Small gearbox

Discussion in 'Boat Design' started by Daan, Sep 7, 2020.

  1. Daan
    Joined: Sep 2020
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    Location: Netherlands

    Daan Junior Member

    Helle everyone,
    I am planning to build a small boat with an inboard engine. The engine comes from an old generator that I fixed a couple of days ago. The idea to build a boat is something I want to do for a long time now and now I have an engine I want to start building. The only problem I have right now is that I want some sort of gearbox to be able to put my boat at least in neutral or maybe even in reverse.
    Does anyone have a suggestion for a gearbox? I want to keep the project as cheap as possible so if anyone has a different solution to put my boat in neutral, feel free to share it!

    Thanks in advance!
     
  2. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    Welcome
    First warning
    Building your own boat is the expencive way to obtain a boat like object.
    Second warning
    Cobbling together a drive train is quadruply so

    What is the power rating of your engine?
     
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  3. Daan
    Joined: Sep 2020
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    Location: Netherlands

    Daan Junior Member

    The engine came out of a Honda EV3600 but I can't find anything about that generator but I can find information about the Honda EV4000 (Almost the same generator). It has a Honda G400 engine. It is a 10hp engine.
     
  4. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    We're out of my area of expertise.
    The smallest inboard engine I can think of is the Universal Atimic Four or it's diesel replacements. They're 20HP so their gear boxes would be robust enough for you. I don't know of any off the shelf 10HP inboards.

    Someone with greater experience on this matter should pop up within a few days.
    They will probably want to know the engine's operating RPM and work as well as the desired output shaft RPM

    Good luck
     
  5. Daan
    Joined: Sep 2020
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    Daan Junior Member

    Alright, thank you for the help!
     
  6. Squidly-Diddly
    Joined: Sep 2007
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    Squidly-Diddly Senior Member

    TBH, I'd search for that generator with blown engine and put your motor into it, then a couple of car or marine 12v batts and electric outboard. My theory would be the Honda electricals last forever, but some idiot will have done something to murder the engine, like never checking the oil, or filling with diesel, or filling oil with fuel, or starting then running on its side.

    Plus, you will then have a nice generator AND a versatile boat, vs a weird and limited boat. Use the generator to power the boat-build at remote location.
     
  7. Daan
    Joined: Sep 2020
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    Daan Junior Member

    That is a possibility but this way I have to buy an electric outboard engine and I don't want to do that. I already have an electric outboard engine and it is horrible how slow it is.
    (Fun fact. The only things that didn't work when I tried to fix the generator were the electricals)
     
  8. goodwilltoall
    Joined: Jul 2010
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    goodwilltoall Senior Member

    I think the smallest gear box twindisc makes is the tmc40, they are about $1000. Prob need to build an adapter plate for it as well. Maybe try finding a used one from a boat w bad engine.
    I have seen philipino tri's w inboard Honda engines, they are really neat. If I'm right they are direct drive to about a 9" prop, only problem is the engines are very loud, definitely need to get a muffler which from a past thread of mine someone mentioned the go carters as having good ones.
    Research how bankas are built , so many clever and inexpensive adaptions although, there are many components that still go into an inboard that could add up to a lot of money n time.
    Btw atomic 4 gearbox is inseparable from engine
     
  9. trip the light fandango
    Joined: Apr 2018
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    Location: Rhyll Phillip Island Victoria Australia

    trip the light fandango Senior Member

    A pressure washer has a 2to 1 gearbox that fits Honda's, but this can be done with belt or chain , then again it sounds like you're looking for an outboard leg It might be easier and lighter to use your electric outboard for reverse. A generator would be really handy. You can silence the motor by making a muffler that copies and minimises the sound waves at operating speed with a series of baffle plates that match. An sound insulated engine cover could tackle the general engine noise in a similar way. Water cooled is quieter normally.
     
  10. Squidly-Diddly
    Joined: Sep 2007
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    Squidly-Diddly Senior Member

    got any more on this, SOUNDS (pardon pun) very interesting.
     
  11. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The gearbox will be the cheapest part of the conversion. You can buy VolvoPenta, Westerbeke, etc. used transmissions for a couple of hundred Euros. However, converting the carburetor, ignition and charging system to be sparkproof will be an expensive and difficult project. Then you need to design and build an exhaust system that won't get hot enough to set the boat on fire. Finally, you need to design and build an air blower system to keep the engine cool enough. In short, there are plenty of small marine petrol and diesel engines for fairly cheap, which are a much better option. However, if you want a hobby and to design and fabricate all that, it great but you can't also have it for cheap.
     
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  12. trip the light fandango
    Joined: Apr 2018
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    Location: Rhyll Phillip Island Victoria Australia

    trip the light fandango Senior Member

    Sorry Squidly it was years ago that I looked into it , it is interesting ,first I suppose you find the length of the sound wave at operating revs then try different shapes to break it up, 1/2 length and repeat.......? Or buy 2 mufflers..ha.. Altlas Copco probably have a few clues.
     
  13. Daan
    Joined: Sep 2020
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    Daan Junior Member

    Thanks, I will look into that!
     
  14. Daan
    Joined: Sep 2020
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    Location: Netherlands

    Daan Junior Member

    I can isolate the exhaust, that will not be a problem.
    But what do you mean with converting the carburetor, ignition and charging system to be sparkproof?
     

  15. Daan
    Joined: Sep 2020
    Posts: 39
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    Location: Netherlands

    Daan Junior Member

    Thanks, this might be the sort of idea I was looking for.
     
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