bigger props faster ship?

Discussion in 'Boatbuilding' started by Peter H, Feb 23, 2002.

  1. Kitlani
    Joined: Nov 2004
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    Location: Surrey, BC, CANADA

    Kitlani New Member

    Just jumping in here

    Greetings people,
    This is my first post on this forum and I haven't, as yet, searched all the forums categories, so if my question is redundent or mis-placed please direct me to a better starting place.
    I am working on a hand-pump powered kayak where the mechanism I've created will give me 75-150 revs on a flex-cable, per pump action. First, I am trying to find a supplier for small props, 2-6 inch diameter, preferably with a cowl around the prop. Secondly, does anyone know if there is any chart which may tell me the proplusion I can achieve with a small prop with limited horsepower, using different blade angles (rake?, feather?) Most of the info I've found is for 6" and up. Does anyone know of a small water-jet unit which might do the same. I am only after a typical kayak speed of 4-8 knots, nothing more exciting.
    I've worked on many design alterations and have been about 60 % successful over the long haul. Sailing, to me, offers up the most potential for creation, but motoring has its pleasures and unknowns too.
    Sorry if this isn't exactly 'on subject'. :(

    -ray-
     
  2. IanM
    Joined: Jul 2004
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    IanM New Member

    Mike D,
    Excellent work. I'm comparing several designs of larger ship, and need immediate propeller designs for my spreadsheets - any chance of refreshing your link to Oosterweld & Oossanen's paper? The link seems broken their end - not surprising for a 1975 paper, and your 2002 posting!

    Many thanks
     
  3. IanM
    Joined: Jul 2004
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    IanM New Member

    Timm,
    A copy of that spreadsheet would be more than welcome, - especially if received within the hour! no pressure of course (pun not intended!)
    I realise my timely request is only 2½years later
     
  4. hsie
    Joined: Dec 2004
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    Location: China

    hsie New Member

    indeed, the relation between the number of propellers and speed should be carefully studied, maybe you could read some about hydrodynamics,which could give you some basic ideas.

    But if you are not in the naval architecture,maybe it would be difficult for you.

    ChinaYacht@yahoo.com.cn
     
  5. pascal bertram
    Joined: Sep 2009
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    Location: thailand

    pascal bertram Junior Member

    hello
    as you looks very skylfull for propellers
    may be you got something for prop shafts calculation
    on a bertram 42 from 1984 as my probleme is to found the best middle solution with a prop shafts strong enough for 27 or 28 inches propellers and a package giving a little air to those 2 olds engines
    the thing is at that weight it is not easy to go over the hump
    - Displacement 39. 000 ton
    - dry weight 18800 kg
    - in charge 22000 kg
    -long total 12.95 mèters
    -long in the water 11.50 mèters
    - beam 4.23 meters
    - Beam in the water 3.85 meters
    - draft mini 0.83 meter to 1.22 meter maximum
    - hull V 17 degre deep
    - Bridge clearance 17.11 feet

    - Twin engine detroit diesel 671TI in line WITH compresseur TURBO AND INTERCOOLER the injecteur of 90 give
    325 hp each engine
    - The model 6-71(1062-4310)serial 6A287260 PORT et 6A287354 STED
    - GEAR BOX transmission Allisson manufactured by detroit diesel allisson Ratio 2.1
    serial 42708number 6770016 PORT M20Ra on the right and on the left serial 42416
    number 6770015 M20L
    - propeller shaft 1.3/4 inches
    - Cruising RPM 2100
    - Maximum RPM 2300 RPM WOT
    - Maximum RPM witout gear box in i mean only the engine runing is 2800 RPM
    thanks to everyone
    kind regards

    pascal
     
  6. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    I don't understand your question, but generally speaking I would go with thicker shafts for that setup. Detroit Diesels,though low on Horsepower for their size have a lot of torque. I would go with 2 1/4 shaft to be on super safe side.
     
  7. pascal bertram
    Joined: Sep 2009
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    Location: thailand

    pascal bertram Junior Member

    saft

    my question is connected to the fa
     
  8. pascal bertram
    Joined: Sep 2009
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    Location: thailand

    pascal bertram Junior Member

    my question is connected to the fact than on my iside of thailand there is no proper shipyard and no qualified tecnicien for those work like put a bigger shaft with all the glasswork it supposed.
    so i wonder if i could not found the same diameter but in a much better alloy which permited me to transmite the 325hp of every detroit diesel to a 28 inches diameter propeller by the way and in an other hand do you think it is possible to used aluminium propeller for that boat.
    kind regards
    pascal
     

  9. pascal bertram
    Joined: Sep 2009
    Posts: 30
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: thailand

    pascal bertram Junior Member

    my question is connected to the fact than on my iside of thailand there is no proper shipyard and no qualified tecnicien for those work like put a bigger shaft with all the glasswork it supposed.
    so i wonder if i could not found the same diameter but in a much better alloy which permited me to transmite the 325hp of every detroit diesel to a 28 inches diameter propeller by the way and in an other hand do you think it is possible to used aluminium propeller for that boat.
    kind regards
    pascal
     
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