Electric vs. combustion - are electric boat engines worthwhile?

  • 1. What are the advantages and disadvantages of electric motors and combustion engines for you?
  • 2. Similarities between electric and combustion engines
  • 3. Differences between electric and combustion engines
  • 4. The disadvantages of an electric motor

What are the advantages and disadvantages of electric motors and combustion engines for you?

We give you a brief overview of the similarities and differences between electric boat engines and internal combustion engines. What are the advantages of the electric motor on the boat? We hope you enjoy reading! Please write to us with your questions and suggestions about the article.

Similarities between electric and combustion engines

Speed of electric motors and combustion engines?

Can I drive as fast with an electric motor as with my combustion engine or am I slower on the road?

Do not worry! An electric motor also provides excellent support for your boat. At maximum speed, the two motor types are therefore on the same level.

What does the speed of the boat depend on?

In the beginning, we thought that only the engine is decisive for the speed. However, the speed depends on your boat rather than the engine. In our article Everything about your boat we tell you more about the economic speed and which values are necessary to calculate the speed.

Energy consumption of the electric motor and combustion engine on the boat?

This relationship is also constant! ! Important: The faster you drive, the more energy you use. No matter whether with electricity, petrol or diesel. And that exponentially in the third power! What does that mean? If you want to double the speed, you need eight (!) Times as much energy as before.

We, therefore, recommend traveling at a gentler speed regardless of the engine. Of course, you can crank it up! However, you should always have enough battery capacity or additional fuel onboard so that you don't stay dry!

So the decisive factor is not the energy consumption, but rather the type of storage onboard and there are differences here. You can read more about the differences in the range below in the article.

How the electric motor and combustion engine work

Technically, the electric motor and combustion engine is of course fundamentally different. You can read more about this in our article on how boat engines work. Rather, it is about the purpose that both engines pursue.

The propeller converts the engine's power into thrust and pushes the boat in the desired direction. Combustion and electric motors have a common purpose and ensure maximum driving pleasure on the boat trip. The design and how the drive shaft is rotated works differently.

Installation of the boat engines

The installation of the engine on your boat looks the same in any case. An electric outboard is mounted just like a petrol outboard. The same applies, of course, to the other engine types, regardless of whether flange engine, inboard or sail drive. If you have specific questions about installation, take a look at our article on the various electric motors.

Differences between electric and combustion engines

Is an electric boat motor worthwhile for my boat?

What are the advantages and disadvantages now? The most important question for boat owners: What is better for me and my boat? To make the comparison easier for you, we will show you the advantages and disadvantages from the perspective of the electric motor.

The advantages of an electric motor in boats

The advantages of the electric motor compared to vehicles with an internal combustion engine are many. In our view, the electric motor has many advantages, but it is not always 100% suitable. There are also some challenges that electric motors pose. We will show you how you can easily eliminate these supposed disadvantages with our help.

  • Electric motors are significantly quieter or completely silent

  • Emission-free, no unpleasant smell

  • Running costs significantly cheaper!

  • Environmentally friendly and ecologically sustainable

  • Future-proof: No fear of driving bans on the water

  • Maintenance-free: less effort

  • Greater safety on board

  • Efficiency and acceleration are higher

  • Handling and operation are easier

  • High flexibility: electricity onboard and in port

1. The volume of an electric motor

An electric motor is significantly quieter than an internal combustion engine! The volume of the engine varies depending on the type and structure. Electric motors without gears have a volume of only 30-60 decibels and are practically silent. Electric boat motors with gears, on the other hand, are somewhat louder, around 70 dB.

In any case, electric drives are significantly quieter. The noise of an internal combustion engine is reminiscent of the main streets in a big city. For us, that was exactly the reason to think about an electric motor for our boat. When we go on a boat trip, we mainly think of nature and relaxation.

Our opinion: There is no alternative to electric motors when it comes to volume ... apart from muscle strength, of course, here you are even doing something good for your health!

