Surface Drive Info

Discussion in 'Powerboats' started by jprev, Oct 2, 2003.

  1. jprev
    Joined: May 2003
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    Location: Florida

    jprev Junior Member

    I have done some searches online but have come up with nothing. Anyone have any suggestions? I could use some technical drawings, principles etc. The big commercial drives are out of the question.

    Thanks,

    Joe

    :confused:
     
  2. Willallison
    Joined: Oct 2001
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    Willallison Senior Member

  3. Guest

    Guest Guest

  4. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    What is the intended application and HP?
     
  5. jprev
    Joined: May 2003
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    jprev Junior Member

    Are you sitting down?

    The intended application is a real world pupulsion system for a 15-17 ply, multichined skiff. Gross weight 1000 lbs max, beam, oh say 6'. Power plant issssssss a lawnmower engine. Horizontal shaft. 27 HP/3500 RPM. Easily adaped. Air cooled. HP may be a problem, I might have to go with twins. :) Or da farfegnugen. (VW) But damn I am having a hard time finding them.

    Thats it. I am not crazy. I have the basic design in cad using aluminum heavy wall tubing, u-joints, pillow blocks and thrust bearings. It still has issues but I think it just might work. The whole thing looks sort of like a upside down skewed radio tower from HBO's new series Carinval.

    Thanks,

    Joe
     
  6. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    I think it's OK. However, you'll have to find a propeller designer and someone to manufacture it. It should run $3-4K for one done at a reputable propeller machine shop. Also, lawnmower engines produce very little HP for their weight. They are designed to run at a constant RPM and have little torque at low RPM. It may be possible to do major modifications and make it work, but it will end up costing more than an engine made for the application. Multichined skiffs are for sailing/rowing. The idea is to have a narrow waterline with reserve floatation up. It is the opposite of what you need for a planing hull with very low HP as you are talking about. Maybe a flat bottom boat may get up on plane with 27HP.
     
  7. Guest

    Guest Guest

    Adaptation of land engines

    There are a number of adaptations required for non-marine gasoline (petrol) engines to render them safe for marine use. Contact the local Caost Guard boating safety office.
     
  8. jprev
    Joined: May 2003
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    Location: Florida

    jprev Junior Member

    Ouch!

    Three grand for a prop?! That's a issue I can't over come. If I can't find a reasonalbly suitable stock prop then it can't be done. (I understand the difficulty here. Normal props are not designed to work as surface drive props.)

    Regarding the mulitchine... It is basically a flat bottom boat with a slight V aft but with most of it's V forward to reduce pounding. The flatness of the bottom aft also makes for a simpler to build, easier to work from craft. Plus, the only place in Fl that you can use a flat bottom boat is inland on a farm pond. Otherwise your fillings get shaken out.

    Thanks for the word about conversions of engines to marine applications. I will be sure to contact their web site for that info. If you have a URL I would appreciate it.

    Regards,

    Joe
     
  9. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    I am working on a design for surface drives. A 36" prop is $22,000.00 . The problem with your application, is that it's not standard. However, with surface props, to make them efficient have to be matched to the boat and installation.
     
  10. MARTIN S.
    Joined: Mar 2004
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    Location: ARANSAS PASS, TEXAS

    MARTIN S. New Member

    Surface Drive Outboard

    JOE,
    I HAVE BEEN READING SOME OF YOUR MESSAGES. I CAN TELL YOU THAT
    I HAVE KNOWLEDGE OF YOUR VERY SUBJECT ABOUT POWERING THE SKIFF
    WITH THE AIR COOLED ENGINE WITH A SURFACE DRIVE. I HAVE BEEN DEVELOPING A SURFACE DRIVE OUTBOARD WITH AN AIR COOLED ENGINE
    AND IT DOES WORK. I CURRENTLY HAVE A 10 H.P. PROTOTYPE THAT I
    HAVE BEEN TESTING FOR OVER A YEAR. THE 27 H.P. KAWASAKI I PRESUME
    IS AN EXCELLENT ENGINE. I WOULD SAY IT WOULD POWER YOUR 1000lb
    FLATBOTTOM SKIFF FINE. YOU WONT TAKE IT TO THE RACES BUT IF
    YOU ARE LOOKING FOR SHALLOW WATER RUNNING IT WILL WORK. I CANT
    FIGURE OUT THIS FORUM TO WELL BUT IF YOU GET THIS SEND ME
    AN EMAIL DIRECT dragons002@yahoo.com
     
  11. xrudi
    Joined: Jul 2003
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    Location: Germany

    xrudi Senior Member

    Levi Drives

    We have developed a suface drive for fisherman with hand steering. The smaller version Levi Drive 170 - 125 would be suitable for your application.
    Visist our webpage www.levidrives.com.
    We have a set of props for these drives 17" and 5 different pitches CW,CCW. The price is about 250 $ US.

    Cheers Capt Rudi
     
  12. Hydro
    Joined: Nov 2004
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    Location: New Zealand

    Hydro Junior Member

    prop price

    Hey Gonso
    Where do you buy your props from ? that seems very expensive.
    Is that in US $ , we would sell that size for a lot less.
    Greg
     

  13. Agrodyne labs
    Joined: Nov 2014
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    Location: Nanaimo BC

    Agrodyne labs Junior Member

    Totally doable....

    I got a small racing boat using a home-made surface drive. Works awesome. Could slap it into your skiff easy.

    Lawnmower engine power to weight? Suzuki DT-8 2 stroke 8 HP O/B weighs 73.5 LBS, Honda GX-240 weighs 54 LBS,makes 7.9 HP. Granted, my DT-8 powerband is more suited to turning most of the props I have tried, but I'm getting really close....

    Now, My current race boat uses a Honda GX-270 , 8.5 HP , weight is less than 50 LBS owing to the use of performance parts readily available for these "lawnmower" engines. I can achieve 7000 RPM+ on pump gas, and 25 HP easy if I want to.

    Just build one. It's a hoot.
     
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