Electric boats- a comprehensive guide [updated for 2024]
Until recently, petrol and diesel outboard motors have been the default choice for the vast majority of powered boat buyers. But over recent years, due to mounting environmental concerns and rapid technological advances, electric boats have become a viable alternative to petrol and diesel outboard motors. However, with the introduction of numerous electric boat options on the market, many boat buyers may be left wondering which option to invest their money in. In this guide we cover an introduction to electric boats, compare electric boats to petrol and diesel outboard motors, and address key areas boat buyers should consider:
What is an electric boat?
An electric boat is any boat powered by electricity, as opposed to fossil fuels such as petrol or diesel. Electric boats are differentiated by electricity source, boat type, and type of propulsion.
Electricity source
To power the electric motor, an electric boat can use solar panels, generators, connected wires (used in the case of trolley boats), hydrogeneration, or on-board battery packs. Batteries are becoming the most common source of electric power for boats, similar to their use in EVs in the automotive industry.
Boat type
The most popular types of electric boats are small watercraft such as RIBS, tenders, pontoon boats, and local sail and fishing boats due to the shorter ranges required, the practicality of charging, and the smaller and lighter battery packs required compared to larger craft. However, there are also plenty of larger boats powered by electric propulsion including cruising yachts, powerboats and even commercial craft such as ferries and submarines.
Propulsion type
Electric boats are either propelled by a water jet, outboard, inboard, a sterndrive, or with surface or pod drives.
Who is an electric boat for?
Electric boats are ideal for anyone wanting a boat which has zero combustible emissions, faster acceleration and instant power, and a better ride experience from no noxious fumes and no obnoxious noise on the water.
In addition, electric boat owners are typically those who are:
Excited by innovation and enjoy having the newest toys, especially when it comes to playing on their favourite playground—the water.
Wanting to balance having as much fun as they can in the short term while protecting the planet so their family can thrive for years to come.
Looking for a versatile boat that can be used to fish in the harbour, for watersports/diving/swimming, and to explore and adventure in otherwise restricted locations.
Happy to pay a higher up-front price for no ongoing petrol or diesel costs, and fewer maintenance costs.
How does an electric boat work?
A battery-powered electric boat is powered by an electric motor connected to batteries, and has six defining components:
Charger: Transfers the electrical energy from the electricity source to the battery bank, replacing the need for traditional fuel.
Battery bank: Stores the electric energy inside the boat. Capacity and type are important factors in determining the range, performance and safety of an electric boat.
Charge controller: Regulates amps and voltage during the transfer of electricity to the battery according to the battery’s specification before sending it safely to the battery bank.
Motor controller: Coordinates the speed, torque, and direction of the motor.
Electric motor: Converts electrical energy from the battery into mechanical energy to power the propulsion.
Propulsion unit: Moves the boat through the water using mechanical power transmitted from the electric motor.
Electric boats have simple yet clever engineering, requiring no transmission, traditional fuel system, engine blocks, cylinder heads, pistons, valves, or shift mechanisms. This means far fewer moving parts than petrol and diesel outboards, which is the reason for their higher reliability, lower maintenance and longer lifetime.
Why is there an electric boating revolution?
Due to clear environmental reasons and political pressure, the demand for alternatives to petrol and diesel-powered outboards is booming.
The electric boat industry is growing rapidly and boat builders are seeking to obtain as much share as possible of the emerging market by using the best systems for their vessels. This includes more powerful motors, safer and longer-lasting batteries, and the latest chargers.
With the switch to electric boating, buyers no longer need to choose between sustainability and performance. Electric boats have become a proven and compelling alternative to petrol and diesel outboards, and this is predicted to continue with the following trends:
As the electric boat industry increases in scale, the price of batteries and systems will keep decreasing so suppliers and boat builders will be able to offer electric boats across a full range of price points.
Petrol and diesel outboard motors will be denied access to more waterways due to noise and emission pollution, making them a less compelling purchase over time.
Innovation and support will slow for petrol and diesel outboards and these will likely get more expensive to own due to CO2 taxes, while on the other hand electricity is predicted to become cheaper over time.
It is estimated that electric boats represent just 2% of the recreational watercraft market, but volumes are increasing sharply and forecasted to accelerate over the next few years. In fact, the adoption of electric boating is expected to be faster than that of EVs because battery and charging innovations already exist—and are improving at pace. The global electric boat market is projected to reach $16.6 billion by 2031.
Electric boats compared to petrol and diesel-powered outboards
There are a number of key areas for boat buyers to consider when assessing electric boats. Here are some key aspects to assess against a traditional combustion petrol or diesel outboard.
Ownership costs
While electric boats are more expensive to purchase upfront compared to an equivalent petrol or diesel outboard-powered craft, boat buyers should take a total cost of ownership approach to include all costs over the lifetime of the boat for a more accurate comparison.
Usage costs
The cost savings when owning an electric boat compared to petrol and diesel-powered outboards can be significant. For example, petrol can cost NZ$2.50 per litre, compared to the equivalent cost of charging an electric boat battery of NZ$0.30 per litre when charging at home. So a 5 hour day trip on the boat (which uses approx 100 L of petrol) alone will save up to NZ$250. In addition, there are no annoying visits to a petrol station needed to refuel on a busy morning!
