Boat Fuel Consumption
Calculator
Results
- Gallons per hour (US gal/h)
- 15.368852
- Litres per hour (L/h)
- 58.177435
- Fuel weight burned (lb/h)
- 93.75
Aviation and marine results
| Gallons per hour (US gal/h) | 15.368852 |
| Litres per hour (L/h) | 58.177435 |
| Fuel weight burned (lb/h) | 93.75 |
formula-map diagram
- Gallons per hour (US gal/h)
- 15.368852
- Litres per hour (L/h)
- 58.177435
- Fuel weight burned (lb/h)
- 93.75
Aviation and marine relationship
Formula
GPH = hp × load × SFC ÷ 6.1 lb per US gallon= 15.368852459016
Note
This is a simplified model: it applies a standard navigation, performance or seamanship formula to the numbers you entered. True airspeed and density altitude use the ISA troposphere model for dry air and ignore humidity, compressibility and instrument or position error, so they are not a substitute for your aircraft's flight manual or an air data computer. Wind, climb, descent and fuel figures assume a steady wind and a constant speed and fuel flow for the whole leg; they ignore manoeuvring, holding, taxi and start-up fuel, terrain, turbulence and air traffic control routing. Takeoff distance scales an entered sea level figure by a rule-of-thumb percentage per 1000 ft of density altitude and is not a certified performance chart. Weight and balance results depend entirely on the arms and weights you enter and must be checked against the approved loading envelope. Hull speed is the classic 1.34 × √LWL displacement estimate, boat fuel burn is a horsepower-based approximation, anchor scope is a rule of thumb, and the rule of twelfths is a linear approximation of a sinusoidal tide that does not hold in all locations. Always use official charts, tide tables, the aircraft or vessel manuals and current weather, and treat these numbers as planning estimates only.
More in Aviation and marine
See all →Frequently asked questions
What does this calculator estimate?+
It estimates fuel used per hour of operation (or over a trip) based on your boat's fuel burn rate at a given RPM or throttle setting, combined with your planned running time or distance and cruising speed.
Why does fuel consumption per hour increase so sharply at higher speeds?+
Hydrodynamic drag on a hull increases roughly with the square of speed (or faster, near hull speed for displacement hulls), and the power needed to overcome that drag increases even more steeply, so fuel burn per hour rises disproportionately as you push the throttle up, especially past the most efficient cruising RPM.
What's the difference between fuel burn per hour and fuel efficiency per mile?+
Fuel burn per hour tells you the rate of consumption at a given speed, while fuel efficiency (miles per gallon or liters per nautical mile) tells you how far you get per unit of fuel — and because higher speed increases burn rate faster than it increases speed itself, the most fuel-efficient speed is often well below a boat's top cruising speed.
What's a common misconception about running at a slower speed to save fuel?+
While slowing down generally reduces fuel burn per hour, going too slow on a planing hull can push it back off plane into a displacement mode that is actually less efficient per mile than a moderate planing speed. There is often a specific 'sweet spot' RPM for best range, not simply 'slower is always better.'
How should reserve fuel be handled separately from this calculation?+
This calculator estimates trip fuel burn based on planned running time, but a safety reserve — commonly one-third of total fuel for the classic 'rule of thirds' (out, back, reserve) — should be added on top, since actual conditions, load, and sea state can increase real consumption above the calculated estimate.