powered foil Cat

Discussion in 'Boat Design' started by Kiwi solar boat, Jun 4, 2016.

  1. Kiwi solar boat
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    Kiwi solar boat Junior Member

    I am starting a new venture. I am wanting to drum up some help to prove (or disprove) the concept.

    The concept is to build a light weight Powered Cat on foils.

    - 13m x 8m Cat hull
    - Wider hulls (to improve accommodation) with a little lose in performance when not on foils
    - 4 retractable foils (the foils are slightly larger than required to compensate for the fact passengers move around
    - Electric drive (probably built in to the rear foil)

    HULL- I am teaching myself to use Orca / Rhino (but in reality I will import a Google sketchup model)
    FOILS- I needed help with foil design (retractable) The trade off, able to hold approx 4000kg-6000kg, but with a larger foil to hold more capacity (as people will move around)

    I dont want to cover too many subjects other than the hull / foils, as these will dictate the remainder of the design ... but if anyone could steer me in the right direction / run some calcs... most welcome
     
  2. Stumble
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    Stumble Senior Member

    Is this a serious project you are willing to throw real money at, or just something to toss around on the Internet?

    First a motor powered foiling cat cannot use electric propulsion, the weight penalty for the batteries is to severe. You are almost certainly going to need to use gas or diesel. Though I would think a diesel electric may make a lot of sense. Just so you can position the generators centrally.

    For a basic design concept take a look at the Gunboat G4 built by Holland Composits. Unless there is a specific reason not too I would start with this as a base. It's an already proven foiling boat with substantial load capacity. But it would probably need substantial modifications due to the difference in sailing vs power.
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    What speeds are you envisaging ? If, as the name suggests, it is going to be solar powered, it won't be going fast enough for foils to be useful to you.
     
  4. kerosene
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    kerosene Senior Member

    the software used is the least relevant question.
    And as said solar+electric power+foils not going to make a feasible concept. You can create a boat that needs to stay on dock to charge for 3 weeks to drive it on foils for 20 minutes. Doesn't make sense. No I didn't do the math now but the outcome from real numbers will be miserable. This is the key compromise and dictates most other features.

    You cannot design hulls or foils in isolation of the boat as a whole thing.

    see below:
     

    Attached Files:

  5. Kiwi solar boat
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    Kiwi solar boat Junior Member

    Hi All
    Stumble, kerosene & Mr Efficiency, thanks for your replies, but see attached videos of electric foiling boats:
    https://youtu.be/ooAAnZIgj8o & https://youtu.be/lBm_SsWUoEs

    Foiling solar power boats have been a reality for a few years, I simply want to increase the size of the boat.

    Also Ion batteries are also much much smaller than traditional batteries (now providing a real change in size of capacity). I would use the 4 - 10 x 5000amp hour batterries in the hulls

    There is also solar powered boats travelling the globe, I simply want to improve on efficiencies by using foiling, see below the boat that has travelled the world completely on solar (I dont want to make it this large tho)
    https://youtu.be/MPGEig9ajjU

    So back, applying the logic of what is in practice, the question of what sized foils is required to hold 4-6 tone in constant plane.
     
  6. Kiwi solar boat
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    Kiwi solar boat Junior Member

    Mr Efficency
    As far as speeds go, I am happy with what ever I get, I did note on the video (https://youtu.be/lBm_SsWUoEs) at 3:20 he mentions the winning foiling boat almost reached 24 knots.... so until I find a foil design to hold 4-6 t I cant size the motor to reach these speeds (personally happy with 12 knots as my 45 ketch only does 7 knots on a good day)
     
  7. Stumble
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    Stumble Senior Member

    I'll have more faith ithe quadrofoil after we get to see some real numbers not just marketing hype. But it has a 5.5kw motor and a 10kw battery. Do you really think that less than a 2hr range at speed is realistic for a 40' boat? Personally I think the quadrofoil is going to be left in the dustbin of history because people will be pissed at having spent all that money on a boat they can only use for a few minutes before it has to be put back on the charger for the rest of the day.

    Now convert that same hull to operate on a gas motor and it's a much more realistic option, with real range, and a very interesting idea.

    Now SolarPlanet did motor around the world, it took almost two years and I think their average passage speed was 4kn, but they made it.

    I am just not sure that a 100'+ boat that has the same passage speed as a 20' sailboat is all that meaningful. It just says it is possible, which everyone already knew, not that it is practical, which it isn't.


