Boat Fuel Cost Calculator
Work out what your boat costs to run on fuel today, and what it would cost on electric.
This boat fuel cost calculator works out your fuel consumption and running costs, then compares them with an electric motor. Enter your current engine, how many litres it burns per hour when cruising and how much you use your boat each year. Fuel prices come from the European Commission’s Weekly Oil Bulletin for the country you choose, electricity prices from Eurostat. The electric cost uses New Stream’s average consumption at 7 knots: 4.5 kW for a displacement boat, 10 kW for semi-displacement and 12 kW for planing hulls.
- Diesel
- —€/L
- Euro-super 95
- —€/L
- Diesel, last 12 months
- —
- Electricity, business
- —€/kWh
Loading current prices.
The calculation in detail
What one hour of cruising means for each system, and the total cost over ten years. Every figure updates with your choices above.
- Burned today —
- Drawn from the battery —
- Drawn from the grid —
- Electricity cost per hour —
- Current engine
- New Stream
Show values as a table
| Year | Current engine | New Stream | Difference |
|---|
One year in detail
| Item | Current engine | New Stream |
|---|
Your scenario
How many litres per hour does a boat engine use?
Cruising fuel consumption depends less on engine power than on hull type and speed. A displacement boat at hull speed (6–8 knots) uses about a third of its rated power; a semi-displacement boat at 9–14 knots uses close to half, and a planing boat at 3,500–4,500 rpm around half. The table shows the typical ranges the calculator suggests.
| Engine power | Displacement, diesel | Semi-displacement, diesel | Planing, 4-stroke petrol |
|---|---|---|---|
| 20 HP | 1–2 L/h | 2–3 L/h | 3–4 L/h |
| 30 HP | 1.5–2.5 L/h | 2.5–4 L/h | 4–6 L/h |
| 40 HP | 2–3.5 L/h | 3.5–5.5 L/h | 5.5–8 L/h |
| 50 HP | 2.5–4 L/h | 4–6.5 L/h | 7–10 L/h |
| 60 HP | 3–5 L/h | 5–8 L/h | 8–12 L/h |
| 75 HP | 3.5–6 L/h | 6–10 L/h | 10–15 L/h |
| 90 HP | 4–7.5 L/h | 7.5–12 L/h | 12–18 L/h |
| 100 HP | 4.5–8 L/h | 8–13 L/h | 13–20 L/h |
| 115 HP | 5.5–9 L/h | 9–15 L/h | 15–23 L/h |
| 150 HP | 7–12 L/h | 12–19 L/h | 19–29 L/h |
| 200 HP | 9–16 L/h | 16–26 L/h | 26–39 L/h |
| 250 HP | 11–19 L/h | 19–32 L/h | 32–48 L/h |
| 300 HP | 13–23 L/h | 23–38 L/h | 38–58 L/h |
Values are per engine at the usual cruising speed for each hull type; full-throttle consumption is roughly double. Ranges are compiled from outboard performance data, diesel propeller load curves and boat tests. Your boat’s real figure depends on weight, propeller, hull fouling, cruising speed and sea state. The most accurate number comes from dividing the fuel you buy by your engine hours; enter it in the calculator above.
How the boat fuel cost calculator works
The calculator builds the two sides separately. Your current cost comes from your real consumption; the electric cost comes from New Stream’s cruising consumption. The comparison takes four steps.
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Your current cost
Your hourly cruising consumption is multiplied by your annual engine hours and the current fuel price in the country you choose, and engine maintenance is added. This side relies entirely on your data; the calculator warns you if the consumption you enter isn’t possible for your engine power.
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Electric cruising power
New Stream motors are direct drive: the motor shaft turns the propeller shaft directly, with no gearbox in between. With New Stream, average consumption at 7 knots is 4.5 kW for a displacement boat, 10 kW for semi-displacement and 12 kW for planing hulls; the calculation uses the value for your hull type, per motor. The calculator does not estimate consumption from your hull, horsepower or speed; if you have a measured figure for your boat, enter it in the Electric system step.
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From battery to socket
Allowing for charger and cell losses, 91% of the energy drawn from the socket becomes usable in the battery. If you select solar panels, their energy is used first and only the shortfall is drawn from the grid; if daily production covers your cruising, no grid charging is needed at all.
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From energy to money
For New Stream, the kWh drawn from the grid is multiplied by the electricity price. With no oil, filters, belts or injectors in the motor, maintenance defaults to zero. The difference between the two sides is your annual saving.
