Converting an Outboard to Diesel.

Discussion in 'Outboards' started by rustybarge, Aug 26, 2014.

  1. rustybarge
    Joined: Oct 2013
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    Location: Ireland

    rustybarge Cheetah 25' Powercat.

    Thanks West, the European market is very depressed at the moment, Germany France and Italy are all in negative growth; not much hope of a sale!

    I've just bought a Chinese monkey bike, and I'm very pleased with it so far.
    Fits nicely on the back of my Cat, weighs just 75kg which means you can 'walk' each end onto the transom quite easily.

    [​IMG]

    So far after 1000 km:
    max speed about 55mph,
    100mpg
    Twitchy handling, you really have to drive the beast around corners to get the rear tire to stick, otherwise the bike weaves on the bumps.
    Nicely engineered, no plastic ABS mouldings, torquey 125cc engine pulls well from standstill in 2nd gear.
    Keeps up with traffic no problem

    Fingers crossed, no issues so far; only cost £1000 new with 2 year g'tee.
     
  2. whitepointer23

    whitepointer23 Previous Member

    This one has been around for a few years but still no actual outboard has been made. I think they are copying the old commer knocker truck engine from the 60's. They were a great motor but noisy. If this outboard ever gets produced it would be a fantastic engine .
     
  3. rustybarge
    Joined: Oct 2013
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    Location: Ireland

    rustybarge Cheetah 25' Powercat.

    They seem to got a massive grant from the government.
    Complicated complicated engineering....

    There are two more competitors in the market.

    http://www.ecomotors.com/
    http://www.achatespower.com/
     
  4. whitepointer23

    whitepointer23 Previous Member

    Some sort of small turbine running on diesel would be interesting. If you could fit a big enough reduction on top of an outboard leg.
     
  5. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    There is no 90 degree change in that box, thats parallel output front engine/wheel drive box as far as I can see in the cutaway
     
  6. powerabout
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    powerabout Senior Member

    Merc built a turbine outboard to test when the US military said we will no longer have gas/petrol.
    the BRP e-tec will burn Jet a1 so that won out.

    I like the photo, 300hp diesel on a lower unit from a 100hp 2 stroke, that will work NOT
     
  7. AndySGray
    Joined: Jun 2014
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    Location: Cayman

    AndySGray Senior Member

    diesel 'semi-outboard'

    What if, instead of mounting the diesel directly on the lower unit, we used a hydraulic motor.

    The diesel then becomes a remote power pack on deck, and a couple of beefy hoses run to the outboard.

    I was thinking it would require a step up g/box as the Hydraulic motors are generally slower reving...

    but then the final bevel drive and transmission slows it back down again...

    so... why not lose the lower leg and just fit the prop directly to the Hydraulic Motor - a sort of Micro Azi-pod if you will - slow running with a big prop.

    I realise that is getting a bit farther away from converting an outboard to diesel but it might inspire others.


    I had a further thought when I spotted how cheap some of the smaller hydraulic pumps are - what about the mythical Hydra - Multiple heads on a single body...

    The power pack could have either a single large pump or dual smaller redundant pumps and then you have a twin diesel 'semi-outboard'

    :idea:
     
  8. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    Buy the time you make the hydraulic motor water proof/rust proof and add thrust bearings you may as well use a bevel gear and put the motor on top.
    You still need a housing to rotate to steer as well.
    Now if someone had a hydraulic motor with these features built in then we would have a winner

    and then its only going to work at displacement speeds
     
  9. rustybarge
    Joined: Oct 2013
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    Location: Ireland

    rustybarge Cheetah 25' Powercat.

    You're quite right, I must have clicked on the wrong photo...!

    It seems that the older 4 wheel drive synchro gearbox takes it's drive through the front diff, so maybe it's only a 'power to the back wheels' when the front wheels are slipping arrangement; but it would be very easy to lock the diff with a small weld On the planetary gears.
     
  10. rustybarge
    Joined: Oct 2013
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    Location: Ireland

    rustybarge Cheetah 25' Powercat.

    It's hard to get hold of jet 1a at the marina!!!
    I actually got a quote on one of those, ordinary 50 hp was about £5k, the dual petrol/ fuel jet1a/paraffin heating oil version was £12k.....:eek:

    As far as I could see it was just a switch that remapped the ecu ignition.( I think it has a fuel pre-heat for the kerosene)
     
  11. rustybarge
    Joined: Oct 2013
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    Location: Ireland

    rustybarge Cheetah 25' Powercat.

    Another problem with hydaulic drive is the 20% inefficiency, that's a lot of power to lose.....
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    Which would go a long way to explaining the absence of them.
     
  13. rustybarge
    Joined: Oct 2013
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    Location: Ireland

    rustybarge Cheetah 25' Powercat.

    .....and hydraulic motors make a really irritating high pitch noise all the time, just like on those excavators.


    The idea of a transverse engine/gearbox/ bevel 90/ outboard leg bottom gearbox has an extra bit of loss in the system over a standard car, but exactly the same as a four wheel drive 'front transverse engine' vehicle..anyone know the losses in the drive system for a car with bevel drive to rear diff..?
     
  14. rustybarge
    Joined: Oct 2013
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    Location: Ireland

    rustybarge Cheetah 25' Powercat.

    Can anyone come up with a smaller Diesel engine/ gearbox arrangement that has a bevel output gear that could rotated?

    Lighter than the VW engine, we only need 70hp at the most.....

    Something that works 'out of the box' as it were......
     

  15. rustybarge
    Joined: Oct 2013
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    Location: Ireland

    rustybarge Cheetah 25' Powercat.

    Update on the VW drive system.

    Sounds perfect:

    "The PTO and prop shaft are always driven, and a clutch pack on the rear differential input determines how much power the rear axle receives. Like this:"

    [​IMG]

    So the power is permanently connected through the four wheel drive bevel gearbox , on the car there is a slipping clutch on the back axle to regulate the amount of drive to the rear diff......
     
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