If you’re interested in powerboats of just about any type, ranging from speed boats to sportfishing yachts, you need to know all about outboard motors. Outboards have been around for over a century – and these days, they’re the fastest-growing segment of the marine power market. That’s in no small part because outboard engine technology has advanced by leaps and bounds in recent years, and today’s modern outboard motors are better than ever. Let’s start with the basics, then we’ll look at some of the newest outboard models this year.
What Are Outboard Motors?
Outboard motors are fully contained marine propulsion systems that can be mounted onto the transom of a boat. The powerhead, driveshaft, and a lower unit with running gear (the part with the propeller that sits underwater) are all contained together in one unit. Like most marine power systems, the engine spins a shaft, which then spins a propeller shaft, which in turn spins a propeller to create thrust.
Outboard motors have several advantages as compared to other marine propulsion systems. A boat manufacturer can take an outboard and bolt it right onto the back of a boat, hook up the control cables and fuel lines, and the boat’s ready to go. That greatly simplifies the boatbuilding process, because with an inboard or stern drive they’d have to mount the motor and then line up and attach the drive system.
It also makes the engine very easy to replace in case of failure; it improves a boat’s handling because outboard motors provide articulated thrust as opposed to the rudders used with inboards, and modern outboards offer an excellent power-to-weight ratio as compared to the other options. See Inboard or Outboard: The Boat You’ll Buy Next, for more a more in-depth inboard-versus-outboard comparison.
History and Evolution Of Outboard Motors
Ole Evinrude, a Norwegian immigrant who arrived in the U.S. at age five in 1882, is usually credited with inventing the first outboard motor in 1906. The tale is quite famous, and with good reason – it’s an excellent example of American ingenuity. According to the lore, Ole and his fiancé Bess were picnicking on an island in Okauchee Lake. When Bess expressed a desire for ice cream, Ole jumped into their rowboat and took off, rowing vigorously for the mainland. But the two-and-a-half-mile trip was just too far, and by the time he returned to Bess the ice cream had all melted.
Ole knew there had to be a better way, and he was right: he invented and built a 1.5-horsepower outboard motor that could be clamped to the back of a rowboat. He and Bess (by then married) produced 25 outboards in 1909 and sold them all in one day. Thus, Evinrude Motors was born.
Obviously, outboards have come a long way in the past century. Through the earlier years of development outboard sizes gradually increased, until 1975 when the first V-6 outboards finally broke the 100-horsepower barrier and put 175- and 200-horsepower outboards on the market. The biggest turning point in modern times, however, came with EPA emissions standards first introduced in the 1990s and then phased in over a number of years.
New emissions standards forced outboard manufacturers to turn in a different direction, completely replacing the carbureted two-stroke engines they depended on and instead of developing cleaner-burning four-stroke technology. While four-stroke engines were significantly more efficient than two-strokes of the time, they were also much heavier and more complex, so there was a lot of trial and error involved in the process. But eventually, all of the major outboard motor manufacturers with the lone exception of Evinrude made the switch for four-strokes.
Evinrude instead developed two-stroke direct-injection in order to meet emissions standards, but early versions were a disaster and Outboard Motor Corporation (by then Evinrude’s parent company) filed for bankruptcy in 2000. It was eventually bought by Bombardier Recreational Products (BRP). BRP then made major reinvestments in two-stroke technology and their new E-TEC G2 outboards were introduced. These outboard motors were extremely efficient and clean-burning, but in 2020 Evinrude went out of business and with it, production of the last of the two-strokes ceased.
Current Outboard Motor Market
In recent years, the biggest push in the outboard engine market has most certainly been producing larger, more powerful motors. In 2007 Yamaha introduced a monstrous V-8 outboard, the F350, producing 350 horsepower. Soon it followed up with even more power, in the form of the F425. And in 2023 it boosted the top-end even more, with the F450. In 2011 industry newcomer, Seven Marine rolled out a shocking 557-horsepower outboard, at the time the most powerful outboard ever built, based on a marinized 6.2-liter GM LSA Gen IV V-8 engine designed for the Cadillac CTS-V. Just a few years later, they’d top this mark with their own 627-horsepower version shortly before being purchased by Volvo Penta. In 2020, however, Volvo Penta shut down Seven Marine’s operations and they are no longer built today. Meanwhile, Mercury Marine constantly upped the ante with their Verado models, bringing a 350, then 400, then 450 horse models to the market. Then in early 2021 they shocked the outboard world by introducing a 600 horsepower V-12 outboard with a two-speed automatic transmission and a steerable gearcase; get the full scoop on the 600 Verado at Mercury’s V-12 Mega Motor: 600 Horses of Pure Power. Suzuki followed a similar bigger-is-better path by introducing the DF350A V-6, a model notable for its twin-propeller lower unit.
