Weed eater engine conversion

Discussion in 'DIY Marinizing' started by Ward, Jun 2, 2003.

  1. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    for a large slow boat you want a large slow reving prop..you are not going to get this with a weed wacker.....provided the prop is loading the motor so that at 6-7000 rpm its at full throttle then thats as much power as you are going to get into the prop ...the prop slip will be very high ..maybe 80 % from the figures I see
     
    Last edited: Oct 3, 2010
  2. rifraf
    Joined: May 2010
    Posts: 26
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    Location: AU

    rifraf Junior Member

    Hi again, been watchin but been too cold to go boatin, is nice and warm again and the 23cc redmax motors are goin strong, given up on the two motor idea for now, only cause i am lazy, lookin forward to taking the sevylor up the river again, is still fully inflated after sittin all winter under cover. for the people wondering if you can go upstream (not against rapids) with a weedeater, yes you can, will try get some better videos this year. the key with a small motor is gearing and clutch, for the watersnake and similar trolling propellors you want about 1200 - 1400 rpm to be successful, is good to see the success with a direct drive and small prop though, would like to get one of those props.
     
  3. goose_716
    Joined: Oct 2008
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    Location: Roy UT

    goose_716 Junior Member

    Prop Size

    I have a t-10 prop on boat with a 52cc motor has anyone tried the T-15 or T-18. it is a 7 inch prop not sure if that would be to big for the 52 cc motor. the t-10 is a 5 3/4 inch prop. From what i understand from talking to them it is not only bigger but a fatter prop also.
     
  4. Mark Wo
    Joined: Dec 2007
    Posts: 143
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    Location: Minnesota

    Mark Wo Senior Member

    Try it

    Please try the prop and let us know how it worked. The 52 cc motor had more than enough power to push the T-10 prop and I would think slightly bigger would be a good thing.

    Mark
     
  5. blad3
    Joined: Sep 2010
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    Location: Australia

    blad3 New Member

    I have a 29 cc engin and i am setting it up the same as Orphanedcowboy on page 9 what would be the best size prop?
     
  6. longtailboats
    Joined: Dec 2010
    Posts: 9
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    Location: thailand

    longtailboats Thai sean

    loooonnnngtailll

    Yup, used the 5.5 Honda nearly twenty years, the one with the galvanized water pipe and wood bushings on the shaft, bent it once going up a waterfall, straightened it and replaced the bushings, still have it, runs good. That engines never been rebuilt, all in ship shape. Now I mainly use the 13 hp. Honda setup. I rebuilt it after a ten year run, some time it was on the hovercraft, replaced only the rings, no boring necessary. I have the galvanized shaft for it but I use the newer aluminum hub with the shaft that runs on plastic bushings. I like it better; it is smooth and quieter than the galvanized unit. That throttle stinks; I use the throttle on the engine for the small skiff, on a good day I can make 20 knots. The cats speed is more like 15 but it cruises better, and it can power sail. The Thai setup is a beauty simple and elegant, a matched unit built from the engine down to the prop to perform best at a bit more than three quarter throttle, the engines power curve is efficiently matched to the props size and pitch. No modifications will improve performance, not needed. Also you can lift it alone and pop it on the boat. The power reduction is for moving heavy boats slowly or towing and is not to be confused with high rpm. speed gearing. An important factor is the shaft length, long not short like the western longtail, long means better power distribution resulting in the prop seeking its proper depth at every speed and surface propping at full throttle. The prop seeks its proper depth at all speeds this is a balanced setup with hands off control depth wise and a nudge with your leg will suffice, this is Thai Longtailing. Thai Sean http://longtailboats.webs.com
     
  7. longtailboats
    Joined: Dec 2010
    Posts: 9
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    Location: thailand

