How far can we go? Electrically…

With cars, everyone started talking about range anxiety. Which proved out to less of an issue, especially here in the Netherlands, then we thought it would be. For boats, it seems everyone needs to take care of charging themselves. So if you harbour supports (fast) charging, you are in luck. Otherwise, well, don't go too far.

So, How far?

But how far can you go with an electrical boat? There are many factors to take into account. We use these ourselves too, to figure how much power and battery we will we need. We'll discuss these here.

Power

To determine the power, first some basic information regarding electric sailing. These are some basic numbers to follow for the required electrical power for full displacement boats.

• 2 – 4 kW (5 – 8hp) Up to 6m length or 2 tons of water displacement
• 4 – 7.5 kW (10 – 15hp) Up to 8m length or 3 tons water displacement
• 10 kW (20hp) Up to 10m length or 7.5 tons water displacement
• 15 kW (30hp) Up to 12m length or 10 tons water displacement

Speed

The same speed as a boat with a diesel or petrol engine is of course possible. It must be taken into account that non-planing boats have a maximum speed equal to the hull speed. The closer to that hull speed, the more energy is consumed or wasted. Sailing above hull speed requires much more power, and therefore consumption. A more economical cruising speed is slightly lower.

Range

The range depends on the battery capacity, speed and weather conditions. As a rule of thumb:

• At economical speed: roughly 1 hour per 10 kWh of battery capacity per kW of motor power
• At full speed: roughly 0.5 hours per 10 kWh

So with a 4 kW motor and 40 kWh batteries, you could cruise for about 10 hours at economical speed. That's plenty for most day trips!

Charging

Charging infrastructure for boats is growing rapidly, especially in the Netherlands. Many marinas now offer charging points. Fast charging (50 kW and above) can charge most boat batteries in a few hours.

The future is electric, and the range anxiety that people feared is proving to be much less of an issue than expected – just as with electric cars.