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Twin 1000 hp C-18 Acerts: 46 GPH at 22 knots on 60 foot cat.

Discussion in 'Engines' started by YachtForums, May 3, 2011.

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  1. YachtForums, May 3, 2011
    #1
    YachtForums

    YachtForums Administrator

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    What say the experts...?

    "Twin 1000 hp C-18 Acerts: 46 GPH (combined) at 22 knots on a 60 foot catamaran hull."

    How do these efficiency figures compare to other boats you have run, mono or multi?

    (Purposely emitting brand and other performance figures)
  2. K1W1, May 3, 2011
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    K1W1

    K1W1 Senior Member

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    Hi,

    They won't be running for long at 1000 hp each which is a none too readily available configuration unless by special order.

    The published fuel consumption would suggest that they are developing about 500 hp a side
  3. CatTech, May 3, 2011
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    CatTech

    CatTech New Member

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    The combined fuel burn of 46 GPH indicates you are running the engines at a light load. Aprox 50%. I would say you are getting a decent speed out of the vessel for the load and fuel burn.

    As far as C18 acerts at 1000HP they are standard E rated engines used in many pleasure craft.
  4. YachtForums, May 3, 2011
    #4
    YachtForums

    YachtForums Administrator

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    Thank you for the feedback! I'm trying to draw a performance and efficiency baseline for comparative purposes. I knew the numbers were better than average for the stated speed, but how much better is affected by a myriad of factors. As the old disclaimer goes... "your mileage may vary".

    Thanks again.
  5. Bill106, May 4, 2011
    #5
    Bill106

    Bill106 Senior Member

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    Dug up some old sea trial numbers on a 61' planing mono hull sportfish (actually it's the boat in my avatar) with C-18 1015's (not the newer C18/A block but the original 3406 block). You didn't mention rpm's but as K1W1 said, they are pretty easy to estimate based on prop demand fuel consumption data. I can give you more specifics (weights, deadrise angles, etc.) if you want.

    Speed (K) RPM total gph fuel burn
    26 1600 45
    30 1800 60
    35 2000 82
    41 2300 100
  6. Capt J, May 4, 2011
    #6
    Capt J

    Capt J Senior Member

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    I believe it. As Bill106 stated, they are being run at a lower rpm and load facter than normal cruise. 1600 rpm's sounds about right. I know at 1950rpms, the 1015hp C18's burn around 72gph. Without me digging for seatrials I did on boats with c18's, 46 gph sounds correct at 1600rpms.

    I also believe the speed/fuel economy. I ran a 43' Lagoon cat- semi displacement hull, it cruised at 17 knots with twin 300hp volvo's and burned a little less than 1.5 GPM or about 23 gph. If it had a planing hull, it would've gone faster with the same fuel burn. So to see a 60 footer cruising at 22 knots at 46gph.......like 2.2 GPM definately sounds in range.
  7. motoryachtbill, Jun 21, 2011
    #7
    motoryachtbill

    motoryachtbill New Member

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    C-18's

    If you are going to use c-18's burning 23 GPH per motor have the builder do the math on some c-12's as well. I imagine the cat is sensitive to weight. Cruise fuel bern on one C-18 is 40GPH or so at 75%. WOT is 50GPH per side on C-18's. We just got a set of 1150 C-18's in a 57 and it does 31 knots in a semi displaement hull. Great running motors. I like the C-18 better than the c-12 in our boats, but in a lighter cat with a builder telling you low fuel burn numbers meaning his cruise speed is at 50% or so of the available power I would consider a smaller motor as well.