A very small trolling boat

Discussion in 'Boat Design' started by Lurvio, Feb 18, 2010.

  1. portacruise
    Joined: Jun 2009
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    portacruise Senior Member

    Lurvio, I would love to hear more about how your ankle movement system works. Is this method already being used somewhere, or did you invent it yourself? Do you have sketches or pictures? Do you have to keep your ankle tilted while pedalling at the same time to make a turn? Is the rudder spring loaded to a straight line position, so that the ankle movement is only used for brief periods of time when making a turn?

    One paddle wheel in the rear should be easier to control that the two I had at the bow when I tried it. I did get some water splash and a little noise when in operation, compared to the completely silent no splash propeller system. The weight was greater with the paddlewheels than the prop system and required careful balance on my very short boat.

    Hope some of my experience helps with your project. Go for it and have fun as I did!

    Porta


     
  2. Lurvio
    Joined: Jul 2009
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    Location: Mid of Finland

    Lurvio Mad scientist

    Thank you guys.

    I did draw a tunnel hull last night, dimensioning it so the top of the tunnel touches water with about 150 kg load. It looked lika a sharp nosed box. :p I think I'll sketch something flat bottomed at some point, to see what it would look like.

    Rick W
    I think paddle wheel that size (in one piece) could be fitted, but would alter the stern quite a lot. So maybe the big prop will be better. What would the pitch be in a 200 mm prop, and around 300 rpm's? I'm thinking three plades, because I will most probably make it myself and thats easest for me to divide in the lathe. 3 mm 6061 alu should be strong enough.

    Portacruise
    Here's a crude sketch of the system. The cables make a loop at the bow to clear the other pedal. I think bicycle brake cables are plenty strong for this kind of use, dont weight much and works well enough. I'm not sure of the rudder centering, but it can be easily fitted later.

    There's -25 degrees(celsius) outside this morning, so I wont be starting any boats in a while yet. But at the moment it looks like I'll stick with the original plan, except the bigger prop. The build wont cost too much and if doesn't work I have a nice decoration for my woodworking shop. :p

    Lurvio
     
  3. Guest625101138

    Guest625101138 Previous Member

    You need to spin it at about 600rpm. So gearing as you originally suggested of 1:10. You could expect a speed of 6 to 7kph. Suggested pitch is 230mm. The blades need to have 35 to 40mm chord.

    Rick W
     
  4. Lurvio
    Joined: Jul 2009
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    Lurvio Mad scientist

    OK, thank you Rick.

    The blade will look pretty much what I had imagined. Just to learn something, does increasing the chord have any benefits.

    Thanks to all whom commented so far. It is much appreciated. :)

    Lurvio
     
  5. Guest625101138

    Guest625101138 Previous Member

    The chord selection is a balance. Going larger than 40mm will reduce efficiency for this slow speed application. You could go smaller but then there is the possibility of bending the blades and the blades shape becomes a little more important.

    Rick W
     
  6. creekhound
    Joined: Nov 2009
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    creekhound Help me !!!!

    Omething to think of the lower you sit in the water the less vision you have of were you are casting!Unless you troll only?
     
  7. Lurvio
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    Lurvio Mad scientist

    Creekhound
    I think it'll mainly be trolling, but I see no big problem casting to 15-20 meters. In a sitting position I don't have as much force to swing the rod anyway. :)

    Just in case someone has not noticed, here's the thread of the ongoing building process on this little tub of mine.

    Lurvio
     
  8. creekhound
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    Location: aurora,Indiana

    creekhound Help me !!!!

    What was meant by my post is with a low seated position you dont know if you are casting in 6 inchs of water or 6 feet you also loose your ability to sight fish.Although i dont think you need to sit as high look at how high the fishing seats are on a bass boat 5 to 6 feet off water this is for the best view of your surrondings.Sitting to low to water is a common problem in kayak fishing i have seen people waste alot of time casting 20 or 30 feet fishing and not catching anything.This was becuase they could not see how shollow it was.
     

  9. Lurvio
    Joined: Jul 2009
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    Location: Mid of Finland

    Lurvio Mad scientist

    OK, a bit of a misunderstanding. :) On my homelake there's a bigger problem for sighting fish, the water is pretty brown around here. There's a lot of peat production upstream on the water system. One neighbouring lake has clear water (it only has small ditches to provide water in it) and I plan on going there at some point, but mainly I'll troll on my home lake. This is quite a small lake and I've lived here all my life so I have a pretty good idea of the shape of the lakebed.
     
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