2. Emission-free and a clean affair

An electric motor produces no polluting and stinking exhaust fumes when driving. Studies have shown that 38 times more nitrogen oxides are released into the atmosphere due to the lack of filter systems. In addition, the engine does not need an oil that could leak.

Do you go out on the lake with the family and smell a gas station? For us personally, this was one of the most important reasons to deal with the topic of electromobility. (Of course, there are exceptions that like the smell of a gas station.) Nevertheless, we think of you and your health.

Missing exhaust gases or lubricants in the water also have a major impact on animals and the environment. Too often in port facilities, we see a shimmering oil film on the water. In addition to the animals, it also has advantages for the water quality in your area. Especially with the hotter summers, the water quality of the lakes and rivers in Germany is an important factor, which is favored by electric boat drives.

3. No maintenance costs and cheap operation!

An electric motor is considerably cheaper in the long term. You are spared maintenance costs and you only need electricity as an energy source. Depending on the motor, especially in the low power range, electric motors can be cheaper from the outset than combustion engines.

The larger the battery, the higher the cost of the complete system. When purchasing, we recommend paying close attention to how much capacity you need on average.

We have developed a small cost calculator for you on our website. You can conveniently compare the annual costs from home and see when an electric motor is worthwhile for your boat.

You just have to state how often you drive each year and how much your boat uses. Another interesting point: you can see how much CO2 the boat engine emits over time and how much CO2 can be saved.

Amortization: when is an electric motor cheaper?

The payback period depends on the engine and your driving behavior. In the calculation, you compare the costs of the purchase with those of the operation: You buy a 15 HP internal combustion engine for € 4000 and spend € 800 annually for petrol and € 200 for maintenance. Or you can buy an 11kw (15hp) electric motor with a battery system for € 8,000 and only spend € 200 on electricity per year.

Your electric drive pays for itself after only 5 years. After 10 years, you have already saved € 4,000. Fossil fuels are a limited resource. Do you think the price will go up in the future? In the long term, we assume that gasoline prices per liter will increase significantly due to a CO2 tax or similar.

On the other hand, inexpensive solar cells offer the opportunity to generate electricity for free. This electricity can be stored directly in your battery system.

4. Environmentally friendly and ecologically sustainable

If you use green electricity for your electric motor, the operation is even climate-neutral. What does climate-neutral mean? There are no harmful CO2 emissions or nitrogen oxides that pollute the air and endanger your health. In addition, pollutants such as fuel, oil or other lubricants do not get into the water. With electric motors, there is no danger to endanger the local waters and animals.

In order to generate electricity on the water itself, it is possible to mount solar modules or small wind turbines on the boat. Alternatively, you can also set up systems at the jetty or on your boathouse and are also safe from rising electricity prices.

This is particularly suitable for houseboats with a larger roof area, but also for smaller boats. Many solar modules are collapsible or can be rolled up and are therefore easily installed on the roof or the railing of the boat.

5. No driving bans for electric boats

There is a lot of news in the news about car exhaust and thought about driving bans. This topic is also becoming more popular on the water - from 2025 onwards, boats with internal combustion engines will no longer be permitted in Amsterdam. Filter systems for cleaning the emissions are missing from boat engines. Boat engines generate 38 times more dangerous nitrogen oxides than cars.

Of course, there are already a large number of lakes with driving bans in Germany and Austria. We personally are sure that driving bans and higher circulation will increase significantly in the future. With an electric motor, you are on the safe side here. Especially when you are thinking about buying a new boat engine, you should keep an eye on this, not an insignificant factor.

6. Maintenance-free - never stress again!

In the middle of the season, you have to have your engine replace wear parts. Not with an electric motor. Most electric motors are maintenance-free and have an extremely long service life with high-quality workmanship. As a result, you are spared a lot of stress. Does the engine still have a guarantee? Where can I get the engine repaired and how much will the fun be?

Maybe you are also technically well-versed and the replacement of a few wearing parts does not pose any problems for you. Then that's not so dramatic for you. We would be completely overwhelmed, to be honest! Therefore we prefer to play it safe with an electric motor.

