How to choose an electric motor for a boat?

Wide selection and challenges

In recent years, "greening" and electrification of the entire industry has already become a trend. As a result, today you can find dozens of offers on the market - there are electric motors for every taste and color. 

Modern electric motors are versatile and affordable. The variety of drives and powers can be daunting, but much more important is a simple question to ask yourself before upgrading your boat: “Am I right for an electric motor?” 

Usually re-equipping an engine is not a cheap undertaking - replacing a diesel engine with an electric motor will be equivalent to a decent amount of fuel. Saving money on fuel is certainly a good reason, but it shouldn't be the only one. Most often, yachtsmen are guided by the following reasons for replacing the engine:

– reduction of the noise level on board;

- in the long run, the electric motor will be more profitable;

– absence of exhaust gases;

- "greening" of the industry and the desire to join the rescue of the environment;

– use of renewable energy sources; 

- access to closed water areas and places where it is forbidden to drive under a diesel engine. 

If you go to sea once every few months for a couple of days, and the rest of the time the boat is idle, then you are unlikely to be able to save on fuel if you install a new engine. The electric motor should be viewed as a long-term investment in the boat and should not be expected to have any immediate effect.

Also, do not forget that batteries for an electric motor will cost more than combustible fuel. Lithium-ion batteries, like their derivatives, are quite expensive, but are the most efficient. However, with proper care, any battery will last a long time and reliably. In any case, the choice is yours!

Which engine to choose?

When choosing an engine, it will be easiest to build on what is already installed on your boat. Any already used motor can be replaced with an electric counterpart. 

An excellent option would be to replace the engine, which takes up valuable space on board. Instead of a bulky diesel engine, you can install a compact electric saildrive - a very popular solution today. In addition, this is a relatively simple modification that will not require major changes to the design of the boat.

If you have a small boat and only an outboard motor is installed, then you should look for an electric motor that is comparable in power and dimensions. 

What motor power is required?

The standard conversion from horsepower to kilowatts is to multiply diesel power by 1.359. Thus, we get that 5 kW of electric motor power will be equivalent to 6.7 hp. Usually, the indicators differ slightly depending on the model and manufacturer.

However, an electric drive will most often indeed be more powerful than a diesel one. Keep this in mind when choosing an engine. Another feature of electric motors is that they can produce sustained thrust even at not very high RPMs. Thanks to this feature, a larger propeller can be installed.

In addition, unlike diesel and other internal combustion engines, electric motors are not so strongly affected by the environment and external factors. They are less susceptible to temperature changes, humidity, and the quality of the fuel does not concern them at all. Electric motors also boast a smoother torque curve. These features make electric motors more efficient over the entire available speed range. 

What type of battery should you choose?

When it comes to inland travel in small boats, lead-acid batteries are the traditional option. Not only are they cheap, but they are heavy enough to be used as ballast.

If we are talking about sailing boats, or even more so motor boats, then more serious batteries are needed. Usually yachtsmen use lithium-ion batteries, but it is not uncommon to find cheaper lead-carbon batteries.

Hydro-regeneration and other methods of energy production

An excellent solution for saving energy and increasing the range is hydroregeneration. Many electric motors offer hydroregeneration - even some outboard and relatively inexpensive models. This option will not be redundant.

In addition, in conjunction with solar panels and wind turbines, you can very well replenish the energy supply lost during the cruise. Some types of batteries are built into the side of the boat or even into the sails!

Is it worth it to replace the engine?

Depends on what you expect from your new system. Above, we described a number of reasons why many people are switching to electric motors, but not everyone needs such upgrades.

The new electric motor will also require a different approach to control and operation. Many manufacturers offer convenient monitoring and usage systems. Some models of electric motors are even supplied ready for installation, and all that remains to be done is to install the motor in the right place. Many companies are also creating entire ecosystems for remote monitoring and control of their electric motors. 

If you doubt the merits of electric motors, but diesel does not suit you either, then take a closer look at the option of hybrid installations. Some shipyards immediately offer hybrid versions of their boats.

Don't forget to rate the content! You can find other interesting articles on the links below or in the "News" section!

19.05.2023