The Controllable Pitch Propeller, a summary.

Discussion in 'Props' started by apex1, Dec 26, 2009.

  1. gunship
    Joined: Jun 2009
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    Location: Sweden

    gunship Senior Member

    for outboards there are semi controllable. that is, loose some bolt and pull the plades in another preset position. we use one on our plastic tub at our summer place. when going for a cruise, its one mode, when skiing or tubing its another position. also great for when you acidentally run in to a shoal or something else for some reason and you only loose a couple of blades.
     
  2. thudpucker
    Joined: Jul 2007
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    Location: Al.

    thudpucker Senior Member

    For small boats, I used one in the 50's that worked very well and it must have been cheap to make and own.

    I scribbled one together for this board last year when the French guy led us in Circles over that. Apex just brutalized the poor guy, but he asked for it.

    My 'invention' could be made in a barn. But my CPP would be for small HP only. Nothing over 10 Hp.

    My CPP would be drubbed out of the world by a small outboard.
     
  3. brian eiland
    Joined: Jun 2002
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    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

    Kasten is from Scandnavia for about half of the year. His wife is Swedish
    http://www.kastenmarine.com/team.htm

    Prop discussion here:
    http://www.kastenmarine.com/CPprops.htm


    _____________________________________________________________
    Thanks for bringing this subject up Apex. I'm very interested in the use of a CPP prop arrangement on the single-engined kite/trawler I posted here:
    http://www.boatdesign.net/forums/boat-design/new-age-trawler-motorsailer-kite-assisted-poweryacht-20319.html

    The power would be a single main engine sized to develop the vessel’s desired top speed....
    Supplementing this single main engine would be a single DC diesel/electric power unit to provide for....

    The entire ship would be powered by only two engines, basically sized to provide:
    1) Full main diesel power, unimpeded by interceding diesel/electric conversion
    2) Slow speed operation and ship’s systems via the smaller diesel/electric unit
    3) ‘Twin power’ emergency backup as either engine can run all gear
     
  4. Fanie
    Joined: Oct 2007
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    Location: Colonial "South Africa"

    Fanie Fanie

    I hope so.

    Prop of the future. There's an app for them that may come up in the near future (year or two), and it's going to be big. Small props to big ones.
     
  5. dskira

    dskira Previous Member

    I don't see anything close to Scandinavia in his web-site. We all come from somewhere with a wife from somewhere.
    Why you mention that? for his knoweldge of the CPP?. And his wife is profecient in CPP since she is Swedish?
    He is a member like me of the SNAME and SBYD.
    He spend time in Malaysia, and in the southwest. And also in his office in the US
    He is the only US naval architect as far as I know who try to explain and impliment the CPP. You like it or not.
    Could you tell me an other US naval architect who did the same job for the CPP, with a American wife to be sure he is in America?
    Cheers
    Daniel
     
  6. apex1

    apex1 Guest

    Your boat, and the way you use it makes a perfect example for a CPP installation! The wide variety of power demand (from trolling at 1kn to full ahead the next moment) makes it so extreme sensible.

    Yes you are in the ballpark! Maybe another 1 or 2000$ for the tube and bearings. (the shaft is ALWAYS housed in a tube)

    A standard Hundested or Helseth setup is in that range! A bit depends on the prop material of course, but that is the same difference with a fixed prop.

    let me have exact data (power / Nm) and I´ll get us some quotations as a example for this special case!

    Regards
    Richard
     
  7. apex1

    apex1 Guest

    You do´nt need the El. setup when you install a CPP Brian.

    When you look at my "trawler" thread, you´ll notice, that I am going to install a single (very heavy) Diesel and a CPP system. That engine can be operated at IDLE !!! for month, trolling at about 7 - 8 kn. And still provides full power for going "uphill" in severe conditions.
    http://www.boatdesign.net/forums/me...o-anywhere-trawler-build-side-side-28678.html
    And you know I like the kite assistance for passagemaking motoryachts.

    Regards
    Richard
     
  8. mark775

    mark775 Guest

  9. apex1

    apex1 Guest

    Largest possible prop size? (17% tip clearance)
     
  10. mark775

    mark775 Guest

    .74 m propellor diameter max.
     
  11. apex1

    apex1 Guest

    OK, next week.
     
  12. brian eiland
    Joined: Jun 2002
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    Location: St Augustine Fl, Thailand

    brian eiland Senior Member

    I've talked with Michael on a few occassions, and on one of those occassions he mentioned spending portions of the year in Sweden as his wife was from there.

    Apex had made the suggestion that Americans ignored the CPP subject, and I was simply pointed out that even while Mike is a US citizen and designer, his extra interest in the subject could arise from his Scandinavian contacts/ experiences.

    I was not suggesting anything about nationality in a detrimental manner, just making an observation. So what is this "like it or not" comment??
     
    1 person likes this.
  13. dskira

    dskira Previous Member

    I probably misunderstood you, I apologize for that.
    Cheers
    Daniel
     
  14. apex1

    apex1 Guest

    Some interesting reading here:

    http://setsail.com/picking-the-right-prop/#more-9835

    the Dashews are considering the third set of props on their Windhorse!

    The irony is, that they know about CPP´s and even mention them sometimes. Being far away from inexperienced they still have not choosen one.
    That shows how widely misunderstood and unknown the real advantages of this propulsion are.
     

  15. dskira

    dskira Previous Member

    In my personal opinion, I always thought the Dashew wrote to much, and this case they try to be the NASA engineers fixing a problem.
    But in that case it is so simple, call Richard, he will fix that in no time.
    Dashew are spending millions with specialists to fix something all fisherman knows for more that six decades, perhaps even more , its call CPP.
    The Dashew loves to complicate, for the sake of overdoing what is very simple. Yacht are not rocket sciences, sorry, no need to pretend it is. They are this particular breed of self guru, with I admit with a great deal of experience.
    They have a tendency to call their boat a revolution, they stated they use less fuel than on their sail boat. This is not a clever claim, quite idiotic at the matter of fact.
    I prefer to stay with Worth, Hisckok, Plyne, Coles, Fox, and DuCane as mentor on experience.
    Non of these persons will have put the galley and the saloon in the pilothouse on a multimillion 75' motor boat (Perhaps is not 75' I don't remember exactly)
    When I spend my night at the wheel I like to be by myself, in a dark pilothouse, with a little red ligth on the chart table and the very pale light on the compass and gauge. I don't want to have people with full light talking behind my back. I find the sea very in tune with the solitude, the peace and a shelfish pleasure and the safety of been able to see thru the window.
    At the end of the shift, I like to go down below, having a very different atmosphere, good smell of cooking and diesel, and the camaraderie of the crew.
    Or going to my bunk, far from light and noise, only the one of the sea, and the deep and reassuring sound of the engine.
    I don't like to mix the tasks of running a boat by having to steer a condominium.
    Happy new years everybody
    Daniel
     
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