pmr sailing: Electric Powerboating – How Long Does a Battery Last?

Electric Powerboating – How Long Does a Battery Last?

One of the most common questions we get asked about our electric Whaly safety boat is:
“How far can it go on one charge?”

So we decided to find out. With an 85km estimated range and a 3kW electric outboard powered by a 30kg lithium battery, it was time to see what it could really do on the River Thames.

Our boat:

The goal: real-world use over several weeks — safety boat duties, filming, setting marks, light ferrying.

We didn’t just do a lab test. We did real powerboat jobs on real days with real wind, current, and unpredictability. Here’s what we found:

Typical safety boat usage (start/stop, 60% throttle):
~20 hours of operation before dropping to 20% battery.
The advantage of the Electric Boat is that when we are not moving, we use no power.
Light cruising (50% throttle):
Around 85km range as advertised — especially in calm conditions.
Full throttle (getting to a capsize quickly):
Power consumption jumps — range more like 40–50km.
Cold weather performance:
Slightly less range (about 10% drop on colder mornings).

Slow and steady wins the battery race.
The moment you crank the throttle, your range falls fast.
Regenerative braking? Not a thing on boats.
Wind and stream matter. Fighting the current costs power.

But best of all, it’s silent. No petrol smell, no ear-rattling outboard noise. Just the quiet hum of the water and a low electric whirr.

For our kind of use — club safety boat, filming, and general duty — we easily get through a full day (usually two or more) before recharging.

And with solar charging at home, we haven’t plugged into the mains once this season.

Electric boating? It works. And for the Thames, it’s ideal.

📖 Read more about our electric setup at:
https://pmrsailing.uk/The-Camera-Boat/Drop-Front-Wonder.html