Maintenance costs
Compared to petrol and diesel-powered boats, electric boats have lower maintenance requirements, saving owners significant time and effort including:
No engine or foot oils to be changed.
No oil filters, transmission, fuel system, drive-belt, spark plug, petrol lines or distributor caps to check and service.
No need to carry spare fuel on board.
Electric boats still require some care as they operate in harsh marine environments, but this is significantly less than for petrol or diesel outboards. For example, electric boat suppliers recommend that after every 20 hours of usage, water filter and coolant levels should be checked, and after 50 hours of usage, connections and cables should be checked and anti-corrosion and dielectric grease applied. Additionally when unused for more than 1 month, batteries must be charged or discharged to 80% of their State Of Charge.
Replacement costs
As electric boat motors have far fewer moving parts, they are also more reliable and have a longer average lifetime compared to petrol and diesel-powered outboards. A brushless DC electric motor for example can last tens of thousands of hours whereas the average lifetime of diesel outboards is 5,000 hours and just 1,500 hours for petrol outboards.
Electric boats compared to outboard motors: Ride experience
Electric boats deliver a superior ride experience on the water when compared to petrol and diesel-powered outboards for various reasons:
No obnoxious noise so you’ll be able to hear the sounds of nature and have conversations with your passengers. Electric motors are practically silent—averaging a volume of just 30-60 decibels.
No noxious fumes so all you smell is the clean ocean air.
No slow or false starts. Electric boats start instantly, every time.
Less vibration due to fewer moving parts.
More consistent speeds and easier maneuverability due to instant torque.
Instant power and acceleration due to instant torque.
Electric boats compared to outboard motors: Environmental impact
Electric boats have less of an impact on the environment as they produce zero direct emissions (emissions during use)—reducing water and air pollution by eliminating the greenhouse gasses and the range of water and air toxins produced by petrol and diesel-powered boats such as carbon dioxide (CO2), nitrogen oxides (NOx), hydrocarbon (HC) and volatile organic compounds (VOC).
The production of electric batteries does however produce emissions, leaving the question of whether electric boats do in fact have less overall negative impact on the environment than petrol or diesel-powered outboards? The below evaluation provides a breakdown comparison:
The cost to produce lithium based batteries is around 73 kg CO2-equivalent/kWh:
Energy used during the manufacturing process (20% of total)
Mining and smelting of aluminum for the battery packs themselves (17% of total)
Mining, refining and converting the active materials including lithium (40% of total)
But while it takes more emissions to produce an electric boat compared to a petrol or diesel-powered boat, the zero direct emissions quickly makes up for this. For example, production of a 10 kW electric battery produces around 730 kg of carbon emissions once, while a comparative petrol or diesel-powered engine produces 5,000+ kg during use every single year. The quick pay-off of electric boats compared to petrol and diesel-powered boats is further evidenced in this comparative analysis of EVs, showing that despite the production of an electric battery, electric vehicles have less impact on the environment in as soon as 4 months.
Below are some additional factors to consider when assessing the impact on the environment:
Petrol and diesel outboard motors have disproportionate emissions
It requires greater proportionate power to move a boat through water than to move a car on land, so outboard motors burn a lot of fuel compared to many cars. Additionally, the automotive industry uses methods such as exhaust gas recirculation and catalytic converters to reduce pollutants, but petrol and diesel-powered outboards don’t have comparable systems. This is why the level of harmful nitrogen oxide and hydrocarbon emissions is much higher with outboards than cars. In fact, although emissions vary by type of outboard motor, one study showed that even a ‘clean’ boat engine produces the same pollution as about 50 cars operating at a similar speed. And a not so clean engine? Around 10 times more than that!
Drilling for oil is generally worse for the world’s ecosystem than mining for lithium
Drilling for oil can occur in highly biodiverse areas, where large amounts of carbon are introduced into the atmosphere from deep in the earth’s soil during the process, while lithium is extracted from desert salt flats which can be in more isolated places. Additionally millions of litres of oil are spilt every year during the transportation process around the world.
The impact of mining for active materials will reduce over time
For a variety of technical, economic and environmental reasons, leading electric boat companies are now exclusively using LifePO4 (lithium-iron phosphate) batteries which do not contain cobalt or nickel. Plus, innovation is uncovering ways to reduce the emissions from mining for the lithium itself. For example Vulcan Energy has pioneered an extraction technique for lithium using geothermal power which claims to emit no CO2.
Electricity sources for batteries will get cleaner over time
Many batteries are currently manufactured in countries where the mix of energy is not so clean. But, as these countries move away from using coal and natural gas to renewable sources like wind, solar and hydro energy, battery production emissions will reduce. Even so, studies have shown that there is already no single state in America where petrol or diesel-powered boats are better for the environment compared to petrol and diesel outboards regardless of electricity source (there are however a few states where hybrids are currently better than electric due to their energy mix).
