What Size Brushless Motor For RC Boat: A Complete Guide

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RC boating is fun, perhaps picking the right size motor is not!

A bigger boat will require bigger motors. Yes, it’s obvious. However, it’s crucial to know which motor works perfectly with any particular size of boat. Any wrong pick can end up in disoriented movement or even drowning of the boat.

So, the obvious question from your end will be what size brushless motor for the RC boat?

A 28-29mm brushless motor would work with a 600mm boat hull size. On the other hand, a 40mm brushless motor would work with a 1200mm bolt. For anything over 1200mm boat hull size, a 56-58mm motor is suitable. As an RC boat running enthusiast, you must pick up the right size for you. 

Now, this is a quick preview of what size RC boat suits the right motor. We shall go deeper into the RC boat sizes and recommend the right products for you. 

RC Brushless Motor Size Chart For Your Boat

Here, we are looking into RC boat brushless motor size with respect to RC boat size.

Brushless Motor Can Size RC Boat Hull 
28-29mm 600mm
36mm 800mm
40mm 1200mm
56-58mm Anything over 1200mm

The comparison is done by keeping the motor diameter in check. As we can see, the bigger the boat size, the higher the motor diameter.

Brushless Motor Can Size Revolutions Per Minute (RPM)
28mm 30,000 – 35000
36mm 40,000 – 45000
40mm 35000 – 40,000
58mm 28000 – 30,000

Different sizes of brushless motor have different RPM. RC boats that are smaller in size will not generate RPM more than 35000 RPM. 

Brushless Motor Can Size RPM (At most) Voltage Kv
28mm 35000 20v 1750
36mm 45000 17v 2647
40mm 40000 12v 2916
58mm 30000 15v 2000

Here we have calculated the Kv rating, keeping the battery voltage in check.
So, we need to find out the size of your RC boat. Also, how it is functioning in terms of RPM and KV ratings. To test the functions of the brushless motor, you can use a multimeter with the brushless motor.

Using the electric boat motor calculator,  we can determine the performance of the motor. 

For example, we can calculate that KV = RPM/V

With this equation, we have calculated the kv for four different sizes of RC boats. It is good that you know the voltage and kv for the different motor sizes. This helps to buy the right batteries for your RC boat.

600mm hull RC Boat 

A 600mm hull RC boat would suit a 28mm brushless motor. As the chart suggests, a 28mm RC boat motor can generate 1750kv (KV = 35000/20). So you must go for a brand that is offering this kv rating.
The brand Traxxas is providing products for 600mm RC boats. But you can also look at other brands Crazepony and Tamiya. They are performing at the top level as the best brushless motor brands

The brand Traxxas are providing products for all sizes and speeds. But you may want to look at other brands. You may want to compare Traxxas hoss and maxx together to check which is better.

For example, if you are having a DIY RC boat setup, BETAFPV can be good for you. It is very durable and lightweight. It further comes with the 3s Lipo battery.

800mm hull RC Boat

For an RC boat that possesses an 800mm size, you will need a 36mm brushless motor. This can size is generating an RPM of 40,000 to 45000. 

The brand, Volantex is good for this size. They are available with 1750 to 3000kv powerful brushless motors. 

RC boat racing is more fun when you have the right brand. Volantex should be your right brand as it offers a 45mph+ speed.

Speed however depends on if the motor is censored or sensorless. If you are looking for more speed, brushless motors should be sensorless

If you want more fun, add the RC boat electric conversion kit. This helps with better speed and performance.

Products like 12HP Burst Power and 15HP Burst Mode are good for 800mm RC boats.

800mm RC boats need a 17voltage battery. In this case, you can buy a 5 cells x 3.7V= 5S battery. 

1200mm hull RC Boat

1200mm RC boats are big. A 40mm brushless motor is good for an RC boat of this size. With this size, the RPM is 35000 to 40000.

The bigger size comes with more fun as it shows more resistance to water. A 40mm brushless motor is more energy efficient. 

The Maxon 40mm brushless motor is more common in the market. The product weighs around 203 grams and provides high power density. A right-weight motor is good for overall RV boat performance. 

1200mm RC boats need a 17voltage battery. In this case, you can buy a 4 cells x 3.7V= 4S battery.

Installing a brand new brushless motor is an easy task. However, it is good to set up your RC boat with some supporting kits. They are there for your RC boat’s safety and durability.

Products like the ZTW Seal Series do a fair job of supporting your motor. It offers a smooth operation for a voltage of 5 to 24. So, it fits all the RC boat hull sizes.

Furthermore, add a ZTW series programming card that would give you exact numbers. With this, you will be aware of your boat’s performance and know when to change kits. 

They come very cheaply while ensuring cost-effectiveness. This is because you may not know how your boat is functioning. You may have to spend extra on buying accessories more often.

1200mm+ hull RC Boat

Bigger RC boats perform better. You are perhaps building an RC Boat that is more than 1200mm. For that, you will need a brushless motor that is around 56 to 58mm in size.

As mentioned before, a bigger size generates better output. With its bigger size, a bigger RC boat would show better air resistance. This would be a more fun experience for you.

This is the reason why many RC boat lovers go DIY. They build their own RC boat, sometimes larger than the market would offer. 

RC boats that are bigger than 1200mm, generally need a 15voltage battery. So, get a 5 cells x 3.7V= 5S battery. 

If you are looking for product recommendations, we have just the right product for you. 

Product 1
Product 2

Many of you are perhaps building a 1500mm bolt. So, you must find a brushless motor that generates around 2000kv. This should ensure a complete performance. 

You can also have an RC boat twin-motor setup. The bigger size RC boat would suit this setup for better speed and performance. 


What if you put the wrong brushless motor size?

Your RC boat won’t function with the wrong motor size. You have to buy the right size brushless motor that supports the hull size. Say, you buy a 36mm brushless motor for an RC boat that needs 40mm. It won’t just simply function!

What is the difference between brushless and brushed motors?

The brushless motors are more powerful than brushed motors. Brushless motors are more electric than brushed motors. Brushed motors are mechanical in nature and so function less efficiently than brushless motors. 

Why do we need conversion kits for brushless motors?

Usually, some conversion kits are recommended for better performance. However, it is not mandatory to buy all the kits. There are other techniques that can be applied for better performance.

For example, having more stable control over the controllers can also ensure better performance. If you are a pro, you may not need extra kits. 


Here we have solved the equation to what size brushless motor for RC boats. Different charts and calculations have given us some important answers. 

With this, you can definitely buy the right products for more fun and amusement. 

If you have any questions, leave your comments below. 

Good luck!

About the author

Travis Murray

I am Travis Murray, and my love for RC began in 2017. It gradually turned into a passion, leading me to become an RC enthusiast and blogger. I write in-depth reviews and DIY guides for RC enthusiasts to provide troubleshooting tips and insider knowledge to help starters find the hidden gems in the hobby.
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