Feedback for the Trout boat

Discussion in 'Boat Design' started by kowabanga, Aug 31, 2016.

  1. kowabanga
    Joined: Aug 2016
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    kowabanga Junior Member

    I was helping with a video for a boat with a leg powered fishtail like drive and when I googled that this forum came up first :)
    So I hope I might get some constructive criticism for the video and answer as many questions as possible so I am ready to answer them again in the future.
    We didn't have a good camera or a cameraman and the weather has been very annoying lately for us so this is the best footage we could get. If there will be any interest in the boat we will record many more and soon.
     
  2. Wohe
    Joined: Mar 2009
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    Wohe Naval Architect

    Do you have any data about efficiency of such proplusion system?
     
  3. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    No matter who good the paddle is, if it is going to wag the boat back and forth its going to loose efficency.

    Have you compared this to the Hobie Mirage drive?

    Is that a fixed fin? The Hobie flexes to become a more efficient fin.
     
  4. kowabanga
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    kowabanga Junior Member

    I honestly don't know how to do that so if you could tell me what information is needed to calculate it I will do my best :)
     
  5. kowabanga
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    kowabanga Junior Member

    I will upload another video tomorrow where the waging is minimal. This was caused by a part breaking in the pedal part of the drive. Over time the amount of changes done to the body and the drive made some parts simply break during tests. It is all made out of multiple parts in order to change it depending on what needs to be changed. In the next version the whole drive will be one part and that will eliminate the problem. Also yes the waging reduced the speed in this test which before, was 12 km/h that you will see in the next video. The speed is also reduced overall because of the weight of the boat in its current state.

    The fin isn't fixed per say, there is a strong rubber which you can see at the end of the tail here https://gyazo.com/0661564dce694387fd3f600741d2b8e7 it allows for the fin to rotate accordingly to how much you pedal.

    EDIT: actually here you go, in the clip you can see that the waging also reduces when you're going faster. https://youtu.be/doYQDRwf6IQ
     
  6. Petros
    Joined: Oct 2007
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    Petros Senior Member

    There is a fairly easy way to determine efficiency of human powered craft.

    You outfit several of the same hulls with oars, perhaps a kayak paddle, and your standard drive set up. These are your test vehicles. You can use the same hull of course, but that means changing the drive configuration between each test.

    You should use several different people, large and small, fit and not so fit. Than outfit each person that tries each drive system with a heart monitor (the inexpensive wrist type will work fine), and some way to measure speed, a GPS perhaps, or some simple speedometer. give them a note pad to write down their results. Best to do this on a windless day, or take a run in each direction and average the results.

    The same operator in the different configurations, at the same speed should have the same heart rate if all are equal. But one of the drive systems will have consistent lower heart rate. Therefore, the lower the heart rate for going the same speed, is the most efficient drive.

    there are other means too, measure oxygen up take, but that takes more costly equipment. You can even monitor heart rate with a stop watch, but it would be more accurate to just have a wrist mounted heart monitor.

    There is no estimation required, no fancy calculations: the lower the heart rate, at the same speed, the less effort it takes to drive the boat forward. And the results are not theoretical, but actually measured directly in real conditions.
     
  7. kowabanga
    Joined: Aug 2016
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    kowabanga Junior Member

    In that case we will do it next time we go out testing. Even though testing it might be a pain because it will have different hulls and the length of the tail will be much different for them.
    Also, when you say paddling you mean one or two paddles? Because all I remember from using one paddle is it being a pain in the *** to move when the drive broke in one of the older tests.

    This one isn't really focused on speed and efficiency that much either. It's more of a recreational type and one, we plan in the near future is focused on speed.
     
  8. Manfred.pech
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    Manfred.pech Senior Member

  9. kowabanga
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    kowabanga Junior Member

    We have actually seen those before and ours is a far way from any of those blueprints. The only similar thing might be the fin and even in that they are missing 2 things we have on our endings. They don't seem user friendly either. We have tested many that have looked like these before and there was just no point. Slow and unable to support our size of the boat which is going to be even bigger. 2 times the boat barely moved because the turning of the fin didn't have enough tension on it.
     

  10. Petros
    Joined: Oct 2007
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    Petros Senior Member

    the test is meaningless unless you use identical hulls, or use the same hull. if it is a different design hull it will have different drag, different weight, etc.

    You can not really paddle a wide hull well at all with a single paddle. I suggest making a really long kayak type double ended paddle. That works remarkably well, even on wide hulls. Also try fitting some oarlocks and use long oars as another test. both of these will give you conventional baseline human powered boating with which to compare it.
     
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