posted 07-07-2005 08:31 AM ET (US)        

The principal attraction of the NAVMAN 3100 is its ability to accept a SPEED input, either from a Navman paddlewheel sensor or from a NMEA connection (such as from a GPS receiver). With a speed input, the device will compute instantaneous fuel consumption rates in MILES PER GALLON (or other units).

The device also tracks the amount of fuel used. It provides a continuous tank level indication (a thermometer-style vertical bar graph). You can also select display of gallons remaining in the tank. Total fuel use is also recorded and displayed.

In addition, the device also tracks engine hours. It also displays battery voltage.

I was very pleased with the device. Once I became acquainted with the controls and menus, it was very simple to operate the device and to select the information I wanted to display. The size of the display and the front panel buttons are appropriate. It is easy to see, and the buttons are large enough and far enough apart that operating them is easy even in a small boat underway at speed.

When I purchased the Navman 3100 I did so in preference to two other choices:

--Navman 2100
--Navman SONAR or GPS with fuel transducer option

The principal difference between the NAVMAN 2100 and NAVMAN 3100 models is the ability to accept a SPEED input and compute fuel economy. I found this very useful.

The principal difference between the 3100 and a SONAR or GPS with the fuel transducer option is the separate display device. I found this preferable to switching the display on the SONAR to another page.

posted 07-07-2005 02:44 PM ET (US)            

did you calibrate the fuel sensor as advised in the Op Manual ?

posted 07-08-2005 07:17 AM ET (US)            

In order to adjust the calibration from the factory setting it is necessary to have an alternative method of measuring fuel flow with a degree of accuracy which is believed to be greater than the the existing calibration. At the moment I do not have such an alternative method available which I believe would be more accurate than the existing.

The simplest approach to measuring fuel flow would be to defer to the calibration of the fuel flow transducer on another pump, for example, on the pump dispensing gasoline at the point of sale.

One would fill the vessel's fuel tank to a particular level, run the engine for sufficient time to consume a reasonable quantity of fuel, perhaps 5 gallons, then refill the tank to the initial level. Measurement of fuel flow would then be deduced by comparing the indicated amount of fuel used on both gauges, relying on the fuel flow transducer in the gas pump dispensing the fuel as the standard.

The accuracy would be limited by:

--the precision to which the tank was re-filled to the same level
--the precision of the fuel flow transducer on the dispensing pump

The fuel system on my boat does not have provisions for connecting an alternative tank, so the main 77-gallon tank would have to be used. I do not believe that I can re-fill the 77-gallon tank to the same level with a great deal of accuracy, unless I were to fill the tank so that the fuel level rose above the tank top and into the filler hose. At that level of fill you could observe the fuel level visually and re-fill to the same level.

I am reluctant to fill the main tank above the top of the tank for many reasons, including to avoid having fuel sit in the filler hose which is composed of 13-year-old rubber for long periods of time.

In order to minimize small errors in measurement in the refilling of the tank to the same level in the calibration process, the more fuel used in the calibration run the better.

After measuring the flow of over 200 gallons of fuel, it appears to me the factory setting is accurate enough for my purposes at the moment. If there were an error of 10-percent, I would have seen a variance of 20-gallons at this point, but I do not see any difference between apparent consumption and measured consumption of that magnitude. If there is an error, it appears to tend to slightly overstate fuel flow rate. An error in that direction is preferable to an error which understated fuel flow rate. (That could lead to running out of gas.)

posted 07-08-2005 08:43 AM ET (US)            

--brewing up small batches of treated fuel for winterization or cleaning of the engine;

--carrying extra fuel in on-deck tanks on long trips.

posted 07-11-2005 12:07 PM ET (US)            

The fuel 3100 is accurate to within 5% out of the box and within 1-2% after calibration. The reason for the suggestion to use a 6 gallon fuel tank is accuracy of a know amount of fuel used. You can use the fuel tank in the boat as long as you have an accurate method to measure the actual fuel used.

posted 12-28-2005 01:45 AM ET (US)            

I'm still waiting for e-mail tech support from Garmin and Navman.

posted 12-28-2005 02:30 AM ET (US)            

First, you have to find an OUTPUT from the GPS and an INPUT on the NAVMAN. These have to be connected with due care for the polarity and grounding.

