Manufacturer Fuel Data
Browse real-world GPH data by engine manufacturer.
Understanding Boat Fuel Consumption
Unlike cars, where fuel efficiency is measured in miles per gallon (MPG), boat fuel consumption is measured in gallons per hour (GPH). Boats face constantly varying water resistance, so we measure how much fuel the engine burns over time instead.
SFC
Specific Fuel Consumption
Rate of fuel burn per horsepower per hour (lbs/HP/hr):
- Gas 0.50 lbs/HP/hr — four-stroke gasoline
- Diesel 0.40 lbs/HP/hr — diesel engines
FSW
Fuel Specific Weight
Weight of one gallon of fuel (lbs/gal):
- Gas 6.2 lbs/gal — ethanol-free gasoline
- Diesel 6.9 lbs/gal — diesel fuel
The Formula
GPH = (SFC × HP) / FSW
Where SFC is specific fuel consumption, HP is engine horsepower, and FSW is fuel specific weight.
Worked Examples
300-HP Diesel
17.4 GPH
GPH = (SFC × HP) / FSW
GPH = (0.40 × 300) / 6.9
GPH = 120 / 6.9
GPH = 17.4
GPH = (0.40 × 300) / 6.9
GPH = 120 / 6.9
GPH = 17.4
300-HP Gasoline
24.2 GPH
GPH = (SFC × HP) / FSW
GPH = (0.50 × 300) / 6.2
GPH = 150 / 6.2
GPH = 24.2
GPH = (0.50 × 300) / 6.2
GPH = 150 / 6.2
GPH = 24.2
⚠️ Keep in Mind
- This formula applies at Wide-Open Throttle (WOT). Cruising speeds typically consume significantly less fuel.
- Engines with direct or electronic fuel injection may yield higher fuel efficiency than these estimates suggest.