Under the hood
Most tools on the market give a single average L/h and multiply by hours under way. It's quick, but it's off by 40 to 50%.
FluviaPro does something else.
When a self-propelled vessel goes from 5 to 8 knots through the water, it does not consume 60% more. It consumes almost three times more. That is the physics of a hull dragging through water: as speed rises, resistance rises far faster.
That is why an average-based calculation is systematically wrong:
An average L/h is what a salesperson can sell without knowing anything about the waterway business. FluviaPro does the opposite: we start by understanding your trade, then we compute.
Every second under way, the system crosses seven parameters.
GPS gives speed over ground. But what burns fuel is speed against the water. Going down the Seine at Conflans, a vessel can do 7 knots over ground while only ‘rowing’ at 6 through the water, the current does the rest. FluviaPro derives the true propulsive speed at every instant.
Downstream or upstream? The engine works twice as hard in the second case. The system automatically detects direction from departure and arrival ports and the direction of each reach.
Not an almanac average. Plugged into the official Hub'eau hydrometric stations (eaufrance.fr), FluviaPro fetches the flow of the river at this very hour. In flood, the Seine current can triple, and so does the empty-return consumption.
An hour of idling at a lock does not burn like an hour cruising at 7 knots. The system splits each voyage into real segments, idle, manoeuvre, eco-cruise, forced run, and applies the matching consumption to each.
A self-propelled vessel loaded with 1,075 tonnes does not drag like an empty one. The load factor is applied in proportion to the tonnage actually on board, not to the one planned on the contract.
FluviaPro counts every lockage performed on the route. A lock is typically 10 to 15 minutes of idling, several litres that never appear in any average calculation.
And that is where it gets interesting. Two 110 m self-propelled vessels of the same power do not consume the same. Hull condition, propeller wear, engine setting, the master's habit of pushing 1,600 rather than 1,500 rpm… each boat has its signature. FluviaPro learns it.
Two 110 m self-propelled vessels of the same power do not consume the same. Hull condition, propeller wear, shaft type, engine setting, the master's habit of pushing 1,600 rather than 1,500 rpm… each boat has its signature.
Every time you record a fuel-up, FluviaPro compares actual consumption to what the model predicted. It then derives a correction factor specific to your boat, which it applies to all future estimates.
| Calibration state | Accuracy | Why |
|---|---|---|
| Before the first recorded fuel-up | ±25% | Already better than any market average |
| After 1 fuel-up | ±15% | Vessel's global correction factor adjusted |
| After 3 fuel-ups | ±12% | The vessel's signature sharpens |
| After 5 fuel-ups or more | ±10% | Stable model, tracks consumption like a counter |
The more you use FluviaPro, the more accurate it becomes. Without doing anything special. Without training. Without entering a single equation.
For the curious
At the heart of FluviaPro is a simple equation inspired by the hydraulic resistance of inland hulls:
Physical model
Consumption (L/h) = a × SOW³ + b
SOW
Speed Over Water, the true propulsive speed through the water, in knots. Different from the speed over ground (SOG) shown by the GPS. Computed as SOW = SOG ± current speed, depending on whether you are downstream or upstream.
a
Hydrodynamic resistance coefficient of the hull, specific to the vessel type. Typically between 0.15 (small Freycinet 38 m) and 0.55 (135 m pusher).
b
Incompressible idle consumption of the engine, around 5 to 15 L/h depending on the motorisation. It is what the engine burns even at standstill.
Cubing the speed through the water is the whole secret: doubling the speed through the water multiplies consumption by eight. That is hull physics. No average L/h can account for that.
This equation is then modulated by five correction factors: operating phase (idle, slow, eco, fast), direction of travel, embarked load, locks crossed, and the calibration factor specific to your boat.
Concrete example
Volvo Penta D16 730 hp at 6.5 knots through the water, vessel loaded to full capacity
Raw consumption = 0.31 × (6.5)³ + 8
= 0.31 × 274.6 + 8
≈ 93 L/h
× full load factor (1.35) → ≈ 126 L/h
× vessel calibration factor → adjusted to your real signature
Sources of the coefficients
The coefficients are cross-checked and refined continuously based on the real fuel-ups recorded by our shipowner customers.
"FluviaPro is not an online spreadsheet.
It is a waterway engineer in your wheelhouse."
At this level of accuracy, diesel consumption stops being a blurred line in your accounts. It becomes a real management tool.
You defend your margin in front of a forwarder with solid numbers, not a finger-in-the-air estimate.
A voyage that burns 30% too much means a leak, a theft, an engine problem · FluviaPro flags it for you automatically.
Every estimated litre becomes a tracked kg of CO₂, compliant with ADEME factors. Your shipper asks for it, you hand it over.
You can simulate two routes and see which saves 200 L. Marne or Seine? The numbers answer.
Every month, the consumption report is embedded into the logbook PDF, with no extra entry on your part.
Try it now
The simulator below runs with zero data from your vessel, just the sector-wide profiles and seasonal currents. Accuracy ±25%. Imagine what it gives in FluviaPro, calibrated on your real fuel-ups.
Free tool
Enter the trip and the vessel, we compute the diesel use, the cost and the CO₂ footprint in a few seconds. Accuracy ±25%, refined to ±10% in FluviaPro with your real calibration.
Imagine what we do with yours.
30-day trial, no credit card.