Next, you have to configure the GPS to send the right NMEA SENTENCE. This may be the sticking point. Buried in the NAVMAN technical appendix is a list of sentences which can be used. Buried somewhere in the GPS should be a menu where you can select the sentences to be transmitted.

Finally, you have to configure the NAVMAN to use the GPS input.

posted 12-28-2005 07:47 AM ET (US)            

4800 bps is the most common speed.

posted 12-29-2005 03:46 PM ET (US)            

Seasonal Data 2005
-------------------
Gallons used = 508.7 gallons
Total log = 941.3 miles
Total hours = 67.3 hours

posted 12-29-2005 05:53 PM ET (US)            

I would think that Navman could afford a proof reader for thier installation manual. Now, if Lowrance is correct in yellow being transmit, I will be comunicating. John

posted 12-29-2005 06:10 PM ET (US)            

1. There is no standardization of NMEA color codes across
different manufacturers. Even Garmin uses different colors
on different units.

2. NMEA out on the Garmin 60C is BROWN, not white, according
to the 60C manual.

So GPS Brown to Navman Yellow. Best to follow the physical
root the ground connectors follow.

posted 12-29-2005 09:45 PM ET (US)            

http://www.navman.com

Page 17 shows the details of the NMEA wiring. You connect your GPS output to the NAVMAN input. The YELLOW wire on the pigtail from the Navman is the input signal; the black wire is the signal reference or common or battery negative. This is also confirmed on Page 19 in the table.

Page 17 also mentions the NMEA data required from the GPS: it wants a sentence with the data RMC. This is again repeated in the table on Page 19.

To connect your GPS to the NAVMAN:

--wire an NMEA-0183 output from the GPS to the yellow wire input. The NAVMAN has single-ended or unbalanced inputs. If the GPS has balanced or differential outputs (which will be labeled + and -), just connect the (+) wire to the NAVMAN's yellow input. Connect the common/ground/battery negative of both the GPS and the NAVMAN to the battery negative bus. If the GPS has differential outputs, do not connect the (-) lead of the differential output to ground. Follow these instructions no matter what someone else tells you! Never connect a differential output to ground!

--configure your GPS to transmit the NMEA sentence RMC on its output. Refer to the manual for your particular GPS. Generally you can select what data will be sent on a particular output. In my case my GPS has multiple outputs. I use one for the NAVMAN and a second one to transmit to my DSC radio.

posted 12-29-2005 10:53 PM ET (US)            

I tested the Navman today and still have no communication between the GPS and the Navman. I will read through the info you posted after dinner. My manual is on my boat in the water.

I currently have the NMEA output from mt GPS (brown)connected to my yellow NMEA input oo the Navman. I also have the NMEA ground on the Navman joined with the common ground from the GPS connected to the battery negative.

posted 12-30-2005 12:43 AM ET (US)            

Upon furhter reading of both online manuals I have found out that my new Garmin 60c GPS supports NMEA 0183 version 3.01 and my new Navman 3100 fuel accepts NMEA 0183 version 2. I wonder if this is where the problem lies

Since they are both new and support NMEA 0183, I assumed they would be compatible. I will be very dissapointed if they are not because together, they were quite expensive.

posted 12-30-2005 09:38 AM ET (US)            

The Navman 3100 uses NMEA 0183's "RMC" (Recommended minimum specific GPS/Transit data) sentence to acquire speed information from the GPS. Almost any GPS made in the last 10 years, including the Garmin 182C and 60C, has this basic sentence in its "vocabulary". Thus, I doubt that the fact that the Navman and the Garmin use different versions of NMEA 0183 is the cause of any communication problems.

posted 12-30-2005 09:55 AM ET (US)            

What firmware level in the GPS? Latest is 4.00, from June.

And I agree with Peter, the NMEA level isn't the problem.
The only problems I've heard about with NMEA level have
been when the receiving unit (in the case the Navman) wanted
a higher level than the transmitter (GPS) was sending.

posted 12-30-2005 10:46 AM ET (US)            

Will I be able to test this thing inside a metal pole barn?
I doubt it, maybe the Navman screen for mpg will look differnt.

In case Navman is monitoring this thread,

(I am typing this in my most sarcastic "voice".)

So, your manuals for 2003 and 2004 are incorrect.

Who is putting these things together, the owner's wife?

