Recently, I commissioned a custom-built aluminum fuel tank for my 22-foot center-console fishing boat. In ordering the new tank, I asked the fabricator to forgo the traditional hole on top for mounting a fuel-gauge sending unit.
Why?
Because my boat doesn’t have a fuel gauge, at least not the conventional type. I tossed this once-ubiquitous marine gauge nearly 10 years ago. My reasoning was threefold. For one, traditional marine fuel gauges are notoriously inaccurate. With fuel sloshing around inside the tank, the float on the sending unit bobs about like a cork in a tempest-lashed ocean, sending the needle on the fuel gauge swinging to and fro, rendering the instrument almost useless.
Second, mounting a sending unit means creating a hole in the fuel tank—and any hole will eventually leak, my experience has shown. Third, and most importantly, my outboard features NMEA 2000 (N2K) digital connectivity that shows fuel burn rates (in gallons per hour) on one or more engine displays, and that brings us to the point of this story.
Original Equipment Systems
Today, electronic fuel-management systems are available from every major outboard brand for motors ranging from midsize to large. Fuel data from the engine’s digital brain is transmitted to a display at the helm, keeping skippers apprised of the fuel consumption rate at any given time, as well as the total fuel consumed. This data proves very accurate—within a few tenths of a gallon, as I’ve discovered in more than a decade of using these systems.
The data is immensely useful to boating anglers, not only in striving for the most efficient cruising speed and the greatest range in changing sea conditions, but also in determining how much fuel remains in the tank. You don’t have to do the math in your head (i.e., subtracting the amount of fuel burned from the amount of gas in the tank when you left port). Today’s fuel-management systems for marine engines can be set up to continuously calculate the remaining fuel and show it on the engine display or an N2K-connected MFD. The same technology will also continuously inform you of miles per gallon, allowing you to adjust speed, trim and other parameters to maximize fuel economy.
If you find yourself on the verge of buying a saltwater fishing boat, do yourself a big favor and make sure the propulsion system can output digital data to an engine display that includes a fuel-management function. With Yamaha outboard power, for example, this will be an instrument like the Yamaha Command Link round speedometer/fuel meter or the CL7 7-inch touchscreen display.
With Suzuki outboards, this might be one of many choices, including the SMG4 4-inch display or the SMD7 7-inch touchscreen display. As mentioned earlier, you can also call up fuel data through N2K connections on compatible MFDs from brands such as Furuno, Garmin, Lowrance, Simrad and Humminbird.
Aftermarket Systems
Yet, what if you have an older engine, one without an advanced digital data output for fuel consumption? Are you stuck with an old, inaccurate fuel gauge? Thankfully, the answer is no. There are a number of aftermarket systems that measure fuel flow and totalize the gallons of fuel consumed. Most do so by teeing into the fuel line and displaying data on a multifunction display or a separate monitor via N2K connections. Here are just a few examples of today’s high-tech solutions for old-tech boats and motors.
Garmin’s GFS 10 compact fuel sensor adds fuel monitoring to your Garmin MFD. The flow sensor tracks fuel use and transmits the data via the Garmin CANet or N2K. Maximum fuel-flow rate for the GFS 10 is 50 gph, and the minimum flow rate is 2 gph. $165.95; thegpsstore.com.
Lowrance’s EP-60R electronic fuel-flow sensor tracks gallons per hour and fuel used, as well as fuel economy when networked with GPS. The compact sensor uses an internal paddle wheel to measure fuel flow and includes a 10-foot cable, an N2K T-connector and two 1-inch hose clamps for teeing the sensor into the fuel line. It shares the information on a compatible Lowrance display with N2K connectivity. $219; amazon.com.
Maretron’s FFM100 sensor is designed to use positive displacement metering technology to precisely measure fuel flow and then convert and transmit that data via N2K to an MFD. Measuring 3.5-by-4.2-by-2.03 inches, the FFM100 system can be used for both gasoline and diesel marine engines. $327.05; hodgesmarine.com.
US Marine Products’ USMP-10 kit includes a compact fuel-flow meter for gasoline or diesel, a 25-foot cable with a plug, and a 213/16-inch-by-23/16-inch stand-alone display. It automatically monitors gallons per hour and tracks total fuel consumed. Designed for a 3/8-inch ID fuel hose, the kits include two hose clamps. Maximum fuel-flow rate for the USMP-10 is 78 gph, and the minimum flow rate is 15.8 gph. $199; usmarineproducts.com.
Airmar Technology’s SmartFlex dual-chamber diesel fuel-flow meter is designed for diesel engine systems with flow rates up to 158.5 gph. It measures fuel consumption in each line and computes the difference between supply and return inherent to marine diesel fuel systems. The meter uses N2K to connect with an Airmar T1 or T2 SmartBoat or SmartFlex module to display fuel data on an MFD. $506.74 (excluding the SmartBoat or SmartFlex module); wmjmarine.com.
Read Next: How Much Fuel Capacity Do I Really Need?
SeaGauge’s AGW Fuel-Flow Kit provides fuel flow and a variety of other digital data for diesel engines and connects via N2K to show fuel information on compatible displays. Housed in a solid ABS plastic watertight box (measuring 5.5 inches long by 1.47 inches tall by 4.7 inches wide), the sensor unit can fit into a variety of mounting locations. $795; digitalmarinegauges.com.
Thanks to today’s highly accurate digital fuel-flow technology, boating anglers no longer need to guess when it comes to how much fuel the boat is consuming, how far they can run and how long they stay out to fish.
