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Detroit 12V71

Discussion in 'Engines' started by Sam Bellows, Apr 13, 2022.

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  1. Pascal, Apr 13, 2022
    #21
    Pascal

    Pascal Senior Member

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    Combined. See my last reply. I never include gen because i run the gen 24/7 so I keep track of that burn separately.

    the key is to not exceed hull speed. For a 67 footer hull speed is going to be 10kts. Not 10.5 kts… an extra 1/2 kts above HS will Cost you 30% more fuel. An extra knot? Close to double
  2. Capt Ralph, Apr 13, 2022
    #22
    Capt Ralph

    Capt Ralph Senior Member

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    HP is fuel
    Crudely, if each engine is delivering 250 HP to the same props and same ratios, Yes.
  3. Capt Ralph, Apr 13, 2022
    #23
    Capt Ralph

    Capt Ralph Senior Member

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    Hull speed can be calculated by the following formula:
    v h u l l ≈ 1.34 × L W L {\displaystyle v_{hull}\approx 1.34\times {\sqrt {L_{WL}}}}
    [​IMG]

    where
    L W L {\displaystyle L_{WL}} [​IMG] is the length of the waterline in feet, and
    v h u l l {\displaystyle v_{hull}} [​IMG] is the hull speed of the vessel in knots
  4. Sam Bellows, Apr 13, 2022
    #24
    Sam Bellows

    Sam Bellows New Member

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    I wholeheartedly appreciate your willingness help and give me some numbers to go on. Im a diver and the ability to use it as a live aboard not to mention a dive boat or occasionally as a chartered dive boat and run it kinda affordably, I’m not expecting a half gallon an hour, is rather important. I’m wanting the yacht equivalent of a Chevy suburban. The places I’d like to go in the Caribbean and gulf are far enough out I don’t want to do it in a 30’ bathtub.
  5. rusty882000, May 12, 2022
    #25
    rusty882000

    rusty882000 New Member

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    Any idea what the Detroit 12V-92TA 8122-7400 rated shp 775@2300 rpm would burn at 1800rpm cruising?
    Cant find any performance data on this engine.
  6. Capt Ralph, May 12, 2022
    #26
    Capt Ralph

    Capt Ralph Senior Member

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    Correctly loaded, 34 (US)GPH.
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