Calculator
What is your propeller costing you a year?
Marina diesel around A$2.20 a litre changed this arithmetic. Put your engine and hours in — the defaults are honest and every field is editable.
Switching to Autoprop could save you
$176/ year
Documented range $132–$264 · 80 L of diesel
- Over 5 years
- $880
- CO₂ avoided
- 214 kg/yr
- Range gain
- +25%
- A 200 L tank at 6 kn
- +75 nm
Assumptions & sources — read before quoting us
Fixed-pitch → Autoprop savings are typically up to 20% at cruise (documented band 15–30%; one long-term magazine test owner reported over 30% on a 75 hp Yanmar; the French Voiles trial ranked Autoprop best in test for consumption at 6 knots). Folding/feathering → Autoprop gains are smaller and shown as 5–10%. Default burn is derived from engine power (~0.095 L/h per hp at displacement cruise) — enter your logged figure for a real answer. CO₂ at 2.68 kg per litre of diesel. Every projection here is indicative until an engineer sizes the propeller for your actual boat.
Why the saving exists
A fixed prop is right at exactly one operating point
Below it the engine lugs; above it the pitch is wrong and you buy the difference in diesel. Autoprop's blades re-pitch continuously to keep the engine loaded correctly — which is where the documented 15–30% band comes from, and why motor-sailers see the biggest gains.
Australian diesel, 2016–2026 — why the fuel story matters now
MeasuredA$1.18 in 2016 to a A$2.76 peak in April 2026 — marina bowser prices (RQYS, Jun 2026: A$1.99–2.04) track the same curve. Every litre the propeller saves is worth more than it's ever been.
| Year | A$/L (national avg) |
|---|---|
| 2016 | $1.18 |
| 2017 | $1.30 |
| 2018 | $1.49 |
| 2019 | $1.46 |
| 2020 | $1.22 |
| 2021 | $1.46 |
| 2022 | $2.12 |
| 2023 | $1.98 |
| 2024 | $2.07 |
| 2025 | $2.24 |
| 2026 | $2.76 — Apr peak · A$2.16 by Jul |
Fuel burn at 6 knots — same boat, same day
Measured| Propeller | Fuel @6 kn |
|---|---|
| Feathering X | 2.20 L/h |
| Feathering Z | 2.03 L/h |
| Feathering Y | 2.00 L/h |
| Autoprop | 1.40 L/h |
Numbers look interesting?
They get real when the propeller is sized to your boat. Two minutes in the Builder, verified by an engineer within one business day.