    By my definition of practical, the only way to have a practical large foiling boat is with ICEs. Anything else is simply a very expensive engineering proof of no practical value. I will admit it can be done, probably trivially easy with enough money. But the usage parameters of it would be rediculious and I can't see anyone wanting to buy it.
     
  8. Kiwi solar boat
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    Kiwi solar boat Junior Member

    Stumble,
    You know there are races purely on solar right?
    The latest is 40 nautical miles x 3 crew x completely on solar ;)
    Have a look....https://www.youtube.com/watch?v=tNid87rEkeU

    On the foiling front, have a look at this team:
    http://www.solarboatteam.nl/project/

    I am making some assumption and feel free to correct the numbers

    The boat travels in excess of 25 knots completely on solar power, their next boat is even faster!

    But raw data:
    The Solar panels m2- 1.2m x 3m= 3.6m2
    Weight - (driver 60kg, boat 60kg? = 120kg)
    The ratio is= 1m2 Solarpanels can lift 33.33kg @25knots

    If I design a foiling cat 13m x 8m= 102m2
    102m2 x 33.33 = 3466kg @ 25knots

    I dont want to go 25 knots!
    So add some weight (batteries for night running) / drag, but the target is 4t - 6t at approx 12 - 15 knots

    Now I simply need to run the math on different foils
     
  9. Stumble
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    Stumble Senior Member

    Like I said, go take a look at the Gunboat G4. You would need to take the rigging of, and replace it with solar panels, but all the engineering on the foils is already done. You could probably save a few pounds by re-engineering the boat without the sails, so lighter cross beams and the like, but I don't it will save a whole lot.

    G4 all up weight is 2,700kg lightship. Has proven foils, and the molds are already built.
     
  10. Kiwi solar boat
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    Kiwi solar boat Junior Member

    You are right it has most of the principles! Thanks
    2.7t with a max displacement of 4.3t
    It has an additional 1.6t! Thats a huge amount of extra capacity!

    I need the cad design of it. To calculate what drive is required and solar panel space etc

    I wondered if it is little small, but coming from a 45 ketch, even a 39 ft Cat will seem huge.
     
  11. kerosene
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    kerosene Senior Member

    I don't doubt that you can go solar only, but those boats are ultralights.
    These have existed for long also:
    http://sunwindsolar.com/wp-content/uploads/2013/01/SOLARCAR.jpg
    but its hardly a proof of concept for a solar camper van.

    And I am well aware of the solar circumnavigating boat. It makes no sense.

    And don't get me wrong I find all this very exciting - I want it to be possible faster than the development is happening.
     
  12. Kiwi solar boat
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    Kiwi solar boat Junior Member

    Agreed, I am merely number crunching at this stage and planning on making proto types.

    I feel it will always come back to a weight speed trade off with solar power UNTIL batteries are much more economical and solar capture / conversion rates are improved.

    In the mean time I will be happy to make a hull that has the ability to perform in the future. If I have to replace solar cells or replace batteries, I am happy to do this as technology improves.
    Right now, I will look to prove or disprove that a light weight hull can perform, its a math exercise. If it stacks up in computer modelling, I will go in to prototype phase.
     
  13. Stumble
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    Stumble Senior Member

    Well the G4 molds and tooling were just sold at a bankruptcy auction, but I can't remember who got them. I am pretty sure HC (who built the G4h still has physical posession however. I would bet the cost of a new boat that they won't give you the drawings of the boat, but if you are a serious player would be happy to collaborate on building from the existing molds.

    If I remember correctly the cost of a G4 new was about $750k, minus the $100k of the mast and another $100k for the sails. So figure you could buy a completed hull w/foils in the $500k range. Obviously rough numbers, but in that ballpark.

    You probably have to add back $100k for batteries, and maybe another $50k for solar panels. You are also looking at some base level of engineering to figure out the power needed to get up on the foils, and then a way to instal the engines so the props are wet while foiling. I am betting another $50k or so.

    All of this is obviously very rough numbers, and a lot of WAG's. But I am guessing the first one out of the molds would cost $1m or so invested, with a production cost of about $750k per boat.

    Again HC would be the ones to speak with though.
     

  14. Doug Lord
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    Doug Lord Flight Ready

    You'd have to experiment with the foils. The G4 foils are designed to lift about 80% of the boat on a single main foil and to work with leeway to do that. The guys at Holland could explain the pluses and minuses of using them on a power version of the boat.
     
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