Tiny power boat

Discussion in 'Boat Design' started by Rangerspeedboat, Apr 13, 2009.

  1. Rangerspeedboat
    Joined: Apr 2009
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    Location: Texas

    Rangerspeedboat Senior Member

    Hi all, I'm Ranger. You may also know me as rangersboat on this forum but I have seem to forgot the password and e-mail address that i used for the account. I'm 15 years old and have a 12' sears fibreglass boat with a 2.7 hp foriegn outboard. Its not that great for what I want.

    I'm thinking about building a little speed boat about 7 feet long with a custom drive system.

    Something along these lines http://www.vintageprojects.com/boats/little-boat.pdf

    I want this to be a cheap project. Around $175-200

    What I want to do is to have a 6.5 hp horizontal shaft engine powering a prop with an idler pulley clutch. Or direct chain drive.

    My dad is a carpenter and the plans for the boat in the link look simple, so that should be easy. The hard part for me is the proplusion.

    Another idea is to get an 4hp toro lawn mower engine and connect it to a lower unit from a mercury or johnson outboard. I have the toro engine so that sounds the simplest to me.

    I want this to be a light weight, little speed boat for going around the bay and bayous in my area.

    Does anyone have any suggestions or ideas?

    Thanks, Ranger
     
  2. rasorinc
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    rasorinc Senior Member

    Are you thinking of a hull something like this? If so go the the Glen-L site and in boat plans look at outboards. Lots of 7', 8', 9' 10' models
    https://www.boatdesigns.com/products.asp?dept=346
    If you are going out in a bay I suggest something at least 10'
     
  3. Rangerspeedboat
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    Rangerspeedboat Senior Member

    Something like that.........

    I would rather have in inboard, or and inboard motor mounted to a lower unit throught the bottom of the boat.

    I also have an 8 hp snapper motor, its slow but have plenty of torque.
     
  4. rasorinc
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    rasorinc Senior Member

    There is no problem converting a framed outboard boat to inboard. Just tried to offer you several hulls to look at. You want to have room for 2 people at least. The 1st boat I built was 14' and I started it as a junior in high school and finished it as a senior. If your interested it was the Flying Saucer by Glen-L and the year was 1958/59. You can get lots of help here in engine conversions just check out weed eater conversions.
     
  5. Rangerspeedboat
    Joined: Apr 2009
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    Rangerspeedboat Senior Member

    Well, I have decided on a boat. The boat that was in the link I provided earlier, which is http://www.vintageprojects.com/boats/little-boat.pdf or if you dont have the pdf download here is another link to a picture http://images.google.com/imgres?img...llow+boat&hl=en&rlz=1T4GFRC_enUS322US322&um=1

    I have printed out the plans and modified them so the boat is 8' long instead of 6' 6".

    I think I might use my 8hp (really a 10hp) snapper motor with a mercury 9.9 lower unit. This will give me some speed , but if that doesnt work out I can use the toro engine instead.

    I asked my wood shop teacher if I could build this boat and showed hime the plans and he said yes. So for the next 4 weeks of school I will be working on the boat as a school project.

    Work will begin tomorrow.
     
  6. rasorinc
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    rasorinc Senior Member

    Go For It And Do A Good Job. Remember To Post Pictures.
     
  7. Rangerspeedboat
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    Rangerspeedboat Senior Member

    I'll try to post pictures, but I will be in my woodshop class at highschool working on it. I dont know if he will let me take pics. I will try to keep everyone posted.

    I forgot to add that my snapper motor has electric start, this will make things a ton eaiser in the water.
     
  8. rasorinc
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    rasorinc Senior Member

    I'm sure your teacher will allow you to take pics of your build. Tell him you are on this forum and ask real nice. Again check out the weed eater engine conversions posted here. You will get some great ideas. Under power or propulsion. Yes electric start is a goodie.
     
  9. Rangerspeedboat
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    Rangerspeedboat Senior Member

    I did build a weedeater godevil, it worked but just that. The engine wasnt powerful enough for what I wanted but is great for shallow areas. I got rid of it.

    I saw the 5hp and 6.5hp custom go devils and that is where I got the link for universal joints and all sorts of other goodies.

    Thanks for the support.
     
  10. rasorinc
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    rasorinc Senior Member

    Your very welcome. Take your time and do a good job and ENJOY the build--that is what it is all about.
     
  11. Rangerspeedboat
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    Rangerspeedboat Senior Member

    Well, no work on the boat today. The teacher had to leave right as we got there, but we dropped the wood off there.

    I did get to work on the engine though, I got the pulley of the engine and tuned the carb for max RPMs. I dont know how long the engine will last in this configuration but my 5 hp briggs on my go cart survives to this day and it has no govenor.

    Is it better to sacrifice high RPMs on the engine for low torque RPMs? That is my question which I will ponder for days to come. Any thoughts?
     
  12. rasorinc
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    rasorinc Senior Member

    I prefer low torque rpm rather than high rpm which is only good for speed. I cannot help you with proping as I know little about that but there are others here who will assist you.
     
  13. Rangerspeedboat
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    Rangerspeedboat Senior Member

    Well I know which one I'm going for then. Speed :cool: I can however tune it to where I get a sweet spot at lower RPM for low speed torque.

    Can someone help me with finding the right prop?
     
  14. lewisboats
    Joined: Oct 2002
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    lewisboats Obsessed Member

    Pick yourself up "The Propeller Handbook" by Gerr...that will give you a running start

    Steve
     

  15. Rangerspeedboat
    Joined: Apr 2009
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    Location: Texas

    Rangerspeedboat Senior Member

    Engine setup

    Here are some pics of my engine that will be used in the boat


    [​IMG]
    Throttle linkage
    [​IMG]
    Carb
    [​IMG]
    Spring assist
    [​IMG]

    I made the throttle linkage my self using the govenor, govenor spring, and an old lawn mower throttle cable. My throttle lever is just the old one off the snapper. It may look all rigged up with the gas tank on the seat :rolleyes: But it works.

    Thanks, Ranger
     
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