How to Choose the Right Outboard Motor for Your Boat (2026 Buyer’s Guide)

Buying an outboard motor is one of those decisions that’s easy to get wrong if you go on horsepower numbers alone. Shaft length, control type, fuel type, and where you actually boat all matter just as much as the HP rating on the cowling. This guide walks through exactly how to match a motor to your boat, using the same questions our team at Wave Engines works through with customers every day at our South Melbourne showroom.

Start With Horsepower — But Don’t Stop There

The most common mistake first-time buyers make is picking a motor based on what “feels right,” rather than what their boat is rated for. As a rough guide, planing boats need approximately 25HP per 1,000kg of total loaded weight (motor, fuel, passengers, and gear included). But the number that actually matters is on your boat itself: every vessel has a maximum horsepower rating stamped on its compliance plate, usually near the transom, and that figure should never be exceeded — it’s both a safety limit and, in most states, a legal one.

If you’re not sure how to translate your boat’s weight and hull type into the right HP bracket, our motors are grouped by power range:

• 2.5HP – 9.9HP Portable Outboards — tenders, tinnies, and sailboat auxiliaries
• 20HP – 60HP Mid-Range Outboards — aluminium dinghies, punts, and small runabouts
• 70HP – 115HP Performance Range — centre and side console fishing boats
• 115HP – 300HP+ High Horsepower Outboards — offshore centre consoles, cruisers, and twin-rig setups

Not sure where you fit? The HP Finder tool on our site asks for your boat length, primary use, transom depth, and budget, and matches you to compatible motors in a couple of clicks — or you can contact our team directly with the same details.

Get the Shaft Length Right

Shaft length is measured from the top of the motor’s clamp bracket down to the cavitation plate, and it’s just as important as horsepower — the wrong length affects handling, fuel efficiency, and how well the propeller stays submerged.

• Short (15″) — suits most small tinnies and inflatables, like the Yamaha F2.5BMHS 2.5HP or Honda BF20D3SH 20HP
• Long (20″) — suits most fibreglass runabouts and larger aluminium boats, like the Yamaha F9.9LEB 9.9HP or Mercury 30ELPT 30HP
• Extra Long (25″) — suits pontoons and boats with deeper transoms, like the Tohatsu BFT150A 150HP

Measure your transom height from the top edge down to the bottom of the hull, and compare it against the spec sheet for the motor you’re considering. You can also filter our full range by Short Shaft (15″), Long Shaft (20″), or Extra Long (25″) directly. If in doubt, send us that measurement before you order.

Tiller or Remote Control?

This comes down to how your boat is set up, not personal preference alone.

A tiller control motor is steered and throttled directly from a handle on the motor itself — the simplest setup, and the standard choice for small tinnies. A remote control motor connects to a steering wheel, binnacle throttle, and control cables, which is what most fibreglass boats with a centre or side console are built around — for example the Suzuki DF50AV 50HP and Yamaha F90XB 90HP both ship as remote mechanical control. Most models above 15HP, across our Yamaha, Mercury, Honda, Suzuki and Tohatsu ranges, are available in both configurations, so this rarely limits your brand choice.

Why We Only Sell Four-Stroke Outboards

Every motor we stock — Yamaha (2.5HP–150HP), Mercury (3.5HP–150HP), Honda (2.3HP–250HP), Suzuki (2.5HP–200HP) and Tohatsu (9.9HP–115HP) — is a modern four-stroke engine, sourced through authorised supply channels rather than grey-import routes. Four-strokes run quieter, burn less fuel, and need less maintenance than the older two-stroke designs they’ve largely replaced, which is why you won’t find any 2-strokes in our range.

Most current four-stroke outboards are also rated for both fresh and saltwater use, though saltwater series motors typically add extra corrosion protection — stainless hardware, sacrificial anodes, sealed components — that’s worth having if you’re regularly on the bay or ocean. A freshwater-focused motor used occasionally in salt will generally hold up fine too, provided it gets a thorough freshwater flush after every outing.

Freight, Pickup, and What Happens After You Order

Wave Engines ships across every Australian state and territory using flat-rate freight — no postcode surcharges, no calculated quotes. Orders under $5,000 (inc. GST) are a flat $220 freight fee, and orders of $5,000 and over ship free, applied automatically at checkout. Delivery typically takes a few business days from dispatch, with metro VIC, NSW, QLD and SA generally at the faster end, while WA, NT, TAS and remote postcodes may take a little longer. Full details, including how damaged-in-transit claims are handled, are on our shipping policy page.

Prefer to collect in person? Free in-store pickup is available from our South Melbourne showroom at 85 Tope Street — select “Pick Up In Store” at checkout and we’ll email you once your motor is ready, usually within 1–2 business days. Free on-site parking is available, and store hours are Mon–Fri 8:00AM–5:30PM and Sat 8:30AM–1:00PM.

If you’d rather see the motor before you commit, that’s exactly what the showroom is for — come in during business hours, ask questions, and get advice tailored to your boat and your budget.

Returns and Warranty, in Plain English

Change-of-mind returns are accepted within 30 days of delivery or collection, provided the motor is unused, uninstalled, and in its original packaging with all accessories and documentation. Once a motor has been installed, mounted, or started, it’s no longer eligible for a change-of-mind return — though this doesn’t affect your rights under the Australian Consumer Law if there’s a genuine fault. Full terms are on our returns policy page.

Every motor also carries the manufacturer’s standard Australian warranty, with terms varying by brand and model — see our warranty information page for specifics, and we’ll confirm the exact current terms for your motor before you buy. Because Yamaha, Suzuki, Honda, Mercury and Tohatsu all have dealer networks across the country, warranty service is accessible wherever you’re based, not just in Melbourne.

If you need finance to spread the cost, take a look at our finance options, or check our FAQ page for answers to the most common questions we get about sizing, shipping, and servicing.

The Short Version

1. Check your boat’s compliance plate for max HP — never exceed it
2. Measure your transom for the correct shaft length
3. Match tiller vs. remote control to your existing setup
4. Choose a genuine four-stroke motor rated for your fresh or saltwater conditions
5. Decide between AU-wide delivery and free in-store pickup at 85 Tope Street, South Melbourne

Still not sure which motor is right for your boat? Try our HP Finder tool or contact Wave Engines with your boat’s length, hull material, and how you use it — we’ll help you land on the right HP, shaft length, and brand, no guesswork required.