Getting the right Electric Motor and Prop for your narrowboat
The market for narrowboat electric motor systems is expanding, offering a wide array of choices for today’s boat owner. However, when Mothership Marine first ventured into this field in 2016, the landscape was far more limited. This scarcity of options drove us to design and engineer our own comprehensive electric propulsion systems.
The Challenge of Building a Marine-Grade Electric System
At first glance, creating an electric motor system seems straightforward. The core components—a motor, a motor controller, a power source, and a throttle—are all readily available. In fact, many of these are standard in industrial applications, with the battery-operated forklift truck being a prime example.
However, a narrowboat is a far more complex environment than a warehouse floor. Forklift trucks don’t need to power showers, refrigerators, lighting, and entertainment systems, nor do they integrate with generators or solar panels. At Mothership Marine, we have always understood that a truly great boat depends on the seamless integration of all its electrical components.
One of the most significant and often overlooked challenges has been sourcing a high-quality, durable throttle. Electric marine throttles are a niche component, attracting minimal interest from large-scale manufacturers, which makes finding a reliable and robust unit surprisingly difficult.
Why Your Choice of Electric Motor Matters
This article focuses on the heart of the system: the electric motor. Selecting the right type of motor is critical for the efficiency, reliability, and handling of your narrowboat.
While DC motors are an efficient option, they are typically brushed. This design makes them vulnerable to burnout if the propeller becomes fouled or impeded by debris. For this reason, we believe the two most suitable and reliable options for narrowboat propulsion are:
- AC Induction Motor
- PMAC Motor (Permanent Magnet AC Motor)
Each of these motor types offers distinct advantages for marine applications. When paired with a sophisticated controller and a fully integrated electrical system, they provide the quiet, reliable, and powerful performance that defines the modern electric narrowboat experience. Our focus on an integrated approach ensures that your motor works in perfect harmony with your entire onboard power system, delivering an unparalleled experience on the water.
Of the 2 Mothership Marine prefer the PMAC motor. Here’s why.
While both AC Induction and PMAC motors are excellent choices for electric propulsion, at Mothership Marine, we prefer the PMAC motor. Here’s a detailed look at why.
Permanent Magnet AC (PMAC) motors stand out as the superior choice for marine propulsion, primarily due to their exceptional reliability and efficiency.
How Do PMAC Motors Work?
To understand their advantages, it helps to know how they operate. A PMAC motor consists of two key components: the stator and the rotor.
- The Stator: This is the stationary outer part of the motor which contains coils of wire (electromagnets). A motor controller takes DC current from the boat’s battery bank and converts it into a precise 3-phase AC current. When this current energises the stator’s coils, it generates a rotating magnetic field.
- The Rotor: This central part is connected to the propeller shaft and features powerful permanent magnets, often made from rare-earth metals.
The magnetic field from the stator interacts with the permanent magnets on the rotor, causing it to spin with immense precision and force, thereby turning the propeller.
Key Advantages of PMAC Motors for Marine Applications
This elegant design provides several distinct advantages for a narrowboat owner:
- Unmatched Efficiency: PMAC motors are incredibly efficient. Because the rotor and stator interact only through a magnetic field, there is no physical contact or friction to waste energy. The sophisticated AC signal from the controller ensures smooth, continuous rotation, converting more battery power directly into propulsion.
- Exceptional Reliability & Low Maintenance: With no brushes or physical contacts to wear out, PMAC motors are often referred to as “zero maintenance” motors. This simple, robust design leads to outstanding long-term reliability—a crucial factor for any boat owner.
- Whisper-Quiet Operation: The frictionless operation not only boosts efficiency but also makes PMACs one of the quietest motor types available. Enjoy the peace and tranquillity of the waterways without the noise and vibration of a traditional engine.
- High Power Density: For their physical size and weight, PMAC motors produce more power and torque compared to other motor types. This allows for a more compact and lighter installation without sacrificing the performance needed to control your vessel effectively.
In short, they are quiet, efficient, lightweight and don’t need maintaining.
Downside – PMAC motors are more expensive.
In short, they are quiet, efficient, lightweight and don’t need maintaining.
Downside – PMAC motors are more expensive.