Choosing a small outboard

A guide to choosing an outboard engine for your small sailboat

Looking for an outboard engine to push your sailboat? Or maybe you’re looking for something to push your tender?

Skip this intro bullshit to get to the actual outboards.

Contents

• What I compared
• Why you (do not) need a small outboard
• Gas, propane, or electric?
• Tips on using a small outboard
• Sizing an outboard for your sailboat
• Choose your outboard

What I compared

I’ve compared gasoline & propane (combusting), and electric outboard engines from (equivalent) 2.5 HP to 6 HP.

For combusting outboards, I’ve compared the big names: Suzuki, Honda, Yamaha, Tohatsu, and Mercury. They’ve spent decades building reputations for reliability and durability. They have international networks for sales, parts, and service. If you don’t have the time to fix it yourself, your neighbourhood lawnmower repair guy can do it blindfolded.

For electric outboards, I’ve compared the big and growing names: Mercury, Torqeedo, and ePropulsion. There are many other electric brands out there, but these are the most conventional outboards as far as usage, durability, and reputation.

Why you (do not) need a small outboard

For small outboards 2.5 HP to 6 HP, expect the best portability and lowest cost to purchase, run, and maintain. The trade-off compared to the next class is limited range, power, and features.

Integrated fuel tank or battery (mostly)

Almost all these combusting outboards have integrated tanks. Some also have connections for external tanks.

The integrated tanks are small. But no external tank and fuel line means more portability, and faster setup and takedown. Arguably, it’s more reliable since the integrated tank is usually above the carburator.

The electric outboards have integrated, removable batteries.

Tortoise, not the hare

Keep in mind that you won’t be breaking any speed records. But these machines are reliable enough to last you years with only a little maintenance.

Light weight, small size

You can carry these combusting outboards with one hand for a few steps and two hands for longer distances. One person can lift them onto a motor mount or into a car trunk. It’s easier to find a place to store them when not in use.

Electric outboards are even lighter.

Versus 8 HP and bigger

If you’re in the market for a combusting outboard that’s 8 HP or more, keep in mind that this is a big jump up in size, weight, and price. And you lose the internal tank on 8 HP and larger engines. As an example, notice the difference in Yamaha’s 6 HP and 8 HP models.

For 8 HP and bigger, make sure your boat’s motor mount can handle the extra weight and find room on board for an external fuel tank.

Mechanically minimal

For combusting outboards, you’ll have to live without fuel injection or electric start. Most of them don’t have an alternator and some combusting outboards don’t have reverse gear.

That’s also a feature. Fewer parts means less to fall apart. Electric outboards have even fewer parts.

Gasoline, propane, or electric?

Choose gasoline or propane when...

You plan to use the outboard frequently or for long, uninterrupted periods. For example, if you cruise with your sailboat and expect to run the outboard for more than an hour or two/day, a combusting outboard is your best choice:

• Range: With a moderate touch on the throttle and some luck, you might squeeze 1.5 hours out of the integrated gasoline tank. And carrying extra fuel isn’t much of a burden.
• Power: There’s just more of it than electric.
• Readily available: We’re still in the era where fossil fuels rule, so combustible fuel is everwhere. Propane isn’t easy to find, but it isn’t hard to find either.

The trade-offs:

• They stink: Gasoline and propane smell when they aren’t burning, they smell when they do burn. Combusting outboards have fewer regulatory emission restrictions than other combustion engines, so those smells are the direct emission of CO₂ and other fun stuff into the air and water.
• Noise: They make a lot of it.
• 'splosions: A misplaced spark will ruin your day. That’s a small risk these days, but combusting fuels like to do risky things like collect in bilges.
• Maintenance and weight: Combustion engines are way more complicated than electric outboards. That means more to repair, maintain, and carry.

Get an electric outboard when...

You have enough charging capacity between trips, whether that’s onboard or at thome. For example, if you only need auxiliary power to get in and out of your marina and you charge your battery at home, a small electric outboard is a better choice than an equivalent combusting outboard.

The advantages of a small electric outboard:

• No smells: Calm down your aunt on Facebook. Yes, there is indirect emission if you charge the battery from fossil-fuel burning power generation. But that’s still a more efficient use of fossil fuels than a combusting outboard. And fossil-fuel burning plants have way stricter emission controls than an outboard. And you have choices for charging the battery, including renewable energy like solar.
• Maintenance and weight: Electric outboards are sooooo much simpler mechanically. That makes them almost maintenance-free and much lighter to carry.

The trade-offs for electric:

• Shorter range: Range anxiety is unfounded these days. For the past few years in the category of these small outboards, electric has practically as much range as combustion.
• Cost: The purchase cost of an electric outboards can be more than a combustion counterparts. But operating costs are much cheaper for electric.

Tips on using a small outboard

Gasoline: Avoid ethanol

For gasoline-powered outboards, ethanol is bad. It’s bad to the point where they become hard to start then idle roughly. Ethanol gums up their adorable little carburators. If you can’t completely avoid ethanol, you can mitigate this somewhat with fuel treatments like SeaFoam Marine Pro.

Thieves like convenience too

Cordless grinders are even more portable than these outboards. Me? I follow the “Less conveninent than my neighbour’s outboard“ school. In other words, make your outboard less convenient to steal than your neighbour’s. Make sure the lock and the chain or plate is stainless steel. Stainless not only resists rust, it takes a few seconds longer to cut than most other metals. On the other hand, thieves appreciate the warm buttery softness of brass that cheap locks are made from.

Sizing an outboard for your sailboat

If the manufacturer doesn’t specify what size outboard to use, you can always crack open a textbook filled with words like coefficient and Schneekluss. Or you can follow your budget and common sense. This guide might also help:

For example, my ol’ O’Day Mariner displaced 1300 lbs and had low freeboard, I sailed it inland where the wind was rarely above 15 knots, and I didn't use it in any strong current. I chose a Honda BF2.3 and it worked great.

I could have chosen an electric outboard, since I only used the engine to get in and out of the marina harbour.

On the other hand, if I had a 3000 lbs catamaran with its consequential high windage, and sailed it in strong currents, I’d consider getting something bigger than 6 HP.

Choose your outboard

At your service

Humbly yours,

Marc, Supreme Purser