Electric boats vs outboards: Performance
While it is true that electric boats are typically less ‘powerful’ than petrol and diesel-powered outboards, many electric boats on the market today do not match the stereotype of being ‘slow, boring, and unable to bring a boat up to planing speed’.
Some electric solutions do lack in performance, but there are plenty of exceptions. For example, the ZeroJet-powered OC Tender can speed up to 20 knots, quickly gets to planing speed of 10 knots and due to its jet-drive, delivers an exhilarating on-water experience. Plus, some electric boats can hit speeds of up to 109 mph!
Choose the right electric boat and you can not only have a functional boat ideal for your daily needs, but an exhilarating water toy fun for every yachtie and his or her family!
Electric boats vs outboards: Range
Electric boat ranges vary by factors such as boat type, weight, battery size, speed, load, and sea-state. While there are larger, luxury electric boats that can have you speeding out to sea for the whole day and back on a single charge, the average electric boat does deliver less range and runtime on a single charge compared to petrol and diesel-powered outboards with a full tank.
However, given the intended use for smaller electric boats is typically for shorter trips and leisure activities, this shorter range and runtime does not mean the average electric boat is impractical:
There’s enough range and runtime for inner harbour fishing, morning watersports, or to use as a tender to transport your family and friends to and from your yacht during the day.
They can be easily charged in-between uses with an average charge from 20-99% for 10Kwh battery packs of 4 hours using a 40A charger and 2.5 hours using a 65A charger.
There’s easy access to charging sources as electric boats can be charged using standard AC power, so they can be charged at home or on the mothership in-between uses, as well as at marina berths.
To further ease range anxiety, boaties should ensure they purchase a boat with a sophisticated battery management system which will accurately display the remaining range and runtime to ensure they’re never caught short.
Electric boats vs outboards: Safety and durability
One common concern boat buyers have when considering purchasing an electric boat is reflected in the saying ‘electricity and water do not mix’. The worry is that electric boats are not a suitable solution in the marine environment because of durability and safety risks such as electrocution, fire and faults in the motor.
But the truth here is that electric boats pose no additional risk than petrol or diesel-powered outboards. Manufacturers safeguard the boat’s battery system with various measures. For example, the ZeroJet system is protected by custom-built cases to house its battery packs which are shock and impact resistant, strengthened and waterproof. Electric boats are also given an IP rating dictated by the international standard called the IP code which indicates how well the batteries are protected against water—as well as dust, accidental contact and intrusion.
The chemistry of the battery used in the electric boat is also an important consideration. Lithium Iron Phosphate (LiFePO4) batteries are the safest battery chemistry on the market as they are incombustible so don’t catch fire like commonly used lithium-ion batteries can. If you subject a LiFePO4 battery to harsh temperatures or hazardous events (like short circuiting or a crash) it won’t start a fire or explode.
Why you should choose an electric boat over a petrol or diesel outboard motor
If you are in the market to buy a new boat and able to afford the higher up-front price of an electric boat, the benefits quickly outweigh the cost, and become even greater over time.
Electric boats have lower maintenance, are more reliable, have a longer average lifetime and can save you up to NZ$50 per hour out on the water.
Electric boats deliver a more enjoyable ride with no obnoxious noise, noxious fumes and are overall smoother to drive.
Electric boats are significantly better for the environment, even when taking into account the emissions produced during the production of the electric batteries.
While electric boats are typically less ‘powerful’ than petrol and diesel-powered outboards, there are electric boats on the market that not only deliver the benefits of electric but also an exhilarating on-water experience!
While electric boats have less range compared to petrol and diesel-powered outboards, this doesn’t make them impractical given their intended use. They’re fit for purpose, quick and easy to charge, plus many have sophisticated battery monitoring systems that accurately display remaining runtime so you’re never caught short.
Electric boats must undergo rigorous testing and meet required certifications before making it to market. They pose no additional safety or fault risk than petrol or diesel-powered outboards in the marine environment.
Petrol and diesel-powered outboards will continue to be denied access to more areas, innovation and support for them will slow, and petrol and diesel will likely get even more expensive.
Thanks to rapid innovation in the emerging electric boat industry, you can have it all with electric boats. When looking to invest in an electric boat, make sure to get the best value for money by researching how options compare in terms of total cost of ownership, range and runtime, safety, manoeuvrability, practicality and FUN!
In part 2 of this series (Electric jet boat motor or electric outboard motor- which is best?) we cover more details on electric jet motors and electric outboard motors and in part 3 provide a Buyer's Guide to electric boats. There are also many reviews of electric boats including this one by Gone with the Wynns in which they test the “5 best electric boat motors” on the market.
ZeroJet is a pioneer of zero-compromise boating and manufacturer of electric jet propulsion systems, powering a range of electric tenders and RIBS across the globe. The ZeroJet Gen2 system has achieved sustainability, safety, practicality, and performance in one compact package, making it a world-leading marine propulsion system.
About the author:
This article was written by Stephanie Kingsford in collaboration with ZeroJet’s team of electric boat and electric jet system experts. Steph is a strategic communications specialist with a decade of experience advising and collaborating with companies on sales, marketing and communications. She and her family are based in the wonderful Waikato region of New Zealand.