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Performance tests

Discussion in 'General Yachting Discussion' started by CaptCook, Oct 30, 2013.

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  1. CaptCook, Oct 30, 2013
    #1
    CaptCook

    CaptCook New Member

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    I'm doing a performance test comparison of a few SFMY. I looked at bunch of sites and the numbers are all over the place.

    Are there any standards in perf. testing at all?
    What would be the most reliable and consistent source of information?
  2. Capt J, Oct 30, 2013
    #2
    Capt J

    Capt J Senior Member

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    I did a lot of them for Cabo several years back. The standard Cabo used was, no trim tabs were used whatsoever. However fuel and water was whatever it was in the tank and most boats didn't have a hardtop or outriggers or such, just because the engine startup/test was done first before pipewelders installed the dealer or owner ordered top etc.
  3. CaptCook, Oct 30, 2013
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    CaptCook

    CaptCook New Member

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    Capt J, I compared some Cabo flybridge and Tiara 3800 performance numbers at optimal cruise and hull speeds. Please let me know if they make sense to you and if you can add anything. I'm leaning more towards the medium-size Convertible like Cabo 38 or 40 as having the best fule-efficiency in comfortable looking package.

    Tiara 3900, CAT C9 575hp (2 ppl, tanks full, 1ft, 2-5 knots wind):
    cruise 25.5 knots (2096 RPM), 38.8 gph, 0.76 mpg

    Cabo 38 Flybridge , MAN 800hp (prefer CAT C9-12):
    cruise 28 knots (1750 RPM), 40 gph, 0.8 mpg

    Cabo 40 Flybridge, CAT C12 710hp (6 ppl, tanks full, no HT/Enclosure, flat, no wind):
    cruise 30.5 knots (2000 RPM), 44.7 gph, 0.7mpg

    Cabo 43 Flybridge, CAT C12 710hp (4 ppl, tanks full, with HT/Enclosure, 1-2ft, 10kts wind):
    cruise 28 knots (2100 RPM), 55.7 gph, 0.5 mpg

    Cabo 48 Flybridge, CAT C18 1015hp (6 ppl, tanks full, with HT/Enclosure, 2ft, no wind):
    cruise 29 knots (2100 RPM), 74 gph, 0.4 mpg
  4. PacBlue, Oct 30, 2013
    #4
    PacBlue

    PacBlue Senior Member

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    The answer is NO, there are no standards adhered to in the marine industry for performance tests. Everyone has there own twist.

    As a consumer, the data that should matter the most to you is one taken at Full Load (Fuel/Water, no Waste) an allowance for owner's gear (including dinghy/crane) and preferably with a tower/enclosure if that's the way you are going to operate. Basically the worst case scenario.

    Trials taken in South Florida in Summer would also represent a worst case scenario, as winter trials in other regions can through a wrench into data if you are eventually running in warm climes.

    Have not even touched upon how the data is collected. Best to have your own hand held that you can believe in as some Broker supplied readings could be calibrated on the "optimistic" side.

    Good Luck :)
  5. Ormond Bert54, Oct 30, 2013
    #5
    Ormond Bert54

    Ormond Bert54 Senior Member

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    Here is mine.
    1984 Bertram 54 12V71TI Engines, 20 knots cruise @ 66 GPH

    I changed to new 4 blade Michigan Wheel DQX props this summer and believe I have experienced a significant increase in fuel economy. This is the result.
  6. CaptCook, Oct 30, 2013
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    CaptCook

    CaptCook New Member

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    I think Bertram is looking for help right now. :)
  7. CaptCook, Oct 30, 2013
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    CaptCook

    CaptCook New Member

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    It reminds me again EPA testing of car performance. Stated MPG never match the real world numbers.
  8. PacBlue, Oct 30, 2013
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    PacBlue

    PacBlue Senior Member

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    One thing to keep in mind if you are comparing engines of different rpms is to create your own table using the published test data but by taking the rpm's and dividing them by the max rated engine rpm.

    You will then get speed or fuel consumption as a percentage (%) of throttle, making it easier to understand the results. You can then check and see what the data is at say 80% throttle for a variety of engines.
  9. Ormond Bert54, Oct 30, 2013
    #9
    Ormond Bert54

    Ormond Bert54 Senior Member

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    I don't understand. I am genuinely impressed with the performance.

    20 knots at 66 gph = approx .3 MPG Seems pretty good for moving so much boat at a good clip. I think it does some serious damage to the argument of "current technology diesel is so much more fuel efficient that it almost pays for the repower..."

    And regarding size ... I think the 54 is just big enough. It would be nice though to have a 63'
  10. Capt J, Oct 30, 2013
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    Capt J

    Capt J Senior Member

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    Yes, the 40' Express also does 30.5 knots with C12's and hardtop/enclosure and 6 people at 80% load. 45' Cabo with C18's does 30.3 knots with tuna tower/riggers/enclosure. The 48' FB with gear/hardtop/riggers/ and 6 people cruises at 27.5 knots with C18's 1015hp same fuel burn. 44 Cabo with c18 acerts/ tuna tower/riggers/enclosure cruised at 33 knots at 80% load and 85gph. 40' Zues express is 32 knots at 45gph (tuna tower,riggers, full fuel), same boat with 800 hp mans is 60gph, same speed.
  11. PacBlue, Oct 31, 2013
    #11
    PacBlue

    PacBlue Senior Member

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    I recall seeing a 54 Bertram ("Sugar Bear") repowered in 2003 with 825hp Series 60 engines, getting 22 knots at 1900 rpm, 50gph total.
  12. AMG, Oct 31, 2013
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    AMG

    AMG YF Moderator

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    Hmm, our new 80-footer with triple 900 hp (3xIPS/1200) is taking 45 gallons (170 litres) at 20 knots...
  13. Capt Ralph, Oct 31, 2013
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    Capt Ralph

    Capt Ralph Senior Member

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    What RPM were you spinning? I would think 66gph near the upper rpm limit. Any cruise data?
    ,rc
  14. Capt J, Oct 31, 2013
    #14
    Capt J

    Capt J Senior Member

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    The 825 hp Series 60's burn between 63-65 GPH at 1900 rpm's.
  15. Capt J, Oct 31, 2013
    #15
    Capt J

    Capt J Senior Member

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    The 75' Hatteras MY I ran for years with 12v71TI's would burn 80 gph at 1900 and 90gph at 2000 rpms
  16. Capt Ralph, Oct 31, 2013
    #16
    Capt Ralph

    Capt Ralph Senior Member

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    Was that the 650hp or 800/900hp tune?
  17. Capt J, Oct 31, 2013
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    Capt J

    Capt J Senior Member

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    I don't think TI's are 650hp in any configuration.......They were 8something.....835hp rings a bell.
  18. Capt Ralph, Oct 31, 2013
    #18
    Capt Ralph

    Capt Ralph Senior Member

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    650hp is the stock DD 12v71ti tune with N90 injectors and dry turbos.

    80Gph (total ship) sounds about rite for well loaded 800/850hp tune under a good (not max) load.

    The old rule; 1/10 gph per hp per hour /2 (per engine); is pretty close for turbo 4 strokes, add just a tage (Small fart factor) when talking big hp 2 strokes.
    Roughly, your 835 hp DDs under good load was consuming near 80 gph. At WOT, I could see 90gph total.
    MPG still sux, we may not want to go there...
  19. Capt J, Oct 31, 2013
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    Capt J

    Capt J Senior Member

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    They definately had 110 injectors, not 90's. 90's are a real good injector in the 8v71TI's instead of the 110's. They run incredibly clean and nice/perky with them.