But all of the interesting outboard developments haven’t taken place with these huge powerplants. As outboard-powered boats have grown larger and larger and outboard manufacturers have matched this demand with increasing horsepower, there have also been some big developments in the world of small outboard motors. EFI has been incorporated into smaller and smaller models and Suzuki made a breakthrough in 2014 when they introduced battery-less EFI to small, portable outboards like the DF25A and the DF15A. Yamaha quickly followed up with battery-less EFI when soon after, they introduced a series of engines including their new F25, F75, and F90 outboards. And yes, that F25 features battery-less EFI.
Newest 2023 Outboard Motors
In 2023, the big news is still Mercury’s introduction of the V-10 350- and 400-hp Verados. Filling the gap between their existing V-8 ad the big V-12, the V-10s are naturally aspirated, and replace the supercharged V-6 Verados in this horsepower range. Surprisingly, however, Mercury managed to keep the weight gain down to a very modest 27-pounds over the V-6. It also has some very techy features, including an optional dual-mode 12/48-volt alternator that creates enough juice to completely replace a generator, when used in conjunction with Navico’s lithium-ion Fathom system.
Also new in 2023 is Suzuki’s upgrade of the DF350A. Now available as the DF350AMD and the DF300BMD, new models enjoy an enhanced gearcase designed for better longevity, efficiency, and speed. The new models also have integrated steering systems.
Honda’s most recent developments date back to redesigned midrange motors in late 2021. Their BF115 and BF150 were upgraded and the BF135 replaced with the BF140. This new line is “smarter” than before, incorporating an interface with the HondaLink app for remote monitoring and ownership information. They’re available with either digital or mechanical controls, and feature optional tilt limit switches and push-button start control. In 2023 Honda also showed a prototype electric motor at the Dusseldorf boat show, but didn’t provide details about the unit. It could be impactful, however, since Honda has developed a battery-sharing platform based on a 1.3-kWh lithium-ion power-pack for use across its range of “small mobility vehicles” and electric scooters.
Electric outboards are also becoming more widely available in ever-growing horsepower sizes. While few companies have managed to penetrate this market with a wide range of offerings, German company Torqeedo now has a model line ranging from one to 80 horsepower, and ePropulsion has rolled out a line ranging up to 9.9 horsepower. Mercury introduced it’s Avator 7.5e electric outboard (which produces approximately 3.5 horsepower) in 2023, and says 20e and 35e models will be released soon.
The introduction of diesel outboard engines has also made news in recent years. Other outboard diesel motors have come and gone, but in 2019 Cox introduced the largest yet produced, the CXO300. The Cox diesel was designed from the ground-up (previous diesel outboards were adapted from existing diesel powerheads designed for other purposes) to be an outboard incorporating common-rail technology. And at about the same time, a Swedish company called Oxe announced it would be building 150- to 300-horse diesel outboards based on a marinized GM diesel block, which are in use out on the water today.
You can check out our huge range of Outboard Motors on the site today.
Future of Outboard Motors
Where will the future of outboard motors lead? Almost certainly to a continued mix of technology, as we see in today’s market. Gasoline, diesel, and electric options will all surely play a role and no one system can be expected to dominate the market, as each has its own set of advantages and disadvantages.
It’s important to note that the growing dominance of electric and hybrid-electric power systems we see in vehicles designed for use on land isn’t likely to be mirrored in the marine world, at least not in the near term, because the application of technology is so different. Regenerative braking, for example, (which uses an automobile’s braking to feed power back to a car’s batteries) isn’t possible in a boat. And unlike automotive applications boat motors generally run at high RPM for extended periods, quickly sapping the juice out of the battery banks. On small boats the power and range limitations aren’t too problematic and year by year small electric outboards gain ground. But for larger boats travelling for long distances this remains a big problem. So, internal combustion outboards aren’t likely to go away any time soon.
What we can expect in the immediate future, however, is for modern outboards to join the IoT. All of the major manufacturers now have apps that can “talk” with their larger, more advanced models, providing everything from diagnostic information to routine maintenance alerts. The biggest recent news is Yamaha Marine’s purchase of Siren Marine, a provider of remote monitor and control systems for boats. Announced in late 2021 and finalized in early 2022, Yamaha’s purchase of Siren portends their drive towards complete connectivity, much as we’ve seen in the high end automotive world in recent years.
Outboard Motor Brands
Considering the popularity of outboard engines, one might think the field of competing for outboard motor brands would be fairly large. However, there’s a limited number of major players. These include:
Evinrude ceased production in 2020, citing difficulties brought about by the Covid-19 pandemic.