Assumptions and sources
| Fuel prices | European Commission Weekly Oil Bulletin: consumer prices including taxes for Euro-super 95 and automotive diesel in the selected EU country, updated weekly; last 12 months from the same bulletin. Türkiye: current pump prices in Muğla, converted at the Central Bank of Türkiye euro rate. Other country: EU average — enter your local price. |
|---|---|
| Electricity | Eurostat, all taxes included, latest half-year. Business: non-household consumers, 20–499 MWh/year band. Household: 2,500–4,999 kWh/year band. Marinas often charge more; choose Marina price and enter your own figure. |
| Exchange rates | European Central Bank daily reference rates (GBP, TRY). |
| Electric cruising consumption | Per motor, New Stream average consumption when cruising at 7 knots: displacement 4.5 kW, semi-displacement 10 kW, planing 12 kW. These are fixed values, not estimates; you can enter your own. |
| Consumption check | The typical consumption suggestion and the plausibility check are made per engine, based on engine power: an idle share plus a share that rises with load. Diesel full-load efficiency is taken as ≈35%. |
| Usable capacity | 90% of the pack. The pack is chosen per motor; with twin motors each motor has its own pack and total capacity doubles. The remaining share protects cell life and keeps a reserve to get home. |
| Charging time | Charge current × average pack voltage of 83 V; on multi-motor boats one charger per motor pack. Plus 8% for the slower final 10% of the charge; an overnight charge can at most fill the pack; anything beyond that is a top-up during the day. |
| Solar | Horizontal mounting, season average 4 kWh/kWp/day spread over 8 hours. Cruising happens in daylight: energy produced while cruising goes straight to the motor on top of the battery. Energy from idle hours and unused days fills the pack up to its capacity. |
| Maintenance estimate | Current engine: for diesel, €350 a year per engine plus engine power × €0.015 per engine hour; slightly lower for petrol engines. Major overhauls and engine replacement are not included. New Stream: zero. |
| CO₂ | Diesel 2.68 kg/L, petrol 2.31 kg/L; grid electricity from the selected country’s carbon intensity of electricity generation (Ember, via Our World in Data). |
Scope. New Stream systems are designed for displacement and semi-displacement boats cruising at 7–12 knots. Planing hulls and fast boats are currently out of scope. The result on this page is a preliminary calculation, not a quote; our engineering team works out the exact figures from your boat’s displacement, hull form and cruising profile.
Frequently asked questions
How realistic is this calculation?
The current-engine side relies entirely on the hourly consumption you enter; if you take it from your fuel purchases or engine hours, the result fits your boat. The electric side uses New Stream’s average consumption at 7 knots: 4.5 kW per motor for a displacement boat, 10 kW for semi-displacement and 12 kW for planing hulls. If you have a measured figure for your boat, enter it in the Electric system step. We work out the exact value with your boat’s data at the quote stage.
How do I calculate my boat’s fuel cost?
Multiply your hourly cruising consumption (L/h) by your annual engine hours to get litres per year, then multiply by the price per litre. If you don’t know your hourly consumption, divide the fuel you bought over a season by the increase on your engine-hour meter. The calculator does this with current fuel prices, adds maintenance and shows the same use on an electric motor side by side.
Where do the fuel and electricity prices come from?
Fuel prices are the European Commission’s Weekly Oil Bulletin figures for the country you choose, including taxes. Electricity prices come from Eurostat, including all taxes. If your marina charges a different unit price, choose “Marina price” and enter your own figure.
I use tax-free or marked marine diesel. Can I still use the calculator?
Yes. Choose diesel and enter the litre price from your invoice in the “Price per litre” field; the calculation then uses your price instead of the bulletin price.
My country isn’t in the list.
The list covers the 27 EU countries and Türkiye. For any other country choose “Other country (EU average)” and enter your local fuel and electricity prices; your figures replace the averages.
Which shore connection should I choose?
Charging time is usually set by the pontoon, not the boat. A single-phase 16 A socket is available almost everywhere but only fills large packs overnight. A three-phase connection shortens charging considerably. If you don’t know your marina’s socket type, choose single-phase 16 A to see the longest charging time.
What if the battery pack isn’t enough for my daily cruising?
The calculator shows whether your daily cruising fits on one charge and, if not, suggests the smallest pack that works. Other options are a mid-day top-up, solar panels or cruising a little slower. An independent generator can also be planned for extra range.
Why isn’t a payback period shown straight away?
Because the system price is specific to each boat and we don’t have a price list. If you have a quote, enter the amount under “Maintenance, price increases and investment”; the payback period and the ten-year chart are then drawn with it. To get a quote, just send your calculation to the form.
Let’s refine the figures with your boat’s real data
Send your calculation to the quote form. Our engineering team will size the motor, battery capacity and charging setup for your boat. Sizing and quotes are free of charge.
Request a quote with my calculation