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  1. #1
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    Prop diameter vs rpms?

    Gidday guys

    I've always been of the understanding that 1" of pitch up or down is worth
    approximately 200rpms up or down (as a rule of thumb)
    What is the rule of thumb for the effect of changing diameter on rpms?. I have
    heard that 1" of diameter is worth approximately 500 rpms?
    Anybody with a lot more knowledge than me able to advise?

    Looking at replacing my old 4 blade OMC Shooter (13 1/2" x 21 1/2", started life as a 23")
    with a SOLAS 14 X 20 HR4

    Thanks and regards to all
    Last edited by wettek; 06-04-2020 at 08:39 PM.

  2. #2
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    I'd like to hear on this to. Also the solas runs very very stiff , 20 prob more like 22 23. What people r sayin that run them , at least the bigger props in 24 28 range

  3. #3
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    Lake Havasu City AZ
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    On my deck boat with a 428 hp V8 Erude, I spin a Merc Revolution 4 blade 14 5/8 X 19 6200rpm and I spin a Suzuki 16 X 20 three blade 6200rpm. My motor makes peak HP at 6250 If this helps.

  4. #4
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    The solas scorpion model run 2'' stiff, cant comment on the other models. ive found diameter doesnt change rpm much but bigger always seemed to perform better than smaller. they market the scorp for bass boats, my 24 has super lift all around and 15.25 diameter. solas makes an L-4 MODEL i would like to try. every rig is different.
    Last edited by KIRCHNER; 07-04-2020 at 12:09 PM.

  5. #5
    Join Date
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    slough, england, united kingdom
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    the solas 14 x 20 HR4 will drop you down around 800 to 900 rpm ... your going up in diameter and will lose 200 + rpm = from that alone,
    your pitch is going right up to about 24 (ish) , plus the style of the solas is much more blade area and with an extra blade its also a lot heavier...

    Just my opinion.

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