Fuel Flow Meters

[cbadmin]

From: MichaelOnTheClaraMae (Original Message) Sent: 1/17/2003 4:06 AM
>>You have a fuel flow meter? curious what you burn at say 18 mph cruise with the Honda my Yamaha 115 (2-stroke)sucks about 8 gph at that speed with three people and full load of fuel and water. I tend to average between 2 and 2.5 mpg. overall.

steve

From: MichaelOnTheClaraMae Sent: 1/17/2003 4:23 AM
Steve,

I don't have a fuel flow meter and so far don't even have a guess on Gal/Hr or MPG running my Honda BF130 on the CD-25. Most of the 20+ hours on my engine have been in high winds and rough water. I really haven't tried to take a measurement thus far. I have seen 2 to 2.5 MPG mentioned by some other CD-25's running twins, so I don't think you are too far out of line.

I plan to do make some long distance trips in the months to come and a fuel flow meter would be a welcome addition. Do you have one? What would you recommend?

Michael (Clara Mae)

From: Sundown Sent: 1/17/2003 6:51 AM
I recently repowered my '86 22' Angler with a Mercury 115 HP four stroke EFI. Currently, I am running a 15" prop. I also installed a new custom aluminum 29 gallon tank and a Navman fuel flow meter. This model has come down in price since I purchased it. Sadly, I was only able to put a few hours on the motor (mostly after dark and at slow speed) since I installed the Navman because the lake has frozen. At idle, I am seeing .1 to .2 gph. At 3,000 rpm and 15 mph, I am seeing around 3.0 gph or 5 mpg. These units are really useful in confirming the best trim position at a given rpm/speed. For example, you can see how much efficiency you lose by bringing the bow down to stop the pounding in a light chop. It seems to be very accurate in reading "fuel used" and "fuel remaing." At least, it compares favorably with my dash mounted fuel gauge and is probably more accurate. When the lake thaws, I will get a chance to put up some more numbers. There is a Flow Meter thread on the CB's you can check out for additional info.
Larry

From: stevej Sent: 1/17/2003 7:08 PM
Larry thanks for posting the links to the fuel meter thread & Navman site I was going to say do a search but that's one of the great thing about this site everbody is willing to help out.

Michael Shearwater came with a Flowscan and I would not without one now. Two big advanatges over the standard fuel guage. They are very accurate so you know exactly what remains in the tank the other is trim adjustment, does not take much adjustment with the tabs or motor to see fuel use vary as much as 2 gph so you have the ability to really fine tune when cruising. Never thought about it until now but my buddies split gas with me on fishing trips so I just give em a total gallons used at the end of the day and everybody's happy.

steve

From: stevej Sent: 1/17/2003 7:17 PM
Forgot this the navman meter is the best value around, I love my flowscan and the analog display might be a little better to set trim with however I'm not sure that I would choose it over the navman if I were buying new because of the big price difference.

steve

From: MichaelOnTheClaraMae Sent: 1/19/2003 3:47 AM
Thanks for the information guys - sounds like the Navman is the way to go. This along with a Link 10 battery bank monitor are likely going to be "future" projects for me. I am going to have to lick my financial wounds for a while.

Michael (Clara Mae)

[Byrdman]

Interesting topic. I do not have one on my boat and feel I would/could greatly benifit. Looks like most post on this topic are a bit old with some new meter users having not yet logged many hours due to weather.. How are they working? Thanks

[Chuck S]

I have a 5gph FloScan sitting in a box on my desk right now. Just been unable to force myself to drill a 3-1/8" hole in the dash of my 16 Cruiser to mount the critter. Installation appears very straight forward, the only things to watch are the sensor has to be mounted plumb and below the engine's fuel pump. This meter shows fuel flow in gph and gallons used.

For guys with twins FloScan makes a dual needle fuel flow meter showing both engines. If mated to their dual needle tach (which has as sync function) it computes mph along with gph. This pair just replaces the twin tachs.

Anyone know of a smaller diameter tach to link to the Honda 50? There's not much room in the 16 Cruiser panel. I may have to drive down to Summit Racing and get a tach "pod" and mount this other than in the dash. Marine versions cost more than the gage!

-- Chuck

[stevej]

My flow scan is 9 years old and never had a problem. Have a good baseline on accuracy with all of the ocean trips in the lase two years. Very consistent at 5% or below error and always on the high side. The 25 is a little tougher to get a consistent fuel load in so some of the error can be attributed to that.
Like my radar I would never own a boat withot one now.

stevej

[Casey]

We had the Navman unit installed when our 2003 ("Naknek") was delivered. It has been quite useful right from the start. On our trip on the Inside Passage (earlier this summer) is was great, and proved to be quite accurate. I decided to go through the "calibration" process, and found that it was virtually on-the-money. (Over a 91.8 gallon calibration interval, the actual fill-up required 91 gallons of fuel! I guess that's close enough for my purposes!!)

