RollerCoastr
Well-Known Member
- Nov 15, 2007
- 3,884
- Boat Info
- 1997 400DA
340HP 7.4 Mercruiser Bluewaters
Garmin 741, 742, 8212, 24HD, Intellian I2
- Engines
- 1999 280BR
Twin 250HP Merc 350 Alpha Ones
This only applies to gas engines, because for reasons unknown to me, Garmin has yet to develop diesel-compatible meters (they can’t calculate returned fuel – so they’re not compatible with gas-return system either).
I've never subscribed to the "it feels right at xxxx rpm..." method of determining optimal cruise speed, so I spent several years of keeping logs and experimenting with cruising speeds and trim to determine the best strategy for my 1997, 340 HP 400DA. That provided me with some respectable data, but really only a long-term average. I wanted a way to measure variables (load etc) and track issues such as uneven fuel burn.
Before the introduction of the GFS-10 product, I looked into Floscan, but they seemed expensive at the time and I wasn't wild about changing out the tachs or redesigning the instrument panel. The GFS-10's tight integration into existing plotting equipment and displays piqued my interest several years ago, but I didn't take the plunge until over 10 years into my ownership experience.
I did a lot of research before placing my order with BOE Marine, but I still had some misconceptions about the operation and installation. Quite honestly, I didn't find the installation as simple as many forum posts lead me to believe. I assumed that each sensor had a single, long NMEA-2000 drop cable that I would simply run to the existing Garmin micro NMEA-2000 T-bus at the dash. Had I looked closer, I'd have seen that such is not the case. Each sensor has a regular NM2K drop cable, AND a loooong signal/power cable for power, ignition, fuel gauge, CAN-et and ground.
That meant that I had to buy a long backbone cable, build a T-bus in the ER, and find a way to connect bare leads to my accessory and ignition switches at the dash. ugh
I opted against connecting the fuel gauge leads, and thus far I haven't regretted it. The only reason I can think of to do that is to possibly monitor fuel draws from the generator, because that cannot be otherwise metered. Even if the genny shared a fuel line or if I was willing to purchase a 3rd meter for it, each GFS-10 can only reliably measure flow rates at 2 GPH or more. The fuel gauge effort would also have to assume that:
- I was willing to perform many calibrations of the sender by manually measuring tank level and entering that data
- the generator consumption was significant
- I had faith in the reliability of the sender in the first place.
Since none of those conditions apply, I snipped those leads. There is a downside: Garmin currently offers no way to track remaining fuel per tank (only total fuel onboard). The only option available as of this writing is to connect the GFS-10's to the fuel senders, and manually calibrate them.
The sensor installation held no surprises, but I had to compromise. Garmin suggests that the sensors be installed:
- above the top level of the fuel tanks (presumably to avoid a siphon in the event of a leak)
- positioned for an upward-flow (to allow air bubbles to pass through)
- upstream of fuel manifold/tank selector valves (to avoid the introduction of air)
As is common in many cruisers, the top of my fuel tanks are more or less at the top of the ER, so I could only manage two out of three. The clear choice for me was upward and upstream. I chose to omit Garmin's inline filter, as I have spin-on water/fuel separating filters upstream and downstream of each sensor. I also read several posts about the Garmin filters restricting flow, so I'm not sure I would install them even in a single-filter setup.
Even with above compromise, the method and location of the desired position on the firewall bulkhead meant that I needed to replace one of the hoses on fuel manifold with a longer one. I enlisted the help of my mechanic for that. He knew exactly how and where to get a custom hose and he had me hooked up in less than 2 hours.
Garmin provides very clear best-practice documentation for NM2k network configurations, but even so, I was confused by the power requirements. My existing network was already equipped with their power-injecting adapter, and the docs state that each network can only support ONE of them, yet each GFS includes a power lead.
The purchasing specs claim that an SD card containing software updates is included. It's not. That wasn't a problem for me because I keep up with updates anyway, but I was disappointed to not get a couple of free SD cards - you can never have too many...
With everything hooked up and powered on, my GPSMap 5212, at the time running ver. 6.5, automatically saw the sensors on the network, and it let me label and configure them. Very cool. I customized as much as I could, identifying each sensor, labeling it, labeling the tanks and entering the capacity of each tank. (which are unique to each side on the 400DA) After playing around with the customization, I realized that not only did the 5212 think that I had installed a 3rd engine, but I also lost the data input from the port sensor. Oops. A quick reset to default on the port sensor and more careful configuration rectified that.
The info can be shown full-screen, split screen, in a data bar at the bottom of the chart/radar screen, or on a separate compatible Garmin display, such as the GMI-10 or the newer GMI-20.
I had to get accustomed to a delay in the data. My heart skipped several beats the first time I got on plane, trimmed out and looked down at the mpg reading. I hadn’t realized that it wasn't instant. I even changed screens so my guests wouldn't see it! After some investigation, I discovered that the fuel data is calculated very quickly - within less of a second in change in flow, but the speed data from the GPS lags.
