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Author Topic:   NAVMAN Fuel 3100
jimh posted 07-24-2004 11:05 PM ET (US)   Profile for jimh   Send Email to jimh  
The NAVMAN Fuel 3100 fuel flow meter appears to be a good unit. I would be interested to hear comments from owners.
Peter posted 07-25-2004 09:16 AM ET (US)     Profile for Peter  Send Email to Peter     
I have one of these rigged to measure flow through both engines. It gets two thumbs up.

It has an upper and lower numeric display. The upper display will provide information relating to fuel consumption and the lower display will display speed and distance information depending on user selection.

When connected to the NMEA output from a GPS, it will compute fuel economy and display that on the upper display. Also, when connected to the NMEA output from a GPS, the lower display will display a computed range based on the calculated level of fuel in the tank. It will display the rate of consumption in GPH for each of the engines (upper and lower displays used) or the combined rate.

It also provides a bar graph fuel tank gauge which gives a tank level indication based on consumption for up to two tanks. The user must indicate the capacity of the tank(s) as well as the number of gallons in the tank(s). Usually, this function is reset by the user everytime the tank is filled. Because I have three tanks on my 27 Whaler, I have configured the fuel gauge as a single gauge to give a measure of total remaining fuel.

The LCD digits are large and easy to read when installed at a reasonable viewing distance such as in the dashboard as I have it. It was as easy to install as any other gauge, but one of the hardest installation tasks was finding a place to put it on my dashboard. The display is almost square in shape and takes up about 5 square inches of real estate. The square shape is a "sailor's style" gauge. The transducer should be installed after the fuel/water separator and must be installed so as to be vertically oriented. This may be a bit tricky on an Outrage/Revenge where there is not much freeboard. It wasn't a problem on the 27 as it has a traditional bilge.

I use mine primarily configured to show MPG on the top display and speed on the bottom display. This configuration allows me to adjust the boat for the most fuel efficient performance for the conditions.

Overall, this is an excellent product and is reasonably priced compared to its competition. I belive it can be had for under $300 if one shops around.

jimh posted 07-25-2004 09:56 AM ET (US)     Profile for jimh  Send Email to jimh     

Thanks for that very cogent reply. I do like the concept that the gauge is able to instantaneously compute fuel economy and display it. I do not believe other manufacturer's have this ability in a similarly priced gauge.

The only drawback I see it the square mounting shape. All of the other instruments in my gauge cluster are round.

Backlash posted 07-25-2004 11:26 AM ET (US)     Profile for Backlash  Send Email to Backlash     

Another consideration is the Navman 2100 for about $150. It is round and mounts in a 2" round hole. It is designed for single engine installation only. I have the exact same unit in the Standard Horizon brand. I use mine primarily to indicate how much fuel I have remaining in my tank and it works great...down to 1/10th of a gallon.

Features - Navman 2100
Instant fuel flow: 5 to 130 litres/hour, 1.4 to 35 US gallons per hour, or 1.1 to 30 imperial gallons per hour.
Suitable for carbureted 2- stroke engines from 50-300hp carbureted 4-stroke engines from 90- 300hp. Minimum flow rate 5 litres (1.3 US gallons) per hour.
Trip and total fuel consumption, user resettable, up to 999 units.
Designed for single engine applications only.
Volume remaining in tank (provided that the total tank volume has been entered).
Alarms: Low fuel alarm.

As Peter mentions, the fuel flow sensor must be mounted vertically to operate properly. This is easily accomplished by looping the fuel line.


jimh posted 07-25-2004 01:35 PM ET (US)     Profile for jimh  Send Email to jimh     

That is a great photo album! My favorite is number 13 that shows you instrument panel. Your installation is the standard to judge by--what a great looking set up!

Backlash posted 07-26-2004 04:05 PM ET (US)     Profile for Backlash  Send Email to Backlash     

Thanks! The 21' Walkaround has a huge electronics panel and no dash so all electronics must be flush mounted.


