Installation of an electric pod motor in a sailboat 🛠️

Our customer's boat is a Hallberg Rassy 26. The boat is from the year 1979.

The boat has a weight of 2,500 kg, an overall length of 7.95 m, and a waterline length of 6.7 m. Calculations result in a hull speed of approximately 6 knots, or 11 km/h.

The owner wanted to get as close as possible to the hull speed during the consultation, with a travel time of 5-6 hours at 4 knots, meaning a range of at least 20 nautical miles. The installation of the electric pod motor in the boat was successful.

According to the calculated theoretical travel curve, a continuous power of around 1.3 kW per hour is required for a speed of 4 knots. For a speed of 5 knots, it is already around 3.5 kW per hour. Here you can clearly see the exponential relationship between consumption and speed.

In summary, for the customer's requirements of 4-5 knots, a motor with 4 kW power should actually be sufficient. However, to keep the boat maneuverable in wind and weather, we recommended installing a 6 kW motor – also because there are not many options on the market between 3 and 6 kW. For the desired travel time, 2 batteries with 5 kWh each are needed.

For the past 3 years, a Volvo Penta MD2020 with 19 HP has been installed. This served as a replacement engine for the original Volvo Penta MD2010, which had suffered damage to the exhaust manifold.

The MD2010 had an output of 10 HP. Before that, in the 1990s, there was even only an MD5 replacement engine installed with 8 HP.

The 6 kW ePropulsion can easily replace the 8 or 10 HP.

Removal of the old diesel engine
The removal of the old saildrive had already been carried out by the owner, saving us a lot of time during installation. The tank, hoses, and throttle lever had also been removed.

Installation of the pod motor
The existing saildrive foundation could be reused. Due to the already existing hull opening, the installation was completed a bit faster. It is important to seal the drill holes and the foundation at all points – that is, at the motor bolts and also at the cable duct.

ePropulsion has a special adapter plate for installation on saildrive foundations. The adapter plate also makes it easier to install the motor. The controller is located directly in front of the pod motor. Cables run from the controller to the battery and to the throttle/display.

Installing and wiring the batteries
Adequate space plays a major role when choosing the batteries and their location in the boat. Ideally, you should have good access to the battery terminals and there should be enough space for the wiring.

When connecting two or more batteries in parallel, it is important to ensure equal resistance in the positive and negative cables and to charge both exactly the same.

The correct balance guarantees equal charging and discharging currents, which extends the lifespan of the batteries and minimizes operational errors.

Even though the ePropulsion manual does not mention extra fuses, we usually install fuse holders, fuses, a shunt for additional monitoring, and an extra main switch in the system.

Third-party batteries cannot be integrated into the ePropulsion display, so separate monitoring of the remaining capacity is very important to us. Some systems, such as the Victron BMV, can also calculate the remaining driving time.

Additionally, the batteries already came with small displays for evaluation, so we installed both screens as well. In this case, a DC-DC converter is also installed, which supplies the 12V battery with power from the drive battery.

After the installation of the motor, the controller, and the wiring of the batteries, the throttle lever and the display were mounted. In addition, the propeller had to be mounted on the motor.

The ePropulsion Pod 6.0 EVO has a 3-blade aluminum propeller. Under sail, the pod motor slows the boat by about 1-2 km/h (0.5 - 1 kn). Optionally, a folding propeller can also be used, which folds in under sail and has less water resistance. Without a folding propeller, the pod motor can regenerate power while underway (but only in combination with ePropulsion batteries).