I'd buy the same item again. Very happy with it. On one early occasion it did stop working (something obstructed the flow...). I disconnected the flow valve, backflushed it (I blew through it), and reinstalled. It's worked fine ever since. I do recommend that if/when you install one, that you place it so it's reasonably easy to access (mine is behind the starboard fuel tank, and pretty challenging to get to...).

Casey
...awaiting the Next Adventure!

[Sea Angel]

Happy Holidays from the Lower Ches. Bay;

I think this is a good a place as any to share my test of my NAVMAN 3100,
Fuel Management System(fuel flow) with its NEMA GPS input (it factors my 'estimated range available').

The WX was abt 67 degrees, wind SE @ abt 15kts. Chop and time kept me from getting the WOT figures.

Sea Angel has twin HONDA 90's with 15" pitch SS Props. The Spd is from my GARMIN 2006C GPS. I engaged the Autopilot to hold my heading to get the info from the instruments. The fuel tank had abt 86 gals , H2O had abt 9 gal and holding abt empty. I tried to optimize the trim for each reading.

RPM.....Spd....F/F......NM/gal
...........kts.....gal/hr

0800----3.0---0.15----20.0
1270----4.8---0.6-------8.0
1400----4.9---0.7-------7.0
2000----6.4---2.0-------3.2
2090----6.5---2.2-------2.95
2500----7.4---3.1-------2.39
3000----9.3---4.4-------2.11
3500---14.9---5.4-------2.76
4000---21.3---7.7-------2.77
4500---23.1---8.0-------2.89
5000---26.1--10.0-------2.61
WOT----??

I will try to refine these figures as the WX and Bay conditions permit.

The throttle controls (cables) have a 'bump' from just above the the idle setting to the 1800 range and is a challenge to set them in sync at times., thus the odd-ball low end RPMs.

Has anyone else run similiar numbers?

Sea Angel

[tpbrady]

Art,

I haven't done as much testing as you have, but using my Navman I was able to find comparable fuel consumption at multiple speeds on my CD22 with a 90 ETEC. At 14, 18, and 22 mph the fuel consumption was essentially the same. I used the principle of using the trim tabs to get the get the boat level port to starboard and trimming the motor up until the rooster tail just started to rise behind the motor and then looked at the speed and fuel consumption. You could have done it by just setting the throttle and then trimming the motor for best fuel economy then looking at the speed.

From your numbers it would seem to indicate the hulls perform pretty much the same.

[Sea Angel]

Tom;

Thanks for the feedback. It is encouraging.

Do you think by having the trim tabs in a neutral position first, then optimizing the speed with the motor trim for max speed would cause any different results? My thinking is abt less drag from the tabs and using just enough to balance; either way - peaking the speed for a fixed power/throttle setting. Maybe I'm saying the same as you.

I hope to find a calm day to make my runs cleaner. I did try to make a comparative run in both direction regarding the elements of current, waves & wind. The sail area of the CD25 can be a factor; especially in close quarters.

Do you have a GPS input to your NAVMAN? I assume you compared the speeds as kts verses mph. I found the NEMA hookup rather simple and reliable.

I especially like the option of the NAMAN's expected range for amount of fuel left. I am still learning the fine points of the 'toys'.

Sea Angel

[B~C]

I have hard from several sources that the Navman sending unit is only good for about 1000 gallons and then needs replaced at a cost about equal to the whole new shootin match. Anybody heard anything about this?

[journey on]

The idea of a fuel flow meter is wonderful. I noticed that all the boats that have fuel flow meters are not EFI. Honda says the 90 still has carbs. However, there is only a single line from the tank to the engine, it seems that a simple counter would not care if it was carbs or injectors.

SO THE QUESTION IS: Has anyone used a fuel flow meter on an EFI engine?

boris

[Papillon]

Art on "Sea Angel",

I was out on my boat today and was by myself, 18 gallons of fuel, 22 foot Angler model. The engine is a 1993-88hp Evinrude (4cyl-carbed)

I was looking for the best cruise speed/gallons per hour number.

I found it a 3800 RPM, 21 knots, 5.8 gallons per hour which equates 3.62 miles per gallon.

I was pleased as punch...but will check it again with the First Mate and deckhand (6lb. Papillon) on board, since this will be the norm for my boating style.

