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newbie would appreciate some fuel Economy thoughts!-gctid340504

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    newbie would appreciate some fuel Economy thoughts!-gctid340504

    Hi, I've been a looker forever and took the plunge on a very clean 1986 2550 with the AQ260 and a VP280 drive on it. By everything I can see and tell the drive train is stock.

    Without going into the engines internals are there some basic suggestions concerning alterations to improve my fuel economy. The boat is a life long pacific Coastal toy. has new bottom paint and matching new drive. n motor has less than 100 hrs on the top end about 800 hrs on the bottom end but opened up and inspected, always very well maintained. i'm an airplane mechanic and chevy based hotrods but your insight would be great. I'm fine with the performance levels and use a floscan and all it does is scare my check book.

    Prop suggestions?

    Distributer ? type or timing suggestions?

    carb? 4 barrell dialed in vs same cfm 2 barrell, Vac. or mechanical on the 4 barrell?

    Any thing?

    Thanks in advance, happy camper regardless,

    Rory

    #2
    first off...welcome to the zoo...secondly.....boat and economy should never be used in the same sentence.....the term boat= break out another thousand...sooo...good luck with the economy thing.....out here in the pacnorwest ....there are just too many variables to give you an accurate estimate on an older boat...other than putting in an mpi engine...ain't much you can do to improve "Economy" other than slow down or find the sweet spot of the boat and run it there......

    but best of luck with the new toy..

    :arr arr

    Comment


      #3
      I just did a run over the weekend and my sweet spot was 3400 rpm at 30 mph at 10.2 gph

      This was on unusually flat water for my area.

      That is GOOD mpg for a small block powered 24 foot planning hull.

      Don't chase your tail trying to get anything over 2.9 MPG, it won't happen. You will probably be in the 2.3 mpg range.
      " WET EVER "
      1989 2459 TROPHY OFFSHORE 5.8L COBRA / SX
      mmsi 338108404
      mmsi 338124956
      "I started with nothing and still have most of it left"

      It's only a rock, get over it.

      Comment


        #4
        The only way economy is a good word for a boat is just below hull speed. In your boat maybe 6 mph max. Any more and the fuel usage can double in as little as 1 mph.

        For the best speeds on plane, your flow scan will show you the best economy. It won't be just on plane and use of trim tabs will make a difference.

        You need to go a bit faster than just on plane. The goal is to get as much of the boat out of the water as possible. It should result in the hull out of the water about your pilots seat. That is a rough estimate but I think you will find it close.

        It isn't how much fuel you burn but what you do while doing it. Faster of course will result in more gallons per hour but you also go more miles. Often much better mpg than going slow. 10 mph for example is usually about the worst speed. You push a lot of water and use a lot of gas doing that. You will not save money going that speed. It will cost you more.

        If it is just a boat ride, 6 mph is different but its fun. Quiet, easy going if the waters are calm. You can relax and enjoy the ride.

        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

        Comment


          #5
          Welcome to the BOC.

          Not sure where to begin...

          Planing:

          be sure that your AQ series Volvo Penta 280 drive "set pin" is in the center position.

          best planing attitude will be on-plane and then some.... IOW, get the hul on top of the water, and a bit more so.

          keep the stern light by placing stowed items forward. Stern heavy hulls struggle to get and remain on plane.

          if curious, learn what you can about the V/P Duo Prop. It can be a bolt-on addition for your drive.

          As you know, with piston Aircraft Engines, Ignition Timing is critical.

          Same with the Marine Gassers.

          Not sure if Detonation is of the same concern with piston aircraft engines...., but it is an extreme concern with marine loads.

          See your OEM specs for your engine, and time the engine for TA or TAT (total advance or total advance timing) of which is generally at/near 3.2k rpm.

          The curve will be rather linear.

          Not that you asked.... but NO diaphragm vacuum advance ignition.... it is unnecessary and is relatively ineffective.

          Your V/P OEM carburetor secondary throttle plates open manually, but the above restriction plate (aka gate or door) opens via manifold pressure assuring the "On-Demand" or "As-Required" principle.

          It works well.

          Looks like you have a FFM (fuel flow meter).

          GPH is rather meaningless without as associated distance traveled.

          MPG gives us a meaningfull means of fuel units.

          Enjoy the boat and boating!
          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

          Comment


            #6
            Great info thanks much, any thought on a happy medium for a prop since i really can't afford the DP conversion yet?

