The Controllable Pitch Propeller, a summary.

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

  1. TollyWally
    Joined: Mar 2005
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    Location: Fox Island

    TollyWally Senior Member

    Well put
     
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  2. apex1

    apex1 Guest

    Like every other old saltbuckle Daniel, well observed! The ever so popular bench at the wheelhouse, is a nice place for guest and crew, and a pain in the *** for the man at the wheel. On my boats that was either not there, or off limits in severe weather and after dark!

    The statement that sailing can be (and often is) more expensive than motoring is my experience too, though!
    And Windhorse is 84´

    Regards
    Richard
     
  3. thudpucker
    Joined: Jul 2007
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    Location: Al.

    thudpucker Senior Member

    I like the dark and solitude of night cruising as well.
    With the hold full and headed back to port in the dark, I'd get kind of nervous.
    The dark transit with some good luck behind me began to make me strain to 'see' obstacles that weren't there.
     
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  4. dskira

    dskira Previous Member

    Of course you right Richard. I should have refered to classic sailing yacht and sail boat without systems. A dying breed :!:
    Not the modern one who have their generators turning all the time to keep the hydrolics and hotel sysem running. And also recharging a big bunch of batteries is expensive in fuel.
    Turning a numbers of electricals large winches is very demanding in consumption from the genset or the hydropack. It always come back to fuel!
    I forget we are on the 21 century :D
    Cheers
    Daniel
     
  5. apex1

    apex1 Guest


    Of course you´re right as well Daniel!

    The old gaffer with a simple forest on deck outperforms every modern production boat in terms of cost (and maintenance too). Having a coal stove, petroleum lamps and a handpump for the galley is not to beat.
    But, you know, we like our beer cold today, and our shower hot! Some like even having a sniff all year round at the expense of a brandnew car. (I mean Aircon. at freezing level, so common on US boats)

    The joke behind the plain truth is, that these "old" boats, built in modern ways, outperform almost ALL of the modern production junks, in the hands of the right people.


    We have (or had?) a regatta in Hamburg every Winter, yes Winter! The "Konsul Klöben Regatta" a pure fun contest, but taken very serious. The Regatta starts at the second weekend in December! The main participants are old museum ships and traditional sailors. Many old workhorses amongst them.
    The first price is a cabbage! (impressively processed into a delicious stew shortly after the winner is clear)

    The Regatta was (or is) open for each and everyone. In some years modern boats participated. They gave up soon, always the old workhorses were in front! ALWAYS !!! The oldest winner was a little pilot schooner from 1889!
    still exists! I found this: http://www.prachtvoll.de/08/regattaelbe/default.aspx
    http://www.betty-ck145.de/gallery2/embeddphotoengblue.php?g2_itemId=26
    and some of them:http://www.museumshafen-oevelgoenne.de/museumshafen-oevelgoenne/index.html

    Our grandparents cannot all have been ******.

    Regards
    Richard

    ähh.....are we off topic now??
     
  6. dskira

    dskira Previous Member

    Thanks for the link Richard.
    Yes it worth it to be off topic just to see this beauty.
     
  7. apex1

    apex1 Guest

    All of them have been abused, neglected, scuttled, rebuilt to absurdity and finally restored to their best ages.

    Find someone to sail with you on a modern plastic sampan, you´ll have a problem.


    These old workhorses have a face, that makes the people ask for giving a hand!

    Yes we are off topic, so be it! But some of the old knowledge lead to the conclusions about a sensible propulsion. Some of these old boats are nothing but the predecessors of todays fishing fleet. So we are not too far off the path! And its my thread anyway.

    Regards
    Richard
     
  8. RHough
    Joined: Nov 2005
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    Location: BC Summers / Nayarit Winters

    RHough Retro Dude

    For aircraft don't they use the same idea? The constant speed propeller?

    Hamilton Standard dates to 1929 IIRC.

    There is obviously a proven market for Variable Pitch Propellers. After scanning half a dozen of the links provided, the systems seem to be for displacement hull types? If there were examples of CPP drive systems for a 40-50 planing design I must have missed them.

    The fuel curve for my boat in distance per volume (km per litre or miles per gallon) shows a near linear slope to about speed/length 1.3:1 then drops about 50% and remains near constant from about S/L 2:1 to 4.2:1 (80% load) and drops at speeds above that.

    8 knots cruise gives about 750 mile range. 12 to 26 knots gives about 310-335 mile range.

    Has anyone looked at CPP's for this sort of application?
     
  9. thudpucker
    Joined: Jul 2007
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    Location: Al.

    thudpucker Senior Member

    Controllable pitch and Constant speed are two different things. Both are used on Aircraft.

    With Controllable pitch, you can set an Rpm. Then run the torque driving the boat right up till the engine starts to heat up a little. Then back off till everything is in the green and be satisfied you are getting the best of all things from your boat and prop.
     
  10. apex1

    apex1 Guest

    Do´nt get it wrong here.

    We do´nt have aircraft applications in a boat!

    What did you assume? I open a summary whithout knowing the results?

    A CPP is a proven propulsion (well not a common one) in fast planing craft as well.

    In fact it is the far superior propulsion in fast craft.

    you get faster over the hump and remain much more and easier in the economical range with a CPP than with a FPP.

    Regards
    Richard
     
  11. Fanie
    Joined: Oct 2007
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    Location: Colonial "South Africa"

    Fanie Fanie

    Hi Richard,

    Any chance of a summary of suppliers of these props ?
     
  12. apex1

    apex1 Guest

    You know that there was some sort of holiday in the civilized part of the world?
     
  13. Fanie
    Joined: Oct 2007
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    Location: Colonial "South Africa"

    Fanie Fanie

    It's still on here :D

    Would that affect the list ?
     
  14. RHough
    Joined: Nov 2005
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    Location: BC Summers / Nayarit Winters

    RHough Retro Dude

    Propellers in fluid (air or water) work the same. They are either airscrews or waterscrews, are they not?

    Variable pitch is one thing, some variable pitch screws can also be constant RPM.

    I assumed nothing, why the attitude? I opened 5 or 6 of the links you provided and did not see an application that answered my questions, so I asked here in the forum.

    The power requirement changes with speed. I struggle with the idea of maintaining a load on an engine rated for 500HP at 6 knots and at 30 knots. Is the idea to allow the engine to turn 1500 RPM instead of 800 RPM at 6 knots? Doesn't the internal loss from friction increase with RPM? I get that reducing pitch at idle allows you maintain a lower speed. I can see the pitch required to allow the engine to reach rated RPM can change with load and conditions. I can see the value in such a system.

    I won't give it another thought after your response.

    Excuse me for living.
     

  15. Submarine Tom

    Submarine Tom Previous Member

    Here we go again.

    Well, this thread was good while it lasted.

    Bye-bye,

    -Tom
     
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