Jeepers creepers guys, there is only 23 pages of instructions on mounting and installing a 3100. The only reason I bought this more expensive unit was for the GPS hookup. Is everybody else using the paddle wheel?

posted 12-30-2005 11:43 AM ET (US)            

Chuck, so you tell me my GPS does not have differential outputs; does this mean I just connect the NMEA "OUT" wire from the GPS to the NMEA "IN" wire on the Navman or do I also join the ground wires together and connect them to a common ground from the battery?

posted 12-30-2005 08:34 PM ET (US)            

I then took my backup Garmin eTrex on the boat and jerry rigged it with wires to the Navman and voila, I had speed displayed on the Navman unit. I was relieved I was able to determine the problem was the GPS but dissapointed that I have to wait for it to be repaired.

Thanks all for your help and have a Happy New Year!

posted 12-31-2005 01:26 AM ET (US)            

The ground wires have to be ultimately connected together back
at the battery, though, its best if the ground and NMEA wires
travel approximately the same path to reduce noise on the
NMEA connection.

posted 01-07-2006 08:15 AM ET (US)            

All of this has no bearing on how the Navman 3100 operates because each motor has its own fuel flow sender between the fuel filter and the motor monitoring fuel flowing to it. The fuel flow senders are connected together via a Navman supplied T-connector and the T-connector plugs into the sender input wire to the Navman 3100.

posted 11-19-2006 09:19 AM ET (US)            

I am still very happy with the NAVMAN 3100 FUEL instrument. This season I found a new use for it: a engine diagnostic tool.

posted 09-15-2007 11:13 AM ET (US)            

--Gallons
--Miles
--Hours

By logging this data you can compute the following averages:

--Miles per gallon
--Miles per hour
--Gallons per hour

Without the NAVMAN as my recording secretary I would never have collected this information. As a result I can now track several interesting trends with my boat and motor. Here is a summary:

Seasonal Data 2005
-----------------
Gallons used = 508.7 gallons
Total log = 941.3 miles
Total hours = 67.3 hours
Average fuel economy = 1.85 MPG
Average speed = 14.0 MPH
Average fuel flow = 7.55 GPH

Seasonal Data 2006
-----------------
Gallons used = 521.3 gallons
Total log = 908.7 miles
Total hours = 60.5 hours
Average fue economy = 1.74 MPG
Average speed = 15.0 MPH
Average fuel flow = 8.61 GPH
Seasonal Data 2005 and 2006
-----------------
Gallons used = 1030.0 gallons
Total log = 1850 miles
Total hours = 127.8 hours
Average fuel economy = 1.80 MPG
Average speed = 14.5 MPH
Average fuel flow = 8.06 GPH

posted 02-07-2008 10:48 PM ET (US)            

Seasonal Data 2007
-----------------
Gallons used = 359 gallons
Total log = 609.9 miles
Total hours = 60.9 hours
Average fue economy = 1.70 MPG
Average speed = 10.0 MPH
Average fuel flow = 5.9 GPH
Seasonal Data 2005 thru 2007
-----------------
Gallons used = 1389 gallons
Total log = 2459.9 miles
Total hours = 188.7 hours
Average fuel economy = 1.77 MPG
Average speed = 13.0 MPH
Average fuel flow = 7.36 GPH

It appears that since NAVMAN has been sold to NAVICO, the NAVMAN brand has been melded into the NORTHSTAR line. However, it appears that the 3100 FUEL INSTRUMENT has been dropped from the catalogue. One reason for this may be due to a conflict with another fuel flow measuring and computing device, the LOWRANCE LMF 400. As it happens, the parent company, NAVICO, also owns LOWRANCE. Since LOWRANCE has their own fuel computer instrument, the 3100 may have been the odd man out in this corporate game of musical chairs.

posted 03-20-2008 12:47 AM ET (US)            

Since Northsar (NAVACO) purchased Navman here in the U.S. I wonder if they will market the 3100s and stick the Northstar name on it? I hope so, because I really think this is a cool device.

posted 07-20-2008 11:31 AM ET (US)            

Is it possible to change tanks with a fuel flow valve? If so, you ought to run on the main tank, and then switch to the 6-gallon while running. If the tank is truly the cause of the ten-fold change in the 3100 FUEL instrument's reading, it should show up immediately as you change tanks.

The only mechanism I can imagine by which the tank could affect the fuel flow transducer reading is through a change in fuel hose vacuum pressure. It may be that the fuel system suction is significantly different between the two tanks, and that this difference in vacuum pressure affects the transducer.