What Size Prop for Mitchell 31 MK1

Discussion in 'Props' started by rich99uk, Aug 20, 2011.

  1. rich99uk
    Joined: Jan 2006
    Posts: 48
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    Location: portsmouth

    rich99uk Junior Member

    I have recently Purchased a mitchell 31 mk1 which i have been doing up.
    It didnt have a engine or any stern gear init when i got it, However thats all sorted now I Just need a prop but i have no idea what size to get?
    The Boat is a mitchell 31 mk1
    Engine is Ford Dover 2725E 130HP Fitted with heavy duty Fly wheel
    Prm402D Gearbox 2:1
    weighs About 4 Ton
    Is there anyone that has the same boat that can tell me what size prop they have got?
    Or has anyone got a cleaver way or working it out
    Many Thanks
  2. CDK
    Joined: Aug 2007
    Posts: 3,324
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    Location: Adriatic sea

    CDK retired engineer

    Google for propeller calculation, there is plenty on the web.
    You must know the engine rpm that belongs to the 130 hp maximum power, take 2/3 of that as cruising rpm and divide by 2 to get prop rpm. The outcome will probably be approx. 1000 rpm or a bit less. Then select the prop that gives you hull speed at that point, so you get good economy and have some reserve for bad weather.
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