Parallel hybrid variable pitch propeller question

Discussion in 'Hybrid' started by arn0, May 4, 2012.

  1. arn0
    Joined: Oct 2009
    Posts: 26
    Likes: 1, Points: 0, Legacy Rep: 24
    Location: DC

    arn0 Junior Member

    Hi,

    Simple question: how to match a single propeller with 2 different engines?

    My parallel hybrid boat (which runs either electric for low speed up to 9km/h either diesel for speed up to 12kw/h) shares the same propeller betweeen the 2 engines (volvo penta 2002 13kW and Perm PMG132 5kW).

    The propeller matches the Diesel torque and speed (reaches 3200 rpm), but it seems too big for the electric engine:

    While it should turn at 2000rpm under 48volt and 110A (approx 5kW) it develops only 2,8kW, reaching it's 110A limit at a lower rpm. The reason is that the controller limits the voltage so it reduces the rpm in order to cap the Amps under load.
    My conclusion: propeller is too big for the electric engine.

    I could try to change the reduction ratio between the 2 engines, but I am afraid it would bring overvoltage regeneration when the diesel runs and the electric motor acts as a generator (for example if I reduce the electric engine by 1:2 then in generation it will amplify the electric engine rpm by 2:1 and double the voltage), and those rpm would be out of the mechanical limits of the PERM engine.

    So do you think a variable pitch propeller would be the solution ?

    Thanks!
    Arnaud
     
  2. TeddyDiver
    Joined: Dec 2007
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    Yes.. a bit low power range you got but doable with either http://www.westmekan.com/propeller-equipment/
    or
    http://www.nogva.no/?CatID=1191
    BR Teddy
     
  3. arn0
    Joined: Oct 2009
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    Location: DC

    arn0 Junior Member

    Thank you Teddy,
    Would you know the approx overall cost of switching from a standard propeller to a Controlable Pitch one?
    Is it easy to install or are there many parts to be replaced?
    Since it is a quite simple 6,20m boat, I am looking to spend in the 1000 euro max, hope this is reasonable!
    Best,
    Arnaud
     
  4. TeddyDiver
    Joined: Dec 2007
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    The cost.. maybe around $3000 to $ 5000.. You better to get a quote from them. Westmekan has anyways gear down to 25mm/1" shaft dont remember Nogva but if they have they are half the price of WM. The setup consist of the cp propeller, shaft and pitch adjusting hydraulic pump system (manual or electric controls)
    Br Teddy

    Ps. Know they are a bit pricey bits of gear. A bit cheaper alternative is self adjusting propeller like Brunton's Autoprop but that's some $2500 maybe...
     
  5. TeddyDiver
    Joined: Dec 2007
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    Look also Gori-propeller. Its another self adjusting prop..
     
  6. arn0
    Joined: Oct 2009
    Posts: 26
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    Location: DC

    arn0 Junior Member

    Thanks Teddy,
    Sorry to catch up so long after your post.
    Self adjusting prop looks interesting, I didnt know them!
    I am wondering how it can actually deal with an electric engine, ie limit the pitch (=Torque = Amps) to higher the rpm (=Volts).
    I will ask the manufacturers.
    Best,
    Arnaud
     

  7. liki
    Joined: Nov 2008
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    Location: Finland

    liki Senior Member

    Teddy,

    any idea about the minimum diameter of the propellers they can supply? I reckon this kind of a boat would use 12" or 14" diameter.
     
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