Forums General Discussion Original Propeller size?

This topic contains 5 replies, has 4 voices, and was last updated by  Discoverie 1 year ago.

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  • #224001


    I’m in the middle of a repower to electric and I just found my first “goof” (of many, I’m sure). We based the gearing of the system on the original propeller specs of 20 x 13. However, I got mine back from the prop shop yesterday and it’s an 18 x 11. That’s a pretty significant difference.

    So two questions:
    1. What size do you all have (if yours is original)?
    2. If the original was, in fact, 20 x 13, do any of you have one you’d like to sell?

    Revery #219

  • #224003


    Our original was 20X13, same as listed in the 424 sales brochure. I always had the impression we were somewhat over-propped. WOT gave us somewhat less than the spec 3000 RPM, and a lot of black smoke. We changed to a 18X11 flex o fold, and it seems to be about right. Certainly not too weak. However, I was cautioned by flex o fold to not compare their prop to other props vis a vis the diameter and pitch. No usable correlation.

    Yes, I do have my original prop, but I am holding onto it in case I have a prop crisis in some remote location. Sorry can’t help there.

    Blue Moon

  • #224004


    Prop size selection is a function of the torque and speed of the engine that drives it and the gear reduction of the transmission and V-drive and of course the boat displacement and hull shape. Not all power plants work the same. I doubt that an electric motor would work well with the original prop. I suggest that you contact a propeller manufacturer and ask for their help.

  • #224006


    Thanks gents.
    Rich, roger on all of that and, if I were designing the powertrain, I’d definitely reach out to a prop manufacturer. But the reduction gearing was sized by the motor system manufacturer based on hanging a 20 x 13 behind it. And I trust their engineering skills.

    I may not have been clear in my original questions. The original size is actually a moot point but I asked anyway to ease my conscience…I didn’t make sure what I had attached (boat was in the water) before the system was designed. Mea culpa.

    So really, the only question I “really” have is “Does anyone have a 20x13LH for sale?”

    Revery #219

  • #224007


    I found the prop.
    This one available for trade or sale
    Shaft 1.5”
    Diameter 18”
    It marked with
    18LH11. I’m assuming that means a 18” diameter, left hand, 11 pitch

    1. 7D016338-9216-4E15-9605-3B32A3D5404C.jpeg

  • #224009


    Pic of 18LH11 mentioned above

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