LH to RH drive conversion

Discussion in 'Inboards' started by hyperdog, Jun 17, 2011.

  1. hyperdog
    Joined: Jun 2011
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    hyperdog Junior Member

    hi i opperate a twin prop 11 1/2 m passanger boat both engins opperate the drive to LH props could this be changed to a LH and RH prop system . i understand this would stop the boat crabbing
     
  2. gonzo
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    gonzo Senior Member

    What kind of drive or transmission do you have?
     
  3. CDK
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    CDK retired engineer

    You got that right hyperdog.
    All you need is a gearbox with the same fwd and reverse ratio, so you can put one in reverse while running forward. To achieve that, the bowden cable (or hydraulic cylinder if that is what you have) must be attached to the other side of the gear lever.

    With a bit of luck, your gearboxes qualify. If not, you need the replace one of them. It is a good habit to cool that one because it has to dissipate more heat.

    And you need a new prop for that side of course.
     
  4. hyperdog
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    hyperdog Junior Member

    the trans are 1/1 ratio model 10/18/002 velvet drives
     
  5. CDK
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    CDK retired engineer

    Beautiful, all you need to do is order a mirror image of the prop you have now.
    If your boat is equipped with Teleflex or similar controls, you can simply transfer the gearbox cable to the other side of the lever.
     
  6. hyperdog
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    hyperdog Junior Member

    ok CDK just one more i have been told that it is bad to run the gearbox in reverse as it will short the life of the box is that true or not ????????????
     
  7. hyperdog
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    hyperdog Junior Member

    ps thanks for the other answer cheers
     
  8. CDK
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    CDK retired engineer

    When gearbox makers point out which types have the same fwd/rev ratio so can be used in a ccw propulsion system it can't be that bad. There is an extra set of gears engaged, so there will be a bit more friction and wear.
    I assume the main cause of gearbox damage is switching at high rpm or with improperly adjusted cables.
     
  9. hyperdog
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    hyperdog Junior Member

    ok ????? but will it run at full power in reverse?????? cheers
     
  10. gonzo
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    gonzo Senior Member

    Velvet Drive transmissions should not be run backwards. It will destroy the transmission. You need a reverse turning engine and then the transmission will be fine.
     
  11. hyperdog
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    hyperdog Junior Member

    thats what i thought cheers gonzo
     
  12. CDK
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    CDK retired engineer

  13. hyperdog
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    hyperdog Junior Member

    ok so what your saying is that i can just change the cable on the morse control to select the reverse gear for forward propultion (ie with a RH prop) on my 1:1 ratio gear box and that will give me a LH prop and a RH prop with 2 engines that are both LH drive and it will run just the same on the RH box in reverse as it does on the LH box in forward ..... and wont DESTROY my transmission..................??????????????????? o and if the velvet drive wont run in full power in reverse can you sugest a box about the same size that will cheers
     
  14. Tahoerover
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    Tahoerover Junior Member

    You need a reverse rotation of one engine and adjust the oil pump in your velvet drive for the new direction. A V.D. uses a sun gear for reverse and it is not designed to consent use.
     

  15. CDK
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    CDK retired engineer

    Please read the Velvet manual or brochure, the links are in post #12.

    The manufacturer clearly states on page 1 than "both designs require a left hand engine and will turn a right or left propeller with equal efficiency".

    The owner's manual also addresses another myth on page 6 by stating that freewheeling during trolling or sailing does not harm the transmission.
     
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