Wave Powered Boat Design discussion

Discussion in 'Boat Design' started by kwhilborn, Apr 27, 2014.

  1. kwhilborn
    Joined: Apr 2014
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    kwhilborn Junior Member

    Hello.

    I'm new and wish to retire on the seas, so I am happy exploring up and coming concepts.

    Many of you have already discussed the Mermaid II 30" wave powered boat crossing the Pacific, but this subject deserves its own thread.

    I will link to a Youtube video here for anyone that has not heard of or understand the concept.

    https://www.youtube.com/watch?v=UWpxtfmpVD4

    I visualize a hull approaching 50' with a smaller mainmast as backup.

    I would think the ships balance might be better if centered in the hull, but this is where I am unsure.

    A) What types of hulls might be best suited for this type of design? i.e. Would it help if the hull were V shaped at the ends to encourage up and down movements? The fins apparently add stability but instability (to a point) might encourage momentum.

    B) What would be a good hull shape? A shallower flat bottom barge type hull might be easier to push, but also easier to tip.

    I'd be interested in thoughts from people who have design experience on this great subject.

    Note:
    Wave Powered Design is also shown here..
    http://pesn.com/2005/09/21/9600154_Kneider_Wave_Energy/

    Hopefully this will be a interesting topic. It may save some of you a few dollars in years to come if these concepts become mainstream.
     
  2. cristofa
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    cristofa Junior Member

    ... a good topic!

    Of course I am biased, but coping with roll on a monohull would increase complication in the paddle mechanism, so a catamaran would offer a more stable platform.
     
  3. kwhilborn
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    kwhilborn Junior Member

    Yes. Plus a lot of cats have V hulls. The Mermaid II has been designed as a Catamaran.

    [​IMG]

    I've also heard the notion, "A stable position for a Catamaran is upside down, but a stable position for a monohull is at the bottom of the sea.".

    Nevertheless I would prefer to have a monohull. I love Catamarans providing they have center passageways. I dislike the Wharram type designs with top entrances because of the Heat and A/C lost while traveling from cabin to cabin. I would like to sail (eep.. this is wave power thread) in very cold/warm environments (I'm Canadian, eh.).

    Note: If I were only sailing in sunny seas I love how Wharrams force people outside to go from room to room. Adds a unique flavor to journey.

    I'd like to note your comment,
    In large monuhulls such as tankers, roll might actually be a propelling force as driving fins could be mounted all along the sides. This would also help stabilize the roll and make it less than normal. In the Youtube video note the circular designs he made for electric power generation. No matter which way a wave hits it helps spin the generator. Nevertheless a Bilge Keel or the likes seem warranted. Good call.

    I would be interested in hearing any design ideas about wave power on ...

    a) Both Catamarans or Monohulls
    b) Type of materials (Steel, Fibreglass, wood, aluminum, etc.) Wave power would provide different stresses than sailing.
    C) Hull shapes. How would balance front to back affect propulsion. I think this is one of the harder questions without experimenting.
    D) Hogging

    I agree Catamarans would be more stable, but that seems to be a given no matter what the propulsion is.

    These boats can do 5+ knots in waves. If someone could just figure a way to amp up pitch (without fuel) in calmer waters this would be very viable. Even a motor causing pitch on purpose might be more efficient. It is an interesting design concept (see first post) but open to wide array of design problems (and solutions).

    Example: Could a hull with a wide beam in its center of flotation increase pitch. This is the driving force, but would also be countered by the "fins", so even a ship designed to pitch might not pitch as much as some.

    I think this is a bit odd topic for most here, but it has potential. One member suggested the Mermaid II voyage might have been floating in currents, but if you look at videos in OP you can see this works well (in waves).
     
  4. BertKu
    Joined: May 2009
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    BertKu Senior Member

    I think it is a great topic. Love to see some boatbuilders and NA's giving their opinion and suggestions. Having watched the video, monohull seems to work well. Would there be a method or improvement to make it faster than 5 knots?. Bert
     
  5. philSweet
    Joined: May 2008
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    philSweet Senior Member

    Start by actually calculating the wave energy that is present in the fluid. Then figure out what fraction you can extract. You need wind somewhere close by to produce the waves, so route planning takes on a different aspect than either sailing or powering. There are some good lecture videos from MIT on waves which include momentum and energy analysis, and our member Leo Lazauskas has just posted a link here to an online document which also treats the subject.

    http://www.boatdesign.net/forums/hydrodynamics-aerodynamics/wakes-50254-2.html#post686122
     

  6. kwhilborn
    Joined: Apr 2014
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    kwhilborn Junior Member

    @ BerKu,
    I think methods will be found to harness pitch for free. A poorly balanced Sail or Motor affects pitch as example. Would this be more efficient in calm waters?
    I imagine the stern would need to round out to transom to allow as much pitch as possible, adding again that the "flippers" help stabilize pitching so it is not insane.

    @ Philsweet,

    Observing video link in OP or conducting the experiments given in OP article link are a great way to understand this. Average wave energies are not an accurate way to measure speed potentials. There are so many variables including boat balance, weight, drag, wave timing, increased distance in waves, and many variables. I think this is best done by creating simulations using various hull types. I'm just guessing as to what it might look like. I think Catamarines seem like better option for this so far, but it's interesting.

    Math will be great for finding what angle will provide the most propulsion for a given weight craft going a set speed, but I can't think of it.
     
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