Honda Outboard Motors
Honda Marine offers four-stroke outboards from 2.3 to 250 horsepower, including jet outboards from 40 to 105 horses.
Mercury Outboard Motors
Mercury Marine’s line-up includes four-stroke outboards from 2.5 to 600 h.p. They also have jets from 25 to 80 horsepower. A separate division, Mercury Racing, offers a 450-horsepower supercharged model. Mercury entered the electric outboard market just this year with the introduction of the Avator. Learn more about the history of Mercury Marine and their engines.
Minn Kota Outboards
Minn Kota manufactures a line of electric motors which can be bow- or transom-mounted, ranging from 30 pounds of thrust to 112 pounds of thrust (approximately 1.5 to 2 horsepower)
Motorguide Outboard Motors
Another electric motor manufacturer, MotorGuide offers bow- and transom-mount motors between 30 and 109 pounds of thrust.
Seven Marine Outboards
After purchasing Seven Marine in 2017, Volvo Penta ceased production in 2020.
Suzuki Outboard Motors
This manufacturer’s line-up of four-stroke outboards ranges from 2.5 to 350 horsepower and includes two of the few twin-propeller outboard engines (the DF350AMD and the DF300BMD) on the market today. Learn more about the history of Suzuki Marine and their outboards.
Tohatsu Outboard Motors
Tohatsu’s line of four-stroke gasoline outboards ranges from 2.5 to 250 horsepower, and the company offers a limited number of two-stroke low-pressure direct-injection (TLDI) models. Tohatsu has a rather unusual five-horse outboard as well, which runs on LPG. They also produce jet-drive options from 25 to 115 horsepower.
Torqeedo Outboard Motors
The biggest player in the electric outboard motor market, Torqeedo makes outboards from one to 80 horsepower.
Industry giant Yamaha Outboards has a four-stroke model line ranging from 2.5 to 450 horsepower, including the only direct-injected four-strokes on the market, the F425 XTO and F450 XTO. They also produce jet outboards from 40 to 150 horsepower and an electric propulsion system called the Harmo. Learn more about the history of Yamaha Marine and their outboards.
Outboard Motors FAQ
When it comes to outboard motors, two of the questions we hear asked all the time are “what’s the biggest outboard?” and “which is most fuel-efficient?” So let’s take a quick look at information regarding these topics.
What are the Most Powerful Outboard Motors?
Everyone wants to hear about the biggest, most powerful outboards in existence. The top 10 most powerful outboards are:
- Mercury Verado 600
- Mercury Racing 450R
- Yamaha F450 XTO
- Yamaha F425 XTO
- Mercury Verado 400
- Suzuki DF350AMD
- Mercury Verado 350
- Yamaha F300
- Suzuki DF300BMD
- Mercury Verado 300
You should think about how big an outboard will actually fit on your boat however. We’ve put together an article on this subject for you here.
What are the Most Fuel-Efficient Outboards?
Setting aside electric outboards and alternative fuel outboards, size and fuel efficiency often go hand in hand – the smaller an outboard is, the better economy it’s likely to post. As a rule of thumb, the vast majority of the four-stroke outboards on the market offer very competitive efficiency and rarely differ by more than a few tenths of a mile per gallon or so in the similar horsepower ranges.
On top of the similar nature of four-stroke outboard efficiency, due to the number of variables in the boats they’re mounted on, very accurate apples-to-apples comparison between different outboards is rarely possible. Different model outboards may post slightly better or worse efficiency numbers on one type of hull design as compared to another. And boat manufacturing is not an exact science; often the same model boat will vary from one hull to the next in weight, sometimes by hundreds of pounds. So testing two outboards side by side on the same model boat can provide unreliable results.
Finally, note that there are other variables that can come into play. Sea conditions, for example, have a big impact on efficiency and can change from one moment to the next. Then, there’s outboard propellers choice to consider. And there are also variables that can make an outboard engine perform better, as well as a few techniques that can be used to make a boat engine run faster.
The bottom line? Today’s outboard motors are far more efficient than they were a decade or two ago across the board, and it’s rare to see major differences among modern outboards of similar horsepower.
Today, the popularity of outboard engines is at an all-time high. Even on boat types that have traditionally been built with stern-drive and inboards, such as runabouts and cruisers, more and more outboard models are being introduced every year. In fact, approximately four out of five new powerboats sold in the United States are now powered by an outboard motor, while stern drive sales have steadily declined and inboard options have remained flat. And this shouldn’t come as a surprise. Boaters regularly cite the easy maintenance, high reliability, and quiet operation as reasons why they prefer outboard motors over the other options – and truth be told, today’s outboards really are better than ever before.
Editor’s note: This article was originally written in September of 2019 and has been updated annually, most recently in February of 2023.