Small Outboard Motors: Three Numbers That Pick Your Motor for You
Forget the brochure adjectives. Weight, shaft length and horsepower decide almost every small outboard purchase. Get those three right and the brand becomes a matter of taste.
Small outboard motors are self-contained engines of roughly 2.5 to 30 HP that clamp or bolt onto a boat’s transom, combining engine, gearbox, steering and propeller in one portable unit.
Hamish and the bathroom scales
Hamish had a shed full of opinions from his mates. One swore by 15 HP for everything. Another said nothing under 25 was worth owning. His brother-in-law had a 2-stroke older than Hamish’s ute and refused to discuss it.
So Hamish did something nobody suggested. He carried his bathroom scales down to the shed, stood on them, then stood on them again holding a 20 litre water drum. That extra 20 kg (44 lb) was about all he could comfortably lug from the trailer to the end of the jetty and lift onto his 3.1 metre (10 ft) tinnie’s transom without a helper.
That one test killed half the shortlist on the spot. Anything over roughly 27 kg (60 lb) meant a permanent mount and a trailer every trip. His boat’s plate allowed 8 HP, the transom measured 38 cm (15 in), and the scales said stay light. The answer was a 5 HP short shaft four-stroke at around 25 kg.
First morning out he crossed the inlet to the oyster rocks in ten minutes instead of forty on the oars. Weigh yourself before you weigh up brands.
How heavy are small outboard motors?
Small outboard motors run from about 13 kg (29 lb) at 2.5 HP to around 70 kg (155 lb) at 30 HP. Figures below are typical dry weights for short shaft tiller models; check each product page for the exact number.
| Horsepower | Typical weight | Carry style | Good for |
|---|---|---|---|
| 2.5–3.5 HP | 13–19 kg (29–42 lb) | One hand | Inflatables, tenders, canoes |
| 4–6 HP | 24–28 kg (53–62 lb) | Two hands, short walk | Dinghies, small tinnies |
| 8–9.9 HP | 36–45 kg (79–99 lb) | Two people or a trolley | 3.5–4 m (12–13 ft) alloy boats |
| 15–20 HP | 44–52 kg (97–115 lb) | Usually left on the boat | Planing 4–4.5 m (13–15 ft) hulls |
| 25–30 HP | 65–75 kg (143–165 lb) | Bolted on | Loaded runabouts, longer runs |
| Torqeedo electric | about 8–17 kg (18–37 lb) incl. battery | Splits into two light pieces | Tenders, lakes, quiet water |
Which shaft length do small outboard motors need?
Match the shaft to your transom height: about 38 cm (15 in) takes a short shaft, about 51 cm (20 in) takes a long shaft. Measure from the top of the transom straight down to the bottom of the hull.
Most dinghies and tinnies are short shaft. Sailboats, some catamarans and taller transoms need a long shaft so the propeller stays in clean water when the stern lifts in a swell. Too short and the prop sucks air; too long and you drag extra gearcase and lose speed. Browse by short shaft or long shaft to skip the guesswork.
Small outboard motors worth shortlisting
A spread across the weight classes. Prices shown are starting prices in USD.
How do I narrow small outboard motors down to one?
- Read the capacity plate. Write down maximum HP and maximum load. That caps your list.
- Do the carry test. Lift a known weight the distance you will actually walk. That sets your weight ceiling.
- Measure the transom. 38 cm means short shaft, 51 cm means long shaft.
- Choose fuel. Petrol for range and speed; Torqeedo electric for quiet, short trips and no fuel smell in the car.
- Pick a brand you can service. The nearest dealer for spark plugs, impellers and anodes matters more than a logo.
- Every petrol motor we sell is a four-stroke: no oil mixing, quieter idle, lower fuel use.
- Going electric? Add a spare from our electric batteries and accessories.
Small outboard motors: FAQ
What is the lightest small outboard motor?
Among petrol motors, 2.5 HP four-strokes such as the Suzuki DF2.5 sit around 13–14 kg (29–31 lb). Torqeedo Ultralight electric motors are lighter still and split into motor and battery.
How much fuel does a small outboard motor use?
A 2.5 to 6 HP four-stroke typically burns around 1 to 2 litres per hour at cruise. A 15 to 20 HP uses roughly 4 to 7 litres per hour at planing speed, depending on load and throttle.
Can I lift a small outboard motor on my own?
Most people can handle up to about 6 HP (roughly 25–27 kg) alone. From 8–9.9 HP upward, plan on a helper, a motor trolley or leaving the motor mounted.
Do small outboard motors need registering or licensing?
Rules vary by waterway and boat size. Check with your local boating authority or harbourmaster before your first launch.
Three numbers. One motor. Done.
Send us your plate rating, transom height and carry limit and we will shortlist the fit.