Does a trolling prop have same rpm forward as reverse?

Discussion in 'Electric Propulsion' started by TonkaNL, Aug 23, 2019.

  1. TonkaNL
    Joined: Aug 2019
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    Location: Netherlands

    TonkaNL New Member

    Hi Guys! I’m new here on this forum.

    My handle is Tonka, and I’m from the Netherlands. I just bought a small polyester sloop/boat (4.9m, 250kg) and I am looking for an electric outboard (Haswing Protruar 5.0) As we all know, most (if not all) trollers are set up for a max speed of 5 mph. However, it seems that a prop of a different model Haswing (3.0G) has a simliar diameter, but higher pitched prop. This is because the latter has a gear driven propshaft, with a lower revving, but higher pitched prop. I think I can make this higher pitched prop fit the 5.0 outboard. However, because of the gear driven shaft of the 3.0, the 5.0 has to turn backwards..

    He 5.0 is rated at amax power of ca 2.5 kw, which is more than plenty for my application.
    Now my question is, do all trollers rev with the same rpm forward as they do backward? I think they do, but I don’t know and I can’t count that fast myself

    Thanks!

    Tonka
     
  2. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Best call the manufacturer to be certain. It would sure get complex if they don't, though.
     
  3. DCockey
    Joined: Oct 2009
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    DCockey Senior Member

    Some outboards recommend not using "reverse" continuously due to the design of the bearings and/or gears.
     
  4. W9GFO
    Joined: Dec 2014
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    W9GFO Senior Member

    In his case, running backwards would put the thrust load in the normal direction so the bearings should not mind, there are no gears.

    I see it is a brushless motor, it is possible that the reverse speed is programmed to be lower than the forward speed, if so it could be re-wired but I would question if it would really be worth the trouble.

    Lastly, are you sure the other prop is higher pitched? It does say it revs slower but it also says it is for smaller boats.
     
  5. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    What am I missing here ? If the prop goes backwards, so will the boat, unless you change to a prop with the opposite handedness.
     
  6. W9GFO
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    W9GFO Senior Member

    Original prop is left handed, the replacement he wants to try is right handed.
     
  7. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Thanks, I missed that detail !
     
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  8. kerosene
    Joined: Jul 2006
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    kerosene Senior Member

    You need to check with electrics people. I know little but I have understood that the motors can have asymmetries in the designs. Think for example that the coil "fires" 1deg before or after the dead center magnet passing. And that these setups can cause compromises to the secondary direction.
     

  9. W9GFO
    Joined: Dec 2014
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    W9GFO Senior Member

    All the brushless motors I have dealt with have been symmetrical in that regard. Swap any two wires and they run the opposite direction. However, my experience is limited to sensor-less motors, maybe those with sensors could have a timing offset. I wouldn't expect that but I don't know.

    Cheap DC trolling motors are symmetrical, you remove the housing, rotate 180 degrees and reinstall to change direction of rotation.
     
    kerosene likes this.
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