Small Outboard Motors: What They Cost to Run, Not Just to Buy
The sticker price is the loudest number. The quiet ones, petrol per hour, servicing, and how many kilos you carry to the ramp, decide whether you love the motor in year three.
Small outboard motors are portable engines, roughly 2.5 to 30 HP, that clamp or bolt onto the back of a small boat and include their own propeller, steering tiller and, for petrol models, fuel system.
Tash and the little notebook in the glovebox
Tash is an accountant, so when she bought a second-hand 4.2 m (14 ft) tinnie for chasing flathead in the estuary, she started a notebook. Ramp fees, bait, petrol, the lot. The old two-stroke on the back came with the boat and, according to the notebook, was drinking close to double what the seller had promised.
By March she had a column of numbers that did not lie. The old motor cost her more in fuel and fiddly repairs each season than the repayments on a new one would. It also left a blue haze over the ramp that made her feel like the least popular person in the car park.
She swapped to a Suzuki DF15A. The first full day on the water used just over half the petrol of the old motor for the same run to the channel markers and back. The notebook now has a new column headed “savings”, and it grows every weekend.
The lesson is not “buy the dearest motor”. It is count the cost of every hour, not just day one. A small four-stroke that sips petrol and starts first pull is the cheapest motor you will ever own.
How much petrol does a small outboard motor use?
A small four-stroke uses roughly 1 litre per hour at 2.5 HP and around 10 litres per hour at 30 HP, flat out. Cruise at three-quarter throttle and those numbers drop noticeably.
| Size class | Approx. weight | Petrol at full throttle | Best for |
|---|---|---|---|
| 2.5–3.5 HP | 13–19 kg (29–42 lb) | about 1–1.5 L/h | Tenders, canoes, short hops |
| 4–6 HP | 21–27 kg (46–60 lb) | about 1.5–2.5 L/h | Inflatables, small sailboats |
| 8–10 HP | 37–45 kg (82–99 lb) | about 3–4 L/h | 3.5–4 m tinnies |
| 15–20 HP | 44–52 kg (97–115 lb) | about 5–7 L/h | 4–4.5 m fishing boats |
| 25–30 HP | 70–80 kg (154–176 lb) | about 8–11 L/h | 4.5 m+ boats, two or three aboard |
| Torqeedo electric | about 8–18 kg (18–40 lb) with battery | No petrol, recharge from mains | Quiet dams, tenders, trolling |
Figures are typical ranges for current four-strokes; your load, hull and prop will move them. Always check the maker’s spec sheet for exact weights.
What does it cost to keep a small outboard running each year?
Expect an annual service, fresh oil, a gear oil change, and a new water pump impeller every couple of seasons. Small motors are cheap to maintain because most jobs are owner-friendly.
- Four-strokes need no oil mixing; you top up engine oil like a car.
- Fuel-injected (EFI) models such as the Mercury 20 EFI start easier and trim fuel use further.
- Electric motors skip oil, spark plugs and fuel stabiliser entirely; budget for a charger and battery care instead.
- Flushing with fresh water after salt runs is free and adds years.
Small outboard motors worth their running costs
Each pick below earns its place on fuel, weight or value. Prices are starting prices in USD.
Small outboard motors: FAQ
Are small four-stroke outboards cheaper to run than two-strokes?
Usually yes. Four-strokes burn noticeably less petrol per hour, need no two-stroke oil, and run cleaner. Every petrol motor we sell is a four-stroke.
How often does a small outboard need servicing?
Most makers call for a first service after the break-in period, then every 100 hours or once a year, whichever comes first. Your owner’s manual has the exact schedule.
Is an electric small outboard cheaper over time?
For short, regular trips it often is, because charging costs little and there is almost no routine servicing. For long runs at speed, petrol still wins on range.
What is the heaviest small outboard one person can carry?
Most people can carry up to about 27 kg (60 lb) comfortably, which covers motors to 6 HP. From 9.9 HP up, plan on two people or leaving the motor on the boat.
Buy the motor your fuel budget will thank you for.
Send us your boat and how you use it. We will match a size that is cheap to own.