My last issue is another that seems fixable to me - particularly in light of Garmin's historical commitment to software fixes. The mpg readout only gives data to the tenth place, which results in way too much rounding, IMO. I have submitted a feature request for an additional decimal place to be added to the mpg readout. Garmin Tech Support said they would pass that along to engineering for consideration.
Overall, I think they're great. If I have any regrets, it's not installing them sooner.
I've never subscribed to the "it feels right at xxxx rpm..." method of determining optimal cruise speed, so I spent several years of keeping logs and experimenting with cruising speeds and trim to determine the best strategy for my 1997, 340 HP 400DA. That provided me with some respectable data, but really only a long-term average. I wanted a way to measure variables (load etc) and track issues such as uneven fuel burn.
Before the introduction of the GFS-10 product, I looked into Floscan, but they seemed expensive at the time and I wasn't wild about changing out the tachs or redesigning the instrument panel. The GFS-10's tight integration into existing plotting equipment and displays piqued my interest several years ago, but I didn't take the plunge until over 10 years into my ownership experience.
I did a lot of research before placing my order with BOE Marine, but I still had some misconceptions about the operation and installation. Quite honestly, I didn't find the installation as simple as many forum posts lead me to believe. I assumed that each sensor had a single, long NMEA-2000 drop cable that I would simply run to the existing Garmin micro NMEA-2000 T-bus at the dash. Had I looked closer, I'd have seen that such is not the case. Each sensor has a regular NM2K drop cable, AND a loooong signal/power cable for power, ignition, fuel gauge, CAN-et and ground.
That meant that I had to buy a long backbone cable, build a T-bus in the ER, and find a way to connect bare leads to my accessory and ignition switches at the dash. ugh
I opted against connecting the fuel gauge leads, and thus far I haven't regretted it. The only reason I can think of to do that is to possibly monitor fuel draws from the generator, because that cannot be otherwise metered. Even if the genny shared a fuel line or if I was willing to purchase a 3rd meter for it, each GFS-10 can only reliably measure flow rates at 2 GPH or more. The fuel gauge effort would also have to assume that:
- I was willing to perform many calibrations of the sender by manually measuring tank level and entering that data
- the generator consumption was significant
- I had faith in the reliability of the sender in the first place.
Since none of those conditions apply, I snipped those leads. There is a downside: Garmin currently offers no way to track remaining fuel per tank (only total fuel onboard). The only option available as of this writing is to connect the GFS-10's to the fuel senders, and manually calibrate them.
The sensor installation held no surprises, but I had to compromise. Garmin suggests that the sensors be installed:
- above the top level of the fuel tanks (presumably to avoid a siphon in the event of a leak)
- positioned for an upward-flow (to allow air bubbles to pass through)
- upstream of fuel manifold/tank selector valves (to avoid the introduction of air)
As is common in many cruisers, the top of my fuel tanks are more or less at the top of the ER, so I could only manage two out of three. The clear choice for me was upward and upstream. I chose to omit Garmin's inline filter, as I have spin-on water/fuel separating filters upstream and downstream of each sensor. I also read several posts about the Garmin filters restricting flow, so I'm not sure I would install them even in a single-filter setup.
Even with above compromise, the method and location of the desired position on the firewall bulkhead meant that I needed to replace one of the hoses on fuel manifold with a longer one. I enlisted the help of my mechanic for that. He knew exactly how and where to get a custom hose and he had me hooked up in less than 2 hours.
Garmin provides very clear best-practice documentation for NM2k network configurations, but even so, I was confused by the power requirements. My existing network was already equipped with their power-injecting adapter, and the docs state that each network can only support ONE of them, yet each GFS includes a power lead.
The purchasing specs claim that an SD card containing software updates is included. It's not. That wasn't a problem for me because I keep up with updates anyway, but I was disappointed to not get a couple of free SD cards - you can never have too many...
With everything hooked up and powered on, my GPSMap 5212, at the time running ver. 6.5, automatically saw the sensors on the network, and it let me label and configure them. Very cool. I customized as much as I could, identifying each sensor, labeling it, labeling the tanks and entering the capacity of each tank. (which are unique to each side on the 400DA) After playing around with the customization, I realized that not only did the 5212 think that I had installed a 3rd engine, but I also lost the data input from the port sensor. Oops. A quick reset to default on the port sensor and more careful configuration rectified that.
The info can be shown full-screen, split screen, in a data bar at the bottom of the chart/radar screen, or on a separate compatible Garmin display, such as the GMI-10 or the newer GMI-20.
I had to get accustomed to a delay in the data. My heart skipped several beats the first time I got on plane, trimmed out and looked down at the mpg reading. I hadn’t realized that it wasn't instant. I even changed screens so my guests wouldn't see it! After some investigation, I discovered that the fuel data is calculated very quickly - within less of a second in change in flow, but the speed data from the GPS lags.
My last issue is another that seems fixable to me - particularly in light of Garmin's historical commitment to software fixes. The mpg readout only gives data to the tenth place, which results in way too much rounding, IMO. I have submitted a feature request for an additional decimal place to be added to the mpg readout. Garmin Tech Support said they would pass that along to engineering for consideration.
Overall, I think they're great. If I have any regrets, it's not installing them sooner.
Last edited:
