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Cathy Yue
Oct 31, 2022  •  10 min

What is an Outboard Motor

If you’re ready to join the fun on the water, and you’re new to the outboard engine on the boat, you’re in the right place. In this article, we will talk about basic information of the outboard motor, the pros and cons of the outboard motor powered by fuel and electricity, main types of the outboard motor, components of the outboard motor, and how the outboard motor works.

Outboard Motor Basic Information

There are generally three types of boat drives including inboard, outboard, and sterndrive. One obvious distinction amoung them is their placement of motor in the boat.

Different from an inboard engine that is usually mounted inside the boat and invisible or a sterndrive that is a combination of inboard and outboard engines, an outboard motor refers to the propulsion system fully installed on the outside of the hull, usually mounted to the exterior of the transom to power the boat.

In addition to offering propulsion, an outboard engine that sits on the boat also offers steering control as it’s built to pivot over its mountings and adjust the thrust’s direction. Often, the outboard motor is the first choice for fishing, recreation, and light commercial inshore boats. These engines provide ease of use alongside reliability.

This is one of our wonderful practical use cases. Perfect boating weekend with ePropulsion Spirit 1.0 Plus 3HP that features a 1276Wh large integrated lithium battery. The outboard motor provides such a great way to enjoy a picnic and sunset. Credit: Michael Nabe.

Advantages of the Outboard Motor

Of all boat drives especially on small and medium size boats, the most frequently used method for motorizing and operating a boat is to utilize an outboard motor. It is an effective way to cruise in the water because of its propulsion system.

Unlike the inboard motor or the stern drive motor(also known as inboard/outboard motors), the outboard motor can be fully removed from the vessel for storage or repair. This is a great feature if you need to avoid obstacles in shallow waters or separate the engine from shallow water to reduce erosion. It can also help with winterizing a boat.

Of all the outboards, the electric outboard engine has greater benefits over its fuel counterpart. Firstly, an electric outboard motor has fewer parts, and in particular there’s no carburetor to ‘gum up’ (the most common cause of petrol motor issues now that petrol contains Ethanol). Secondly, many people are concerned that the cost might be high. The mere fact is that electric outboard motors are undeniably more expensive than petrol outboards, mostly because lithium batteries are expensive. But that extra upfront cost is largely offset by their Lower Lifetime Running Costs, including (almost) no servicing.

Thirdly, if you’re after efficiency, outboards are more suitable than inboards. In boats with an outboard motor, the power-to-weight ratio is quite good because an outboard weighs less than an inboard engine. This improves gasoline efficiency and performance.

Disadvantages of the Outboard Motor

In the past, many people complained that the outboard engine was noisy, but the electric one offers a new solution. With the advent of electric-powered motors, nowadays this issue on both inboard and outboard motors is being substantially addressed. If you cruise in a boat powered by an electric outboard motor, you’ll be able to hear the sounds of nature all around you in lieu of the roar of an engine. For small boats, tenders or maneuvering when fishing, an electric outboard motor is the finest option.

The other main disadvantage to an outboard engine is that it creates larger wakes than its inboard counterpart. If a perfect swimming platform is your personal preference or you like to ski and enjoy other watersports, the inboard engine can better suit your needs as it has better wake control, major towing power and a clear transom for tow ropes. Here we strongly recommend ePropulsion H100 inboard electric motor designed for larger sailing boats and motor vessels between 60 to 100’ (18-30m) with a full displacement up to 200 tons.

For instance, if you want engines for large vessels or watersports, our H100 electric inboard motor is the ideal option. In comparison to its diesel equivalent, it is around two thirds lighter.

Types of Outboard Motor

The outboard motor engine can be divided into the fuel outboard motor and the electric outboard motor in terms of different energy sources.

A Fuel Outboard Motor

Fuel outboard engines are commonly seen on large vessels in the marine industry.

However, the electric propulsion for boats has become more widespread and improves all the time. A growing variety of high quality, long range and large horsepower electric motors for watercraft are available on the market due to ongoing innovation.

An Electric Outboard Motor

The electric outboard motor provides quiet, clean and intuitive solution with much less maintenance than their gasoline counterpart, making your boating experience even better.

Notes: many people mix up the trolling motor with the electric outboard motor when referring to small outboards. Different from the trolling motor that works as an auxiliary power at a slow speed, the electric outboard motor can be used on sailboats and larger vessels in addition to small boats.

As an example, the battery capacity of ePropulsion Spirit 1.0 Plus electric outboard motor is 1276Wh, charges faster, and floats if dropped. The ePropulsion Spirit EVO electric outboard motor even added features including hydrogenation for its battery (eg when mounted on the back of a sailing yacht), options for a removable (instead of folding) tiller, or remote control, built-in GPS (for range/speed info), and backlit displays.

Lithium batteries have made today’s small electric outboard engines not just comparable with, but, for most users, better than their gasoline equivalents. In the realm of recreational boating, particularly among owners of smaller and medium-sized boats, the electric outboard is gradually becoming a valid alternative to traditional gasoline outboards, and in many cases the first choice.

Incredible Range

Navy Series electric outboard motors are impressively efficient to go further and faster.

