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Discussion in 'Boat Design' started by Guest625101138, Jul 14, 2008.

  1. Tiny Turnip
    Joined: Mar 2008
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    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    Fangle pictures

    some shots of Fangle from our recent trip to the Isle of Gigha, off the Kintyre peninsula in SW Scotland.

    the pictures show our island circumnavigation, some 15 miles completed in 4 hours; creel laying, mackerel trolling and general mucking about. There is a shot of my friend Paul, with his very game mother in law Sally, who is 75.

    Getting the hang of the adjustments on the seacycle units, which are a little bit subtle, and otherwise very pleased with the versatility and good manners of the boat. We took her out in a F6, and felt quite comfortable. The low windage of the boat pays dividends, and the sharp hulls really do slice through the seas.
    [​IMG][​IMG][​IMG]
     

    Attached Files:

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  2. Guest625101138

    Guest625101138 Previous Member

    TT
    Certainly looks like it serves its intended purpose extremely well. Lots of smiles.

    You have done well to get a reliable and safe package with a novel set up. It looks neat and purposeful.

    What sort of interest did the boat get from onlookers?

    Rick
     
  3. Tiny Turnip
    Joined: Mar 2008
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    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    Thanks Rick. It did generate a great deal of interest, especially from the islanders, including the chap who hires out the kayaks. The draft was the one drawback with Fangle - she draws around 24", with drive legs and rudders down, and as the bay is very shallow at low tide, and a kayak really scores there. The islanders were particularly interested, seeing the potential for fishing and creels. The yachties were full of 'smart' remarks, but I reckon they'd struggle to make 4 knots dead into the wind!
     
    Last edited: Aug 24, 2009
  4. MLampi
    Joined: Aug 2008
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    Location: Bellevue, WA

    MLampi Junior Member

    I was quite slow this year, with a time of 1:22:00 or so. The trip across the Sound was only around 5.5 mph, possibly due to the tidal current and/or weeds in the prop. The return trip was faster at 6.5 to 7 mph, which leads me to believe it was the current. The extra weight of the outriggers and slowing to a crawl to take photos contributed to the slow time.

    My fastest time for this race was around 1:14:00. I took pictures then, too, but only a couple hundred.

    Michael Lampi
     
  5. Guest625101138

    Guest625101138 Previous Member

    Mike
    I was very pleased with my folding prop. It did not have any difficulty shedding weed.

    I expect you could make quite a nice little folding prop with 4 or 6 blades using 1/8" x 1" stainless flat bar. You would not need to do any welding. Would need someone to mill the hub with 4 or 6 narrow slots. I have not seen a 3mm end mill but they must exist.

    Rick
     
  6. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    Rick, your folding prop may be just what is needed to vault prop HPBs forward. Something akin to what happened after the Hobie flipper drive, may break out if this catches on.

    Your folder looks to be simple and reliable in design from the pics. Combined with the flex shaft, you're bound increase your wins in obstacle type races like the Murray...

    Looking forward to reading about it.

    Porta

     
  7. Guest625101138

    Guest625101138 Previous Member

    I believe I have now got a durable and convenient set up:
    It is about as easy to carry as a racing kayak.
    Takes very little set up.
    Is a stable platform requiring negligible skill to operate effectively.
    Will operate in shallow water around obstacles without damage.
    Will sit flat on the beach.
    Less effort for long distance than any other HPB.
    Is hardly affected by weed.

    It is an absolute fun ride that I look forward to getting out on every weekend.

    However, Vic, I am under no illusion about it "vaulting" prop driven HPBs into mainstream. It is one of life's little experiences that others can wonder about but unlikely to ever try.

    Actually it was funny on Saturday because the dinghy sailors arrived about the same time I did and just stood around contemplating the wind. I was going up and down the lake and eventually one brave sailor rigged up and ventured out. He capsized maybe 6 times before he gave up. So while I had tough going upwind I still made good progress even into the strong headwind.

    Speaking of wind have a look at the storm front that just came through Melbourne! The hail looked like snow. Brisbane had its hottest August day yesterday - it was 35C, 3 degrees above the previous highest. You have to think there is more in this than normal variability.

    Rick
     

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  8. MLampi
    Joined: Aug 2008
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    Location: Bellevue, WA

    MLampi Junior Member

    I'd be very interested in trying to make one of these, Rick. There are a couple of small machine shops here that should be able to cut the slots. Do you have drawings or sketches?

    Michael Lampi
     
  9. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    Maybe the demographics of population will surprise us. I monitor a couple of recreational kayak sites, and have been surprised by number of Hobie flipper drive owners. The aging population has disposable income, time and quite a bit of leg muscle strength, still. They look to low impact exercise while enjoying water surroundings, fishing, and recording their experience hands free. They would probably like the rush of keeping up with paddling youngsters while using leg power without the need for extreme exertion. The recumbent position of prop HPBs is probably easier on the joints and more user friendly compared kayaks and land bike recumbents.

    If one of the big boys takes this on and steps up with mass marketing, everyone will discover what they have been missing.

    Guess I'm quite the optimist tonight, hoping to see what the next couple of years bring.