7. Higher safety on board

Safety is the be-all and end-all. On the road, e-cars impress with their greater safety. On the water, the battery must be stored in a dry place, splashing water is not a problem. Most motors are absolutely splash-proof. Some batteries are even completely floatable.

The risk of fire is low, but we still recommend a special fire extinguisher onboard for certain batteries. We mainly work with lithium iron phosphate batteries. These are not flammable and therefore absolutely safe.

Fiddling with flammable and explosive gasoline on board is no longer necessary. In our view, it is much more pleasant without gas can onboard.

8. Better efficiency and higher acceleration

An electric motor has significantly higher efficiencies: The energy conversion is very efficient because no-idling speed is required. This means that there is already a very high torque from the first revolution, which is why electric motors can also achieve a significantly higher acceleration.

In practice, this certainly sounds understandable: the faster it starts, the better for you. The same can be seen with electric cars. It's not for nothing that a Tesla Model S has such high acceleration and leaves all other cars behind at the traffic lights. And that despite the additional weight of the batteries!

9. Simple operation and good handling

Operation and handling are easier than with an internal combustion engine. Gasoline engines are usually started with choke, you have to "start" the engine, so to speak. And that often doesn't work the first time. With an electric motor, you start the engine directly at the push of a button.

Many engines have a speed control for stepless control. The advantage is that the motor can switch between driving forwards and backward without switching. Operation is much more intuitive, user-friendly and the speed can be regulated better.

Another advantage of electric motors is that the motor and battery can be monitored very easily. Manufacturers often offer special functions that are not directly integrated into internal combustion engines.

This includes calculating the remaining range, power consumption, GPS, or on autopilot. Of course, you could also add these features to internal combustion engines if you wish. They are often already integrated into electric motors and you do not have to invest more money than necessary.

10. High flexibility: electricity anytime, anywhere

When you use an electric motor, you always have electricity on board. Other electricity consumers such as heaters, lamps, cool boxes and others can be operated via the same circuit.

Pay attention to the required capacity early on when designing your batteries. When planning the route of your boat trip, you should also consider loading points due to the maximum capacity.

The good thing about electric motors: electricity is available almost everywhere! So you can recharge the battery on your own dock as well as in ports, jetties or at charging stations and are therefore very flexible.

The disadvantages of an electric motor

Are boats suitable for an electric drive?

Skepticism about electric motors is still high. We want to remove prejudices and show you the advantages. Internal combustion engines have worked well for decades. However, electric motors are technically much more efficient and the only real disadvantage at the moment is the energy supply. Electric motors require electricity and a rechargeable battery usually serves as the voltage source on the boat.

  • Energy density and range

  • Acquisition costs of electric boat engines

  • Environmental impact of battery production

  • The weight of boat batteries

  • Charging time for electric boat engines

1. Energy density and range

Petrol has an energy density that is 100 times higher than that of lithium-ion batteries. Electric motors are 10 times more efficient for this. Effectively, the energy density is 10 times worse and therefore has a negative effect on the maximum range.

Therefore, battery weight and purchase costs are an important aspect, especially for larger engines or permanent gliding. It is, therefore, worthwhile to determine the battery capacity optimally based on the desired travel time and capacity.

By planning your routes or excursions well, this disadvantage can be easily avoided. Electricity is usually available at every jetty or port. If you use your boat during the day, it can be connected to the power supply at the dock overnight and is fully operational again the next day at the latest.

While it is a disadvantage, you either need more battery space in your boat or have less range. Fortunately, an electric motor takes up significantly less space than the main engine with an internal combustion engine. In our experience, there have been no problems with the range for most of the changes to an electric motor.

2. Acquisition costs of electric boat engines

The acquisition costs for the battery increase with the required capacity. They make up a large part of the total cost of an electric drive system. An electric motor is definitely worthwhile for small and medium-sized motors. The costs are not much higher or even lower compared to the combustion engine.

In the past decades, there have been huge leaps in the energy density of batteries, at 5 to 8 percent per year. Many billions of euros are invested annually to drive development forward. The main players are, above all, the large automobile manufacturers, most of whom are planning to switch to clean energies by 2030.

