Calculated Results
Rate ModeSpeed Scenario Comparison
Compares the same voyage distance at economy, normal, and higher speeds. Fuel rate uses a cubic speed relationship for planning only.
| Scenario | Speed | Time | Estimated Fuel | Estimated Cost | Difference |
|---|
What Is Marine Fuel Consumption?
Marine fuel consumption describes the amount of fuel a vessel uses during operation. Consumption changes with engine size, vessel speed, hull condition, weather, loading, currents, and auxiliary equipment. Reliable estimates help operators plan bunkering, calculate voyage costs, protect fuel reserves, and compare operating strategies before departure.
Formula Used
For direct-rate calculations, voyage fuel equals hourly fuel rate multiplied by sailing time. Sailing time equals voyage distance divided by average speed. For engine-power calculations, energy equals engine power multiplied by load and operating hours. Fuel mass then equals energy multiplied by specific fuel consumption. The calculator converts fuel mass into liters using the selected density.
How to Use This Calculator
Enter vessel details, fuel density, price, tank capacity, and reserve percentage. Choose a direct fuel-rate method or the engine-power and SFC method. Add one or more voyage legs with distance, speed, and load. Include auxiliary, idle, and maneuvering hours. Adjustment fields can represent rough seas, wind, fouling, loading, weather, efficiency changes, and contingency allowances. Press Calculate to update every result.
Understanding the Results
The results summarize sailing time, base fuel, adjusted voyage fuel, reserve fuel, required departure fuel, remaining fuel, operating cost, daily consumption, and fuel efficiency. Range and endurance estimates use the available starting fuel after reserving the selected safety percentage. Tank warnings appear when planned fuel requirements exceed capacity. These outputs support planning rather than replacing manufacturer performance curves or onboard monitoring.
Improving Fuel Efficiency
Small speed reductions can create meaningful savings because resistance often rises quickly with speed. Clean hulls and propellers can reduce unnecessary drag. Balanced loading, suitable trim, route planning, and timely engine maintenance may also improve performance. Operators should compare several speed scenarios while respecting schedules, weather, reserve policies, and safe operating limits. Actual fuel burn should always be checked against vessel logs. Review estimates before every important departure. Reliable voyage planning keeps fuel decisions safer and clearer.
Example Fuel Planning Table
| Vessel Type | Typical Planning Input | Useful Output |
|---|---|---|
| Yacht | Liters per hour | Range and trip cost |
| Fishing boat | Cruise and idle rates | Daily fuel requirement |
| Workboat | Multiple operating modes | Fuel by voyage phase |
| Commercial vessel | Power and SFC | Tonnes per day and voyage cost |
Frequently Asked Questions
What is the simplest way to estimate marine fuel consumption?
Multiply the vessel's hourly fuel rate by expected operating hours, then include reserve and operating-condition allowances.
What does SFC mean?
Specific Fuel Consumption expresses fuel mass used for each kilowatt-hour of engine energy, commonly in grams per kWh.
Why does vessel speed affect fuel use so much?
Higher speeds usually increase hydrodynamic resistance, causing engines to produce more power and consume more fuel.
Should reserve fuel be added to consumption?
Reserve fuel is normally carried in addition to expected consumption to provide a safety margin for delays or changing conditions.
Can I calculate several voyage legs?
Yes. Add legs with different distances, speeds, and engine loads. The tool combines their time and consumption.
How accurate is the calculator?
Accuracy depends on your input data. Vessel logs, manufacturer curves, and recent operating data provide stronger estimates.
What do negative current or efficiency adjustments mean?
A negative adjustment represents a condition expected to reduce fuel demand. Use conservative values and verify them operationally.