Vetus vs Mothership (electric motor test)

Getting the right Electric Motor and Prop for your narrowboat

Nowadays there are many electric motor systems on the market for narrowboats.  Back in 2016 however, the choice was limited so Mothership Marine started designing their own. On the face of it it’s not hard. You need a Motor, a motor controller, a power source, software, programming ability and a throttle. Strangely the throttle has been the most difficult to source as good quality electric marine throttles are a niche item and don’t get much interest from manufactures.

All other items are regularly used in industrial applications. The battery operated forklift truck being arguably the largest.

So it all looks easy. However, forklift trucks don’t have showers, fridges or generators or solar panels and the like.

Mothership Marine has always recognised that it is the integration of all electrical items that makes for a great boat.

However, this is a piece about electric motors and why our choice of electric motors for narrowboat is a good option.

Although DC motors are an efficient option they are mostly brushed and susceptible to burnout should the propeller be impeeded. In our opinion, the 2 options that should be considered.

  1. AC Induction Motor.
  2. PMAC Motor (Permanent Magnet AC Motor).

 

Of the 2 Mothership Marine prefer the PMAC motor. Here’s why.

Permanent Magnet AC Motors (PMACs) stand out as superior choices for marine propulsion due to their exceptional reliability and efficiency.

The motors consists of two key components: the rotor and the stator. The rotor, connected to the propeller, features permanent magnets typically made of rare-earth metals. These magnets react to the magnetic field generated by the stationary stator, which surrounds the rotor. The stator contains electromagnets powered by an AC current.

The AC current is produced by the motor controller which converts DC current (from the boat’s batteries) to 3 phase AC current and when introduced into the electromagnets which causes the rotor to rotate.

PMACs offer several advantages for marine applications:

  1. Efficiency: PMACs excel in efficiency as the rotor and stator interact solely through a magnetic field, eliminating friction and reducing wasted energy. The AC signal further enhances efficiency, ensuring smooth transitions between electromagnetic coils for a continuous, efficient rotation.
  2. Low Wear and Tear: Labeled as “zero maintenance” motors.
  3. Low Noise: PMACs operate quietly by avoiding excess friction, making them one of the quietest motor types.
  4. Power Density: PMAC produce more power compared to other motor types of a similar size.

 

In short, they are quiet, efficient, lightweight and don’t need maintaining.

Downside – PMAC motors are more expensive.

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