            Some where someone mentioned a 17dia x 14 pitch or something close.

            Not the kind of props I'm a custom too.

            Thanks again,

            rory

            Comment


              #7
              I used to run a 15x19 on my '86 2450, which is 1 foot shorter and 1 foot narrower. I would consider looking at some Contessa threads where they talk about props...a lot of them bumped up to 16 inch diameter props and backed off the pitch somewhat.

              Long term, the 2550 Cieras really need the DuoProp drives, and hardly any of them got them. I would save up your money and swap to the DP drive as soon as possible.

              Enjoy....I LOVE the 2550 and would love to own one someday.
              Matt Train
              BOC Site Team
              Chicagoland, IL

              Comment


                #8
                Rory, which 2550 is this........ the SDN F/B or the SB version?
                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

                Comment


                  #9
                  dmcb wrote:
                  The only way economy is a good word for a boat is just below hull speed. In your boat maybe 6 mph max. Any more and the fuel usage can double in as little as 1 mph.

                  For the best speeds on plane, your flow scan will show you the best economy. It won't be just on plane and use of trim tabs will make a difference.

                  You need to go a bit faster than just on plane. The goal is to get as much of the boat out of the water as possible. It should result in the hull out of the water about your pilots seat. That is a rough estimate but I think you will find it close.

                  It isn't how much fuel you burn but what you do while doing it. Faster of course will result in more gallons per hour but you also go more miles. Often much better mpg than going slow. 10 mph for example is usually about the worst speed. You push a lot of water and use a lot of gas doing that. You will not save money going that speed. It will cost you more.

                  If it is just a boat ride, 6 mph is different but its fun. Quiet, easy going if the waters are calm. You can relax and enjoy the ride.

                  Doug
                  +1 Spot on.

                  Comment


                    #10
                    2850Bounty wrote:
                    Rory, which 2550 is this........ the SDN F/B or the SB version?
                    It's a 1985 Designers edition , not a flybridge

                    rory

                    Comment


                      #11
                      rorysd wrote:
                      It's a 1985 Designers edition , not a flybridge

                      rory
                      GREAT BOAT! Welcome to the zoo.

                      And +1 on what Doug said.

                      Sit back and enjoy the ride, at whatever speed you choose.
                      Phil, Vicky, Ashleigh & Sydney
                      1998 3055 Ciera
                      (yes, a 1998)
                      Previous boat: 1993 3055
                      Dream boat: 70' Azimut or Astondoa 72
                      Sea Doo XP
                      Sea Doo GTI SE
                      Life is short. Boats are cool.
                      The family that plays together stays together.
                      Vice Commodore: Bellevue Yacht Club

                      Comment


                        #12
                        Yeah I gave up on whatever fuel costs. For something that gives me this much enjoyment, there'll always be a way.

                        Comment


                          #13
                          As a maintenance item a nice smooth clean hull improves fuel economy.

                          As said above your best economy is running at hull speed. About as fast as you can go without a wake, 6-7 MPH.

                          ((For our boat this is about 2.5 MPG))

                          Stay out of the range where you are nose high pushing water but not planing.

                          ((For our boat this can be as poor as .5 MPG))

                          Once on plane and skimming your MPG economy is pretty constant.

                          ((For our boat from 3300 to 4000RPM our MPG stays about 1.1 MPG. Above 4000RPM economy starts falling off.))
                          Jim McNeely
                          New Hope a 2004 Bayliner 305 Sunbridge Express Cruiser
                          Twin 5.7s with Bravo2 drives
                          Brighton, Michigan USA
                          MMSI # 367393410

                          Comment


                            #14
                            +1 on Doug's comments also.

                            The only way to save fuel is to leave it on the trailer as some have done in Portland and dream about boating. It is far better to budget for the year say $5,000.00 and stick to it, put that money in a boat fund year round and stick to that amount. You can also do the same for toys or additions to the boat, even slip fees.

                            I spent 7 weeks in the North Channel 2 summers ago and will again this summer, 7 weeks $2,200.00 on gas and $600.00 for food and a few hundred on beer and booze. I have no idea where I could stay for 7 weeks for about 3 grand for 2 in a 5 star hotel.

                            Ken
                            Watching crow being slowly eaten in the PNW.
                            The village idiot strikes again.

                            Comment


                              #15
                              can't add anything to what's already been said, just wanted to say great choice in boat and congrats! I love my 2550

                              Comment

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