Boat EconomicsUse and Trip Economics
What Will This Outing Cost in Fuel?
A cost-planning estimate for a specific trip, running hours, consumption, and price, with a contingency range. Not navigation or safety guidance.
A single fuel-price headline doesn't tell you what a trip actually costs
Fuel cost per gallon gets the attention, but a trip's real cost depends just as much on your boat's actual consumption rate and how many hours you'll actually run. This engine turns those three numbers into a planned cost and a contingency range, rather than a single misleadingly precise figure.
How this is calculated
Running gallons multiply hours by your consumption rate, doubled for a round trip, and adjusted up if you add a load percentage for passengers or gear. Idle or trolling hours are added separately at their own, usually lower, consumption rate. Total gallons times your fuel price gives the planned cost; your stated contingency percentage adds a buffer on top for the high end of the range.
Worked example
A 2-hour run each way at 5 gallons per hour is 10 gallons one-way, or 20 gallons round trip. At $4 a gallon, that's $80 planned, with a 20% contingency putting the range at $80 to $96. Add an hour of trolling at 1 gallon per hour and the total rises to 22 gallons, or $88 to $105.60 with the same contingency.
Common mistakes
Using a manufacturer's best-case consumption figure without any contingency tends to understate real trip cost once load, sea state, and throttle habits are factored in. The other common mistake is forgetting the return leg entirely; the round-trip checkbox above exists specifically to catch that.
Frequently asked questions
Is this a navigation or safety tool?
No. This is a cost-planning estimate only. It does not check tank capacity, route feasibility, or give any navigation guidance. For a fuel-reserve and range check, use the Boat Range and Fuel Reserve Planner instead.
Where should my consumption rate come from?
Your own observed fuel burn at your typical cruising RPM is the most reliable source. Manufacturer specs are a reasonable starting point if you have not measured your own yet, but real consumption varies with load, trim, and sea state.
Why does contingency only raise the high end of the range?
The low end assumes your stated consumption holds exactly; the contingency percentage adds a buffer on top for the real-world variation that pushes consumption up, not down, so the range reflects "plan for at least this, budget up to this."
What about idle time at anchor or trolling?
Idle and trolling fuel burn is usually much lower per hour than running speed. Enter it separately in the advanced section with its own consumption rate rather than folding it into your running-hours estimate.