    Porta





     
  10. Guest625101138

    Guest625101138 Previous Member

    Mike
    I have looked at what can be achieved with 4 blades as I cannot see an easy way to make a hub for six blades.

    If you are happy with the following design point I will send you some blade details:
    Prop Diameter 200mm
    Hub diameter 40mm
    Shaft speed 600rpm (requires your small sprocket)
    Boat speed 6.5mph (2.9m/s)

    Preliminary design is 4-bladed prop using blades made from 1/8" by 1.25" stainless flatbar.

    This should get slightly better efficiency than your current prop but I will give you a figure after I have done it accurately.

    Rick
     
  11. MLampi
    Joined: Aug 2008
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    Location: Bellevue, WA

    MLampi Junior Member

    I'd prefer something more like 550 rpm for that speed so I would have a bit more head room with the smaller sprocket, but I guess I could get a still smaller sprocket if need be.

    Sure - let's do it!

    Michael Lampi
     
  12. Guest625101138

    Guest625101138 Previous Member

    Mike
    I have attached some images of what it should look like when completed. The blade pivot pins will interfere but this means they will lock each other in place apart from the last one.

    You can get 1/8"end mills so the hub can be made quite easily in a little mill.

    There is also a dxf file if you want to look at it in 3D. You can get a nice viewer called edrawings:
    http://www.edrawingsviewer.com/pages/samples/index.html
    The dxf is an AutoCad file.

    I will email the rest directly once I have done some sketches.

    This prop should get similar performance to your existing prop; around 76%. You will need some 1.25" x 1/8" stainless flatbar and a 100mm length of 40mm diameter machinable aluminium round bar. I would not use stainless for the hub until you have made one and tested it. If you really like it then try to get a stainless hub milled up.

    Rick
     

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  13. Frappacino
    Joined: Aug 2009
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    Location: aus

    Frappacino New Member

    Hi Rick,

    i live in melbourne aus too and am not a boat builder at all, but I am a newbie kayaker who has a 3.1 metre plastic kayak which i take fishing sometimes (i.e. http://www.southernadventures.com.au/Images/kayakVoyager FX.jpg)

    I was wondering, would it be viable to do a DIY pedal drive (that uses a prop) for this kayak _WITHOUT_ having to drill a well through the kayak. I have read this entire thread and done some search on this forum but I am still not quite sure.

    For example, the flex shaft setup you have - do you think it can be adapted to a kayak by mounting it to the side like you have ? or do you think outriggers are required for this setup ?

    From my POV, my priorities for such a pedal drive are:
    1. can operate in oceans/areas with some wave/swells
    2. not super expensive. would prefer something where i can scanvenge parts (some type of twisted chain setup ?).
    3. somewhat reliable/stable it wont break down every 5 minutes. but i dont mind adjustments/fixes between trips and also doing maintenance.
    4. I can "Deactivate" the drive so i can do beach landings etc (kinda like how you can pull up the prop to clean weed)

    things i do not really care about too much are:
    1. speed/efficiency - if i build it its really to give my arms are break and my leg a bit of a workout when i am on the yak.

    personally i am willing to put alot of elbow grease in into this. also not in a hurry so it will be a continuous side project of mine.

    Looking for ideas at this point - would love to heard your thoughts.

    I would buy a hobie, but the process of doing this DIY kinda attracts me and I dont really like buying into a monopoly. plus everyone has one fo those haha
     
  14. Guest625101138

    Guest625101138 Previous Member

    It would work OK. Would need a rudder for ease of control.

    The biggest expense is a gearbox. Something like the Mitrpak with 12mm shaft. Even the 9mm shaft would be OK with tall gearing.

    You need an old bike to cut out the bottom bracket and two lower legs of the frame. A little added complexity to set up an inboard bearing to support a gearbox shaft extension. On a narrow hull like mine this is not needed.


    The folding prop like I have recently made has little drag when submerged and just trailing. It is also beachable as it just folds up and the shaft flexes up.

    The hull limits performance but 6 to 7kph should be easy to sustain.

    You can get boxes for similar price in Melbourne and Brisbane but they do not have a stainless shaft. If the price of the box is a serious impediment then you need to start hunting around on Ebay. They come up now and then. You can also buy much cheaper open nylon drives that might be OK in your application given that the hull limits the performance efficiency of the drive will not matter. You will achieve close to limit with 60W. Going up to 200W might gain an extra 1kph.

    Rick W
     

  15. Frappacino
    Joined: Aug 2009
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    Location: aus

    Frappacino New Member

    >> You can get boxes for similar price in Melbourne and Brisbane but they do not have a stainless shaft. If the price of the box is a serious impediment then you need to start hunting around on Ebay. They come up now and then. You can also buy much cheaper open nylon drives that might be OK in your application given that the hull limits the performance efficiency of the drive will not matter.

    Thank for the thought Rick.

    I am willing to pend in the hundreds, over a long period of time, to play around with this, so I am not a pauper. But in this economic climate value is important for me.

    Whats a open nylon drive ? is this a cheaper version of the 90 degree mitrak gear box ? or are you refering to something else ? can you post a link to this nylon drive ? Much appreciated if you can point to some melb suppliers or something as I am not sure what keywords to search for.

    thanks in advance
     
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