LHG posted 07-26-2004 04:10 PM ET (US)     Profile for LHG    
I think the Navman fuel flow meter technology is the same as the Mercury Smart Craft, or visa-versa.
Legobusier posted 07-26-2004 04:22 PM ET (US)     Profile for Legobusier  Send Email to Legobusier     
Steve, that's one nice looking, clean boat. Most impressive.


jimh posted 07-26-2004 08:21 PM ET (US)     Profile for jimh  Send Email to jimh     
Actually, as far as I can tell there is no relationship between the NAVMAN and the SmartCraft instruments.

The NAVMAN uses a flow sensor that is external to the engine and measures actual fuel flow by in-line attachment to the fuel hose. It is applicable to any engine.

The SmartCraft gauge relies on the engine's control module to deduce the fuel flow based on how much time the fuel injectors are open. Since the amount of fuel used is directly porportional to the fuel injector use, the SmartCraft computer just deduces the fuel flow from this data indirectly. It figures each time an injector is operated a known about of fuel is squirted into the engine. By keeping track of this it totals up the fuel usage.

It would be redundant to have both a SmartCraft gauge system and a NAVMAN (or other brand) external fuel flow sensor, but I do not believe there is anything common in their technology. They are birds of a different feather.

Joe Kriz posted 07-26-2004 08:34 PM ET (US)     Profile for Joe Kriz  Send Email to Joe Kriz     
I have not seen any links to the NAVMAN here.

Are there any links?
Any particular models prefered?

Backlash posted 07-26-2004 10:11 PM ET (US)     Profile for Backlash  Send Email to Backlash     

Here's a link to the Navman Marine site showing their fuel flow gauges:

The 3100 is what jimh was originally talking about and is a new model. Several members here have the 2100 or the Standard Horizon FF41 (I believe) which is identical. They are available for around $150. Don't know if Navman makes the unit for Standard or vice versa.

Chris, thanks for the kind words.


Peter posted 07-26-2004 10:14 PM ET (US)     Profile for Peter  Send Email to Peter     
Navman 3100 can be seen here . I don't see a link for the 2100 and wonder if it has been discontinued. The 2100 fuel flow meter doesn't have the economy computer.

Peter posted 07-26-2004 10:17 PM ET (US)     Profile for Peter  Send Email to Peter     
Nevermind, Steve found it.
dittybag54 posted 07-26-2004 11:42 PM ET (US)     Profile for dittybag54  Send Email to dittybag54     
Interestingly enough, Brunswick has now bought the 30% of Navman that they did not already own. The operation is staying in New Zealand with everything intact but this will give Mercury a huge inroad into GPS and Combined systems that Navman has. I keep wondering if it would be possible to cheat with the 2100 and use it with a Mercury classic 40. They claim it must be a minimum of 50 H.P. outboard but that seems like it could be played with a bit. I would love to not have to bend down and look under the seat to see how fuel is going in that portable tank. Am wondering if it relates to pressure or a minimum flow the sender must have to work. May look into this.
bw12 posted 07-27-2004 01:08 AM ET (US)     Profile for bw12    
Since the 2100 model has a minimum 50 hp two-stroke and 90 hp four-stroke rating, I assume the 3100 would have the same limitation also even if it does not say so. I doubt they would use different flow sensors. Kind of make these instruments useless for the smaller engines.
Joe Kriz posted 07-27-2004 01:37 AM ET (US)     Profile for Joe Kriz  Send Email to Joe Kriz     
Steve & Peter,

Thanks for the Links.

As jimh mentions, the square shape is different then most other 2" style gauges and the cost of the 3100 is $350 at BoatersWorld as compared to $150 for the 2100.

Either one looks like a great instrument to have for calculating fuel usage, and optimizing fuel conservation, over long trips.

