    Hull resistance overcome by waterprop thrust to point of hull planing where air prop kicks in and overcomes the foil resistance..... from what I understand in learing more about air props, they are effective on rolling or sliding vehicles. Which means they can get away with less thrust as pushing through lesser resistance. Such is my understanding

    What do you think?

    That depends of what water ingestion means? Or what part you see that can potentially eat water?
     
    Last edited: Jun 25, 2021
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