1.3 loud vs. quiet (gearbox vs. direct drive)

Boat motors are available with direct drive and with a gearbox. A direct drive is usually much quieter. In exceptional cases, some noise is also generated by motors without a gearbox. Depending on your application, both variants can be advantageous. You will learn the advantages of each type and receive suggestions on different performance classes.

Electromobility from our point of view means above all peace and quiet on the water. The biggest advantage is not to have annoying noises while driving and to be able to talk relaxed.

There are different techniques with electric boat motors. On the one hand noiseless motors without gearbox and on the other hand E-motors with gearbox. These cause an audible mechanical noise, depending on the manufacturer even a relatively unpleasant whistling sound.

Basically, the volume is especially relevant for outboard engines that are operated by tiller. The same applies to smaller boats, where the engine is very close to the driver and is therefore easily audible. Therefore, the differences appear mainly in the engines with power between 1 to 11 kW. Above 11 kW, many boat engines have a gearbox integrated to convert the power of the engine into speed accordingly.

The further away the engine is from the driver, the less relevant the noise level of the engine itself. The same also applies to inboards, saildrives or pod motors. Since the noise is almost always negligible due to the location in the boat.

Here we show you our selection of the best electric boat motors in the range of up to 6 kW. The ePropulsion drives were available up to 6 kW first without a gearbox. In addition, the price-performance ratio is somewhat better than other manufacturers. Also recommended are the Torqeedo Travel models and the Trend motors from Aquamot.

Here you will find the most popular drives from 8 kW. The 10 kW Propel is a very efficient direct drive with an excellent price-performance ratio. Other e-motors in the 8 kW range are available from Aquamot and E-Tech.

Gear-driven motors usually have a decisive advantage: the resistance under water is significantly lower. In a motor with direct drive, the motor is in the housing under water. However, the design provides a significantly greater water resistance.

Due to the increased water resistance, more power is required for the same speed or the final speed of the boat decreases slightly. For planing boats, motors with gearboxes are therefore partly better suited. 

It really depends on the manufacturer and the technology of the engines. We can give a good general estimate, but we often recommend a test of the engines or at least watch a video with the engine in action.

There are also exceptions where the motor with gearbox from experience is hardly louder than a motor without gearbox. An example of this are the drives from RiPower. The engines are quiet thanks to the good workmanship and at the same time especially suitable for a sporty driving style.

From a technical point of view, the direct-drive motors are somewhat more efficient. Thermal energy is generated by the mechanical transmission of power in the gearbox. Through the movement, there are therefore losses in efficiency. So for the same performance, more energy is needed.

However, it is questionable how the lower efficiency compares to the increased water resistance. The bottom line is that the result in terms is probably very comparable.

In addition to the factors mentioned above, other aspects also play a role in the selection. These are mainly advantages for the direct drives: motors with direct drives are usually lighter, simply because there are fewer parts in the housing. Whereby there can be significant differences between the individual manufacturers. Thus, the models of Torqeedo are usually lighter than those of the market companions.

Due to the direct drive, separate cooling is also not necessary and the motors are all in all usually cheaper. So, all in all, the motors with gearboxes are much more complex. Especially for displacement boats, a direct drive is almost always the best choice. For sport boats, a gearbox is often more suitable to better influence the speed of the propeller.

It is not only the gearbox that offers some distinguishing features in the e-motors. In the rear motors there are brushless motors and motors with carbon brushes. Experience has shown that the brush motors from Minn Kota are particularly quiet. In particular, anglers should rather reach for a Minn Kota. In theory, this is a wearing part, but in practice it hardly needs to be changed.

Brushless motors also fulfill your purpose, of course, and do without wearing parts, but also generate some background noise. For this, these are often somewhat cheaper.