    longtailboats Thai sean

    Yup, used the 5.5 Honda nearly twenty years, the one with the galvanized water pipe and wood bushings on the shaft, bent it once going up a waterfall, straightened it and replaced the bushings, still have it, runs good. That engines never been rebuilt, all in ship shape. Now I mainly use the 13 hp. Honda setup. I rebuilt it after a ten year run, some time it was on the hovercraft, replaced only the rings, no boring necessary. I have the galvanized shaft for it but I use the newer aluminum hub with the shaft that runs on plastic bushings. I like it better; it is smooth and quieter than the galvanized unit. That throttle stinks; I use the throttle on the engine for the small skiff, on a good day I can make 20 knots. The cats speed is more like 15 but it cruises better, and it can power sail. The Thai setup is a beauty simple and elegant, a matched unit built from the engine down to the prop to perform best at a bit more than three quarter throttle, the engines power curve is efficiently matched to the props size and pitch. No modifications will improve performance, not needed. Also you can lift it alone and pop it on the boat. The power reduction is for moving heavy boats slowly or towing and is not to be confused with high rpm. speed gearing. An important factor is the shaft length, long not short like the western longtail, long means better power distribution resulting in the prop seeking its proper depth at every speed and surface propping at full throttle. The prop seeks its proper depth at all speeds this is a balanced setup with hands off control depth wise and a nudge with your leg will suffice, this is Thai Longtailing. Thai Sean http://longtailboats.webs.com
     
  8. rifraf
    Joined: May 2010
    Posts: 26
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    Location: AU

    rifraf Junior Member

    made a new frame today for motor, is more sturdy and still very light. video that shows most bits, http://www.youtube.com/watch?v=4ex292d52DA . everything fits together properly this time, prop height is easily adjustable and stays at the correct angle, any questions please ask.
     

    Attached Files:

  9. CaptBill
    Joined: Jan 2010
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    Location: Savannah,Ga

    CaptBill CaptBill

  10. rifraf
    Joined: May 2010
    Posts: 26
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    Location: AU

    rifraf Junior Member

    ok i am wondering, cause after the successful test ride 1km up river and back this arvo, that i may have over calculated the prop angle and in trying to get it closer to 90 degrees to the water am somehow losing some speed. from what i remember on the last frame the angle of the prop was slightly facing up, like 75 degrees to the surface, trying to push the back of the boat up a bit, and from what i can remember was faster, so will drill a new hole for the lower part of motor mount and test this in the next few days.

    but since i am not a 'real boat designer' can one of you more experienced ones please recommend a prop angle and even the depth into the water to propel a lightweight craft, in this case an inflatable, with 25cc motor with clutch and gearbox, currently am using a watersnake 2 blade 9 inch prop with not too much pitch and the prop speed varies from about 300rpm to 1000rpm, am even thing a three blade prop with bigger pitch might be possible
     
  11. CaptBill
    Joined: Jan 2010
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    Location: Savannah,Ga

    CaptBill CaptBill

    If you could figure a way to adjust the angle on the fly that would be ideal. Then you could adjust once you get up on a plane because the best angle will change then, slightly. Rig a cam lever to tweak the angle slightly then you could just throw it off or on. The old evinrude kicker motors were set angled like that. It works great for helping a small boat get on a plane. Figuring the best angle would be very hard to figure I would think. Best probably to just dial in what works for your boat.
     
  12. rifraf
    Joined: May 2010
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    Location: AU

    rifraf Junior Member

    being an inflatable with the setup on the back can change the pitch or angle to the water (sorry i am too used to roofs) to a varying amount. but even when trying to face the prop upwards a bit it appears to be too far from the back of the boat to have much effect, i guess will have to see what happens when the prop is moved closer to the boat again

    what was good this arvo though was being able to go upstream with a bunch of campers in awe of the inflatable watercraft, i apologised for the noise but kept it at low revs for the passing, the kids on their surfboards and toys were unable to keep up as i disappeared into the distance upstream

    these little weedeaters rock, and have 2 spare motors in case of mishaps, total of $40 spent at the recycling joint
     
  13. Paraprop
    Joined: Oct 2009
    Posts: 15
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    Location: Thailand

    Paraprop Junior Member

    Long tail kits available

    I have now prepared a kit for people who can fabricate the shaft themselves out of a 1 1/2" pipe and 3/4" steel bar. See picture. The weight of the parts shown on this picture including packaging is about 8 to 9 pound.
    As an option you can also have the engine base with transom mount and the chromed handle bar (39 1/2" long).
     

    Attached Files:

  14. hoytedow
    Joined: Sep 2009
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    Location: North of Cuba

    hoytedow Bananas

    That looks like a really good kit.
     

  15. Mark Wo
    Joined: Dec 2007
    Posts: 143
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    Location: Minnesota

    Mark Wo Senior Member

    Way cool

    How much including approximate shipping to the US? Are their instructions that go along with the kit? Is this for the Honday 6.5 hp motor or something smaller - I can't recall.

    Please let us know. I know many who would be interestedin this kit.

    Mark
     
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