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I'm Hoping Someone Can Check These Statistics.

Discussion in 'Technical Discussion' started by LAST HOPE, Dec 11, 2015.

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  1. Capt J, Dec 24, 2015
    #41
    Capt J

    Capt J Senior Member

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    I believe most all of the ones from 2005 with the electronic displays are very very accurate. But they use a calculation based on what the fuel injectors are putting out.
  2. PacBlue, Dec 25, 2015
    #42
    PacBlue

    PacBlue Senior Member

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    Have not seen your 1 page chart, but the manufacturer's data gets scrubbed quite a bit and should be fairly accurate. You need to take the fuel consumption of the Cubic Propeller Curve data, as this is the predicted values for fuel consumption under load, you may be reading the data straight of the dyno run which is not the same.
  3. Capt J, Dec 25, 2015
    #43
    Capt J

    Capt J Senior Member

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    No, from the propellor curve chart. I don't have the brochure in front of me, I left it on the boat, but picked it up from the dealer about 6 months ago. It showed 6 gph at 1200 rpms for the 425 hp, and I think 8 gph at 1400 rpms. The 1200 rpms figure was way off, it showed around 1.8 gph at 1200 rpms for the 350hp motor.
  4. PacBlue, Dec 25, 2015
    #44
    PacBlue

    PacBlue Senior Member

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    Find it and post it, I would like to see it.
  5. Capt J, Dec 25, 2015
    #45
    Capt J

    Capt J Senior Member

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    http://s121.photobucket.com/user/osd9/media/3126-TA420data.jpg.html

    It's showing 6 gph at 1200rpms for the propellor curve, yet every other brochure from CAT on the 3126B 420HP propellor curves show 2.2 gph (I think) at 1200 rpms for the propellor curve. The odd thing is if you look at 1600 rpm's on the same prop curve chart it's showing 5.9 gph consumption so it must be an error. This is from the brochure I picked up at the dealer 6 months ago, 2 sided 1page color brochure that has the prop curves for both 375hp and 420hp on the same brochure.
  6. PacBlue, Dec 25, 2015
    #46
    PacBlue

    PacBlue Senior Member

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    Try this sheet instead, that data you provided looks corrupt...

    Attached Files:

  7. Capt J, Dec 25, 2015
    #47
    Capt J

    Capt J Senior Member

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    I'm telling you that that is the information on the remanufactured CAT 3126 brochure for both 375hp and 420hp (they had both prop curves, hp curves on the same sheet) from the CAT dealer that I picked up. Yes, I agree it is wrong, but it is the one in a large dealership.
  8. Marmot, Dec 26, 2015
    #48
    Marmot

    Marmot Senior Member

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    That spec sheet is really screwed up ... D4594 is for a 3512 genset engine with a max speed of 1200 rpm.

    It looks like some marketing guy mixed up his tables ... and/or his math. The BSFC figure should wave a huge red flag for anyone familiar with diesel engine fuel consumption and efficiency numbers. That 1.2 number looks more like that of a nitro fueled race car or a very small gas turbine.
  9. LAST HOPE, Jan 24, 2016
    #49
    LAST HOPE

    LAST HOPE New Member

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    I'm thinking this may well be the largest hurdle to the whole project, just explaining the concept to those connected with traditional sailing, up to now, is a major frustration. (I'm also thinking that some see anything different, as a threat of some sort).

    I do now have someone in the wind turbine industry onboard, so maybe, just maybe, things could be moving forward. (It took a lot of explaining though).
  10. Marmot, Jan 24, 2016
    #50
    Marmot

    Marmot Senior Member

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    Keep in mind that those calculations were made in a test cell and involve a clearly defined set of conditions that may or may not actually exist on any boat installation and may not have existed in the test cell when the data was obtained.

    Read the small print at the bottom of a spec sheet ...
  11. Capt J, Jan 24, 2016
    #51
    Capt J

    Capt J Senior Member

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    I understand that. But, in real life I've found most of all of the electronic displays fuel consumption readings to be very accurate. With the CATs you can burn through 1000 gallons of fuel and you'll be within a gallon of what the display is telling you, you've burned from what I've seen. MANs and MTU I've seen the electronic displays accurate as well.

    As for the fuel burn charts for the mechanical diesels, they're pretty accurate the vast majority of the time providing the boat is propped to achieve WOT rpms......but like anything, not exact.
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