Boat owners in particular benefit from this and the concept of electric motor and battery becomes more attractive. Battery prices are currently falling from € 1,000 per kilowatt-hour to only € 500. This development will be cheaper in the next few years and significantly more profitable for you! In addition to new types of batteries, a lot of research is being done on the use of hydrogen as an energy source. Hydrogen promises a similar range and quick refueling as with normal fuel.

However, the cost of the fuel cell is currently not yet competitive. We remain excited and will be at the forefront! And more importantly, we keep you up to date in our newsletter!

3. Environmental impact of battery production

Electric motors and battery systems have to be manufactured and transported to Germany. Resources are also used in production and CO2 emissions are incurred. The engines will also mostly be produced in Asia and then imported.

We attach great importance to this fact and prefer manufacturers with a better carbon footprint. We have designed a special CO2 calculator on our website, with which you can calculate the CO2 balance in detail and see when an electric motor is better for the environment.

Because of the electric cars, there is a lot of media coverage about the manufacture of batteries and the resulting damage to the environment. A detailed article on production and the associated emissions will follow shortly.

Around 125 kg of CO2 is generated per kWh battery. This corresponds to the emission of around 60 liters of petrol. Depending on the size of the battery, you can quickly calculate the consumption after which the changeover to a battery-electric vehicle is worthwhile. Usually within the first year!

4. The weight of boat batteries

Larger lead battery systems are very heavy or very expensive for lithium. The purchase of lithium batteries only really makes sense for frequent drivers. You are a frequent driver from around 40 trips a year when the battery is completely discharged. However, as an occasional driver with AGM and gel batteries, you also enjoy all the advantages of an electric motor that cannot be weighed out with money alone.

As a rule of thumb, AGM batteries are about three times heavier. Usually, the tank flies out of the boat during a retrofit and provides enough space and a certain frame for additional weight on the boat. It is important to design the battery as optimally as possible, then a little more weight in the boat is almost no more disadvantage. Especially with sailing boats, they sometimes need a little more weight in the keel.

5. Charging time for electric boat engines

The charging time until fully charged varies depending on the battery and charger. A boat can be filled with petrol, diesel or hydrogen much faster. On paper, this is another disadvantage of an electric boat drive. However, boaters are very rarely on the road for long periods without a stop.

The charging speed of battery systems continues to increase and the flexibility of e-mobility continues to develop. The Supercharger from Tesla leads the way and charges a car battery up to 80% within 30 minutes. The number of charging stations on the water also continues to increase, making longer excursions possible in the future without any problems.

Depending on your needs, we will be happy to find a suitable charging option for your boat or an electric drive with the appropriate range. However, an electric motor is not useful for every range and every application.

Conclusion: comparison of electric and combustion engines

Both variants have their advantages. If you want to drive your boat silently across the lake, want to protect the environment and your local waters or love progress, an electric motor is just the perfect thing for you! With small and medium-sized motors, in particular, almost everything speaks for electromobility.

If you own a boat that needs a large engine for gliding, then you may be better served with a classic combustion engine. Mainly because of the battery system.

The arguments for combustion engines are, above all, the sometimes lower acquisition costs for larger drive systems and the longer range and travel time for large engines. In this area, electric motors are in the absolute premium segment, because everything is possible. Battery systems for sliding boats are particularly expensive. Nevertheless, electric motors are also ideal for gliding and have just as much power! Especially for lakes where only e-boats are allowed, there is no alternative.

The advantages of an electric motor are that it is quiet, emission-free, clean and mostly maintenance-free. Besides, the operating costs are significantly lower, which can be an economic advantage for frequent drivers. Electric motors have also been very popular with anglers, small boats, and inflatable boats for many years.

The price with a battery is often even lower or at least as high as for a combustion engine. The countless other advantages of the electric motor outweigh here. We are excited to see how the topic of e-mobility develops in Germany and Europe and look forward to your feedback and your experience with e-motors!

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