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Old 08-02-2017, 11:15 AM   #5
DavidM
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City: Litchfield, Ct
Join Date: Aug 2012
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As the PPs have noted, Flowscans and the newer Maretron meters for older non electronic engines give you exactly the data you are asking for. Newer electronic common rail engines have this feature built in and is usually available on the engine display.

Flowscans have been around a long time and although the electronics is pretty straightforward, the fuel flow sensors need to be very accurate and linear. This is because it takes two for a mechanical diesel- one for total flow and one for return flow so you can calculate the difference as net fuel to the engine.

Their output can be provided on a dedicated display or integrated into some chart plotter's displays.

But a simpler way is to look at your engines prop hp vs rpm curve and its fuel consumption vs rpm curve. This curve which is partially mathematically generated (the fuel consumption curve is derived from the hp curve which is mathematical but fuel is usually is based on real manufacturer test data) is a fairly accurate representation of actual fuel flow. In most cases the prop curve data is within 15% of reality and better in most cases particularly for full displacement hulls where extra hp required to climb over the hump for semi- displacement or planning hulls is not an issue.

These prop curves can be obtained for old and new engines. For new engines look to the manufacturer's website. For older engines they are available on boatdiesel's pdf library.

So, fuel measurement and display has been done before although just looking at the prop curve is a decent substitute.

David
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