Electric propulsion for small fantail launch

Discussion in 'Electric Propulsion' started by jconlin, Feb 13, 2021.

  1. jconlin
    Joined: Apr 2005
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    Location: MA

    jconlin Junior Member

    I am partner in a 17’ fantail launch that’s now powered by a 1908 Ferro one-lung engine.
    The existing engine is about 3 HP at maybe 400 RPM.
    WE’re thinking that an electric propulsion system might suit our usage better.
    How can we learn about the options of an electric-based system?
    Maybe something based on golf cart components.
    Jim
     
  2. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Hi Jim - I (and no doubt many others on here) am intrigued by your 1908 Ferro engine - can you tell us some more about it please, and perhaps include a photo or two of the engine and the boat?

    Was the boat also originally built in 1908 as well?

    I am no expert on electric propulsion systems, but if your heart is set on re-powering with electric, then your boat sounds like a good candidate for doing this with.
     
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  3. Will Gilmore
    Joined: Aug 2017
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    Will Gilmore Senior Member

    upload_2021-2-14_8-19-16.png
    Pictures would also be appreciated.
    -Will (Dragonfly)
     
  4. jconlin
    Joined: Apr 2005
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    jconlin Junior Member

    IMG_1766.JPG IMG_1709.JPG IMG_1766.JPG IMG_1709.JPG IMG_1327.JPG

    I don't know much about the engine. The other owner has had it for a long while. and we decided it needed a boat.
    The boat is based on a 1908 Palmer fantail launch in the collection of mystic Seaport Museum. They publish lines and offsets.
    Using the engine is a bit of an art and we think that we'd enjoy using the boat more if it were electric powered. Our usage is strictly for short, slow harbor cruises and it can be recharged from shore power between uses.

    Please suggest resources for simple shore-recharged electric propulsion.
     
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  5. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Jim, your boat is beautiful! Did you and your partner build her from plans supplied by Mystic Seaport?

    And that engine is a work of art as well - but no doubt it can be fairly cranky and tempermental unless you have a very good relationship with it, hence I can see why you would want to change to electric propulsion - a wee electric motor would be ideal for your intended usage.

    Please do try to find a good home for that Ferro engine - maybe a museum would like to have it?
    A pal of mine here would love to have an engine like that, but we are a bit too far away from you to easily come and have a look at it, and the Corona restrictions make everything even more difficult re travel.
     
  6. jconlin
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    jconlin Junior Member

    I can offer no more about the engine. It will likely return to its place of honor in the owner’s living room.
     
  7. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    Electric is simple. First thing you need is a bidirectional thrust block on the propeller shaft. That's because electric motors don't usually have them, and you need something to transmit the thrust to the hull. Then comes the actual motor with a matching controller and throttle. Next are the batteries, and charging. Options start with DIY with sh components from the local forklift shop, and end with custom installs. In between are individual part selection and purchasing, and generic prepackaged kits, either with or without battery. Gear reduction may or may not be needed, depending on the specific motor.
    Range depends on how much battery you can fit into the boat, space and weightwise.
    If you google 48V ev conversion, forklift motor car conversion, and similar, you will find a ton of info. To get you started here an example of a standard kit with PM motor: 5 KW Brushless Sailboat Kit https://www.thunderstruck-ev.com/sevcon-brushless-sailboat-kit-5kw.html
     
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  8. gonzo
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    gonzo Senior Member

    He only needs 2 KW to match the power of the original motor.
     
  9. Will Gilmore
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    Will Gilmore Senior Member

    It shouldn't be hard to convert a trolling motor for a few hundred dollars.
     
  10. gonzo
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    gonzo Senior Member

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  11. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    No need to convert anything, remove the rudder and install the trolling motor instead. Instant steerable pod propulsion. The problem is that cheap ones don't have the necessary power.
     
  12. jconlin
    Joined: Apr 2005
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    jconlin Junior Member

    I’d worry that trolling motors are designed to kick up on grounding and therefore the down tube can be flimsy/.

    I’d prefer to keep the existing running gear which includes rudder, prop, shaft, thrust bearing and some workable beds as foundation for motor and any reduction components. I’d think it more robust and reliable.
     
  13. gonzo
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    gonzo Senior Member

    Trolling motors are designed for the thrust they generate. They are not flimsy, but adequate for the forces. The whole complicated system you have now is not more reliable. For example, a leaking stuffing box in the shaft can sink the boat. Is your concern aesthetic?
     
  14. Artem Klochko
    Joined: Dec 2018
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    Location: Ukraine, Dnipro river

    Artem Klochko Junior Member

    Trolling motors are not designed for heavy duty. They are designed for low price, keep this in mind.
     

  15. gonzo
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    gonzo Senior Member

    That depends on what brand you buy. There are good quality trolling motors that give years of service.
     
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