Equipment List: Navman 3100 - Garmin 188 Plotter/Sounder

[Ron on Meander]

Do you folks with the Navman Fuel Flow Meters find that the GPH fluctuates a lot even though the rpm and speed is held at a constant setting? My Yamaha fuel meter fluctuates by several gallons an hour even when I hold the speed and RPM setting constant. It never seems to settle on a GPH but moves back and forth up 33% or so. I can be running at a constant speed, for example at 4000 RPM and the fuel flow meter will read from 6 to 10 GPH and continually fluctuate in that range. So I end up using an average but I don't really believe it. I wonder if the thing is working right.
Ron

[Papillon]

Ron,
I have not noticed any fluctuation in my unit. I do find that it takes several minutes for it to catch up with my rpm when I change speeds but once it reachs the honey spot it will stay there 1/10 give or take depending on the water conditions or movement of weight on the boat, like someone moving back and forth but that is to be expected with the trim being adjusted by the movement.

[tpbrady]

Art,

I normally like to run with no trim tabs, but sometimes you can't get people to stay in one place or you don't have anything available to counteract weight lost as fuel burns off. There is a noticable improvement in fuel economy if you correct a list with trim tabs. It keeps the boat from trying to turn itself toward the direction of the lean.

I have my Lowrance connected to the Navman (after learning in a post that Navman had the cables in their installation manual reversed). I don't see the much variation in the fuel flow measurements once the boat is trimmed and left alone on flat water. However, I am not often on flat water so you see some pretty steep gyrations as the seas build. I do like the fuel remaining and range estimates. Mine is calibrated pretty well and after 50 gallons it is normally less than a .5 gallons off. You just have to remember to "refill" it when you switch tanks.

Boris, my 90 ETEC is EFI and only has a single fuel line from tank to the engine so there isn't a problem as I see it. I can't recall ever seeing a return line to the fuel tank on an outboard, but then the biggest I have ever had is a 90.

B~C, I'm halfway just about to a 1000 so I guess we will see what happens come September of next year. I will be somewhat disappointed if it decides to quit. I would expect over time to have to recalibrate it to compensate for wear. I just do know how often it would be necessary.

[Sea Angel]

B~C;
There is a recal of the system after the first 100 hrs, as per the operation manual. As to the life of the transducers, I would think if the fuel filters and mountings are correct they should last a great deal longer than 1000hrs. Yes, they are mechanical transducers that rely on clean fuel flow through the 'prop' to rotate and to create the pulse generated for the instrument. I presently lack any real knowledge as to what the mean time between failure could/should be. Hopefully the 1000hr note is not correct.

I seem to remember somewhere in my reading in the Flow Scan System inf of some life expectencies. The bearings were their focus, as I recall. Probably that is why they are so much more expensive. Come to think abt it, Flow Scan was initially my first choice till the cost for the 2 engines started to grow.

Journey On;
I have not looked into the question abt the EFI setup for FF monitoring for over a yr.,, but, I think Flow Scan did address this in their installation recommendations. Sorry, I can't find my FF transducer install manual at the moment. I seem to remember the unit had to be mounted vertically, else it could fail prematurely and be inaccurate.

Ron on Meander;
The NAVMAN has damp adjustments under the Speed and Fuel menues.

Under the Fuel menu, the 'dAmP.F' submenu allows you to select a range from 1 to 99 seconds, with 1 sec. intervals being the most sensitive. I find that 2 sec. is a nice compromize for me.

Under the Speed menu there are both an Input SENsitivity and a dAmP.S submenu. If you are using the optional paddle wheel speed transducer, this is where the SENsitivity is set; else the GPS or NO[none] input is selected. The dAmP.S has 5 settings of 6 seconds each for averaging the 'speed' traveled.

From the above there are a couple dAmP.# adjustments that could itself to fluctuations. Mechanical items, as air in the fuel line, cavation or changes in the engine's load can all cause erratic notations to the system.

I pulled some of the above from my NAVMAN Manual and some from experience. I hope this helps. Any other thoughts would be great. I am trying to extract as much info from and about my setup as possible while I do my little day trips in preparation for a possible run up the Eastern Shore this June.

Less I forget, may I wish Y'All a blessed, safe and healthy Holiday Season..

As one of those D...m Yankees who got transferred by the Navy to the 'South' and decided he liked NOT having to: [1.] shovel snow from my driveway before AND after work, [2.] remove ice from the parking brakes and [3.] mend the bruises from the falls on the ice... I stayed. Did I not also mention I can boat almost all year long....

Sea Angel