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    cruising economy-gctid370310

    I am a new boater. I drove my 91 3058 Motoryacht approx. 70 miles. I was cruising at 3600 rpm's at approx. 17-19 knots. I was getting .75 gpm. I have a single 7.4 litre 454. Is this what I should expect for fuel economy? The ocean conditions were perfect, smooth as glass. Doug /SanDiego

    #2
    My 2556, which is 28' overall, is powered with a single 5.7 using a 4 barrel carb. It gets 1.7 mpg unless the electric choke is bad, then it gets 1.0 mpg. This is at 3400 rpm at about 17 to 19 knots

    [img]/media/kunena/attachments/vb/673722=26347-Underway.jpg[/img]

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      #3
      0.75 gallons/mile is about 1.3mpg if that's what you meant in your post. While nothing to write home about, it's not that bad for a carbureted engine on a boat that size.
      2007 Discovery 246
      300mpi BIII
      Welcome island Lake Superior

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        #4
        How much worse is it having twin engines vs. single ?

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          #5
          doug woods wrote:
          I am a new boater. I drove my 91 3058 Motoryacht approx. 70 miles. I was cruising at 3600 rpm's at approx. 17-19 knots. I was getting .75 gpm. I have a single 7.4 litre 454. Is this what I should expect for fuel economy? The ocean conditions were perfect, smooth as glass. Doug /SanDiego
          That was about the best I ever did with my 3058. Usually I ran closer to 1 gpm. It's a big boat for a single engine. Twins will get better mileage in that hull, but then you have added maintenance of 2 engines and outdrives. Everything is a compromise..

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            #6
            Impulse wrote:
            How much worse is it having twin engines vs. single ?
            Not much and if a boat is under powered with a single it might even be better. My Contessa got about 1 1/2 mpg with twin 5.0's unless it was very heavily loaded. Then about 1.3 mpg.

            Doug
            Started boating 1955
            Number of boats owned 32
            Bayliners
            2655
            2755
            2850
            3870 presently owned
            Favorite boat. Toss up. 46' Chris Craft, 3870 Bayliner

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              #7
              First point of clarification: In general are you guys using statue miles or nautical miles?

              I use nautical miles as that is what I navigate in per the charts.

              So my 2855 7.4 mpi at 3700 rpm I get 1.55 nm per us gal. At 3600 I get 1.48 nm per US gal. as measure with fuel flow meter with gps attached. I have a Lowrance LMF400
              John McLellan White Rock BC
              "Halifax Jack"
              1999 2855 383 stroker BII
              MMSI 316004337

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                #8
                Remember that there are basically two efficient speeds...... hull speed..... and planing speed.

                If cruising at 3600 rpm's at approx 17-19 knots is not fully up on plane, you will not achieve the optimal fuel economy.

                Anything in between is pretty much waisting fuel and burdening your engine.

                .
                Rick E. Gresham, Oregon
                2850 Bounty Sedan Flybridge model
                Twin 280 HP 5.7's w/ Closed Cooling
                Volvo Penta DuoProp Drives
                Kohler 4 CZ Gen Set

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                  #9
                  My 32 averages about one nautical mile per gallon. I don't have flow meters. I base it on how far we traveled and how much gas it takes to refill the tanks. This method has been fairly accurate over the last four years we've owned the boat.......close enough anyway.

                  Lets face it, the word economy shouldn't really be used when talking about boats. There's nothing economical about them........unless your the guy selling the gas or doing the work on them.

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                    #10
                    fuel economy and boating should never be used in the same sentence........op

                    :arr arrrrr

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                      #11
                      Impulse wrote:
                      How much worse is it having twin engines vs. single ?
                      Actually not much as I get 1.20-1.25 mpg on Midnight Sun. Towing the Wave Runner at cruise drops this to 1.1

                      OK, I am sick at home and bored so let's let reality sink in. Let's assume 1 mpg and 30mph cruise. Cruise for 1 hr, cover 30 miles and consumes 30 gallons x $4.50 a gallon is $135/hr. Crap, my boat makes more than I do.
                      Cheers, Hans
                      2007 Carver 41 CMY
                      Twin Volvo D6-370
                      Montreal, Canada
                      Midnight Sun I Photos

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                        #12
                        MidnightSun wrote:
                        Actually not much as I get 1.20-1.25 mpg on Midnight Sun. Towing the Wave Runner at cruise drops this to 1.1

                        OK, I am sick at home and bored so let's let reality sink in. Let's assume 1 mpg and 30mph cruise. Cruise for 1 hr, cover 30 miles and consumes 30 gallons x $4.50 a gallon is $135/hr. Crap, my boat makes more than I do.
                        Lottsa luck thinking $4.50/gal this summer......I am expecting to see about $7.50 per CAN gallon this summer up here (approx $1.70/L)

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                          #13
                          Spitfire wrote:
                          Lottsa luck thinking $4.50/gal this summer......I am expecting to see about $7.50 per CAN gallon this summer up here (approx $1.70/L)
                          I cheat, other side of the river is cheap US gas.
                          Cheers, Hans
                          2007 Carver 41 CMY
                          Twin Volvo D6-370
                          Montreal, Canada
                          Midnight Sun I Photos

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                            #14
                            MidnightSun wrote:
                            I cheat, other side of the river is cheap US gas.
                            as they say "location, location, location"......lucky you.

                            Will think of you every time I fill up.....

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                              #15
                              Spitfire wrote:
                              as they say "location, location, location"......lucky you.

                              Will think of you every time I fill up.....
                              I will return the favour and think of you when I fill up. :drama
                              Cheers, Hans
                              2007 Carver 41 CMY
                              Twin Volvo D6-370
                              Montreal, Canada
                              Midnight Sun I Photos

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