Great looking boat Steve. Am I correct in (barely) seeing the Navman 2100 in the lower left of the instrument panel in photo #13?

Backlash posted 07-27-2004 08:52 AM ET (US)     Profile for Backlash  Send Email to Backlash     

Thanks, the helm photo was taken prior to installing the Standard FF41. It is installed in the space previously occupied by the trim tab switch in lower right corner of the photo.

Prior to the introduction of the Navman and Standard Horizon fuel flow gauges, your only option was the very nice $300+ FloScan gauge. Yamaha also has a beautiful gauge that matches their twin digital gauges at $500-$600!

My main reason for installing the fuel flow gauge was to get an accurate reading of how much fuel I had remaining in the tank. The low fuel light on my Yamaha bar graph fuel gauge starts flashing when there is still 30 gals. remaining in the tank! The Standard FF41 solves this problem very nicely. It also shows gallons burned per hour so you can select the most economical cruising speed. The gauge can also be fine tuned for even greater accuracy.

This spring I fired up the outboard, on ear muffs, to burn off the fogging oil and let it idle for about 5 minutes. The gauge showed I used 2/10 of a gallon during this period.

BTW, the fuel flow sensor contains a tiny impeller (turbine?) which computes the fuel flow.


Plotman posted 07-27-2004 10:22 AM ET (US)     Profile for Plotman  Send Email to Plotman     
Steve - why wouldn't the 2100 work for a dual engine installation as long as the total fuel consumption is less than the 300hp total and the sensor is placed before the fuel line splits to feed the separate engines?

Great pictures!


Plotman posted 07-27-2004 10:22 AM ET (US)     Profile for Plotman  Send Email to Plotman     
Steve - why wouldn't the 2100 work for a dual engine installation as long as the total fuel consumption is less than the 300hp total and the sensor is placed before the fuel line splits to feed the separate engines?

Great pictures!


Plotman posted 07-27-2004 10:43 AM ET (US)     Profile for Plotman  Send Email to Plotman     
Also very interesting to see that if you have one of their chartplotters or fishfinders, you can buy the fuel flow sensor and add the functionality to those instruments.
andygere posted 07-27-2004 11:18 AM ET (US)     Profile for andygere  Send Email to andygere     
I also have the Standard Horizon FF41 (same as Navman 2100) and I agree that it is a great instrument. It tracks very closely with the in-floor mechanical guage on my Outrage 22, and really helps me to dial in the most efficient cruising speed. It also gives me a lot of confidence when taking longer trips. When I purchased it about a year ago, there was a factory rebate program that dropped the net cost to less than $100.

Plotman, the instrument sending unit needs to be installed downstream of the fuel filter, as close to the fuel pump as possible, so a split on the FF41/2100 is not practical for twin set-ups using smaller outboards. At least this is what I deduced from the instructions. My first idea was to do just what you suggest with my main engine and my kicker, but I followed the manufacturer's instructions and only installed it on the main engine fuel line. The kicker uses such a small amount of fuel, even several hours of trolling does not cause much of an error in the fuel totalizer function.

where2 posted 07-27-2004 01:10 PM ET (US)     Profile for where2  Send Email to where2     
The Standard Horizon FF41 is made by Navman. I blatantly asked the Navman reps at the Miami International Boat show 2 years ago... They said "We make Standard Horizon's gauge for them, or you can buy ours for less $$$. The choice is yours..."
Backlash posted 07-27-2004 01:20 PM ET (US)     Profile for Backlash  Send Email to Backlash     

I really don't see why you couldn't hook up a 2100 to twin engines as long as the maximum flow didn't exceed the 35 gallons per hour limit of the unit. Obviously the fuel flow sensor wouldn't know if you had a single 300 HP outboard or twin 150's.

If you installed two 2100's (one for each engine) you would be able to monitor each engine's performance, economy, etc., but the remaing fuel in tank would not be easily determined. The 3100 is really designed for twin installations.


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