Navy 3.0

Power (Watt)Speed (mph / kph)Running Time (hh:mm)Range (mile / km)
3003.7 / 613:2049.3 / 79.3
5504.7 / 7.57:2535 / 56.3
10005.3 / 8.64:0021.2 / 34.1
15006 / 9.72:4016 / 25.7
20006.3 / 10.22:0012.6 / 20.4
25008 / 12.81:3512.7 / 20.5
300010.2 / 16.41:2013.6 / 21.9

Navy 6.0

Power (Watt)Speed (mph / kph)Running Time (hh:mm)Range (mile / km)
5004 / 6.518:0072 / 116
10005 / 89:0045 / 72
20006.7 / 10.84:3030.2 / 48.6
30008 / 133:0024 / 39
400011.5 / 18.52:1525.9 / 41.7
500013.5 / 21.81:5024.7 / 39.8
600015 / 24.31:3022.5 / 36.5

* The performance data is based on a 12-foot aluminum boat with one person, powered by one Navy 3.0 Evo with one E80 battery and one Navy 6.0 Evo with one E175 battery, in calm lake water.

Components of an Outboard Motor

The outboard motor is a common addition on boats, knowing their different components is critical to better operating watercraft and being able to do maintenance and repairs.

The Fuel Outboard Motor

An fuel outboard motor usually consists of five main components, including engine, clamp, body components, gearbox and propeller. The engine is an important part of the gasoline outboard motor, which comprises two major mechanisms and five systems.

Two Major Mechanisms: the crank connecting rod mechanism and the valve mechanism (camshaft, ejector rod, valve, etc.).

  • Five Systems: namely fuel supply system, cooling system, lubrication system, ignition system and starting system. It includes crankshaft, piston, connecting rod, cylinder liner, cylinder head, cylinder block, fuel system, cooling system, lubrication system, intake system, and accessories, etc.
  • Clamp Bracket: a complete set of structural parts that fix the outboard motor to the stern plate of the boat, and at the same time provide a complete set of structural parts for the outboard motor to lift and adjust the angle;
  • Body Parts: a complete set of structural parts that fix the engine and gearbox, and has the function of silencing the engine exhaust;
  • Gearbox: a set of shafting structures that change the vertical rotation into the horizontal rotation of the propeller and provides a reduction ratio, and also includes the gearbox housing and the shifting mechanism. The internal combustion engine’s excessive speed and poor torque make it unsuitable for boat propulsion, hence the gearbox is required to boost torque while lowering speed.
  • Propeller: a device that converts the rotational power of an engine into propulsion. Usually for a heavy-loaded boat, we hope that an outboard motor can provide a larger torque, a larger propeller pitch, and higher propulsion efficiency; for a very light boat, the torque requirement is not so high, the propeller pitch is smaller, and the speed is higher. Moreover, the propulsion efficiency is higher, such as higher fuel economy.

No matter how many horsepower they have, all gasoline outboards have a top-mounted structure, which means the engine is on the upper section of the outboard and there is a transmission and shifting mechanism.

The Electric Outboard Motor

Compared with the complicated structures of the fuel-powered outboard engine, an electric outboard has much simpler structures. Electric outboards have fewer parts, safer and easier to store, don’t leak oil or smell of gas, and don’t mind which way up they’re stored (so you can put them in cabin for security).

The core components of an electric outboard are the motor, the battery, and the control circuit that controls the speed of the motor.

The motor is used to both power and maneuver the boat. To steer an outboard you need to move the entire engine. As opposed to larger outboards, which have a steering wheel, smaller boats frequently use a hand tiller to change the engine’s direction.

Depending on the position of the engines, the electric outboard motor can be divided into the motor under-mounted type (suitable for smaller horsepower electric outboards) and the motor upper-mounted type (suitable for larger horsepower electric outboards).

How does Outboard Motor Work?

You may be wondering why it works in quite disparate results. Let’s go over their work principles and figure out the differences between a petrol outboard motor and an electric outboard motor.

The Petrol Outboard Motor

The petrol and air are mixed by a piston-type internal combustion engine and burned in its cylinder, and the heat released can generate high-temperature and high-pressure gas in the cylinder. The gas expansion pushes the piston to do work, and then the mechanical work is output through the crank connecting rod mechanism, which is converted into the kinetic energy of the boat forward through the mechanical transmission and the propeller. If you own a boat that needs a large engine for gliding, then you may be better served with a classic combustion engine.

The Electric Outboard Motor

The electric outboard motor can use the recycled battery as an energy source, and convert the electric energy into kinetic energy through the electric motor.

When it comes to the electric-powered boat, range anxiety is a common topic. To release and overcome this concern, ePropulsion pioneered the use of hydrogeneration in electric outboard engines. Hydrogenators can empower sailors too. Navy 3.0 / 6.0 Evo allows you to collect electricity from wind and water with a hydrogeneration function. It can provide propulsion for aluminum fishing boats, dinghies, daysailers and cruising sailboats, suitable for saltwater and freshwater.

Navy 3.0 / 6.0 Evo | Hydrogenerator Empowers Sailors | Electric Outboard Motor
  • The hydrogeneration data is based on real tests with the anti-ventilation plate installed.
  • Navy 6.0 Evo is tested with a 12.6″ x 8.7″ three-blade aluminium propeller that you could order separately.

Based on its components and work principles, we can easily find out that a boat equipped with an electric outboard motor is emission-free, no unpleasant smells, mostly maintenance-free, amazingly silent, no fear of petrol driving bans on the water, and doesn’t scare off the wildlife.

When we go on a boat trip to enjoy nature and relax, an electric outboard motor is just the perfect thing for you! Besides, the operating costs are significantly lower, which can be an economic advantage for frequent drivers.

Electric outboard motors are very appealing alternatives to petrol motors, especially for small engines. If you want to find your electric motor, our dealer will help you.

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