Range

People always want to know what the range of an electric boat is. It’s a reasonable question: batteries are much, much less energy-dense than diesel or gasoline, and we’ve seen from the transition to electric cars that “range anxiety” can both slow down adoption and be a real source of stress for adopters.

Unfortunately, it’s a much harder question to answer for this boat than it is for a car. For one thing, a boat’s power use is extremely sensitive to how fast it’s going. It is completely meaningless to ask how far you can go without specifying how quickly you want to get there. You can see this in the chart below: look at the middle dashed line, which shows the estimated range on a fully charged battery. That’s 250nm going a leisurely 5kts down to only 33nm when going 10kts.

Complicating things further, though, are the solar panels that recharge the battery as you go. You could say that the range was “infinite” since, given enough time, you can go as far as you want without ever plugging in, but that’s also pretty meaningless. The only metric that seems to make sense is how far you can go during some fixed period of time. Looking at a single day didn’t make sense because cruising trips are often sporadic: you spend a couple of days here, quick hop over to the next island, spend a few days there waiting for a weather window, then a long passage across the strait, and so on. So I thought it was better to look at the range for a week. That’s where you see that in the summer months, you should get almost 600nm per week going 5kts, or 200nm at my preferred cruising speed of 7kts. Mind you, if you start with a full battery, you can add on the battery amounts. So in theory, at 5kts you have 850nm in your first week; you could run 24/7 from Seattle or Vancouver down to San Francisco at a respectable 120nm per day, though that’s assuming absolutely perfect weather.

As a final complication, solar is, of course, very dependent on both season and location. The numbers you see here are for the Pacific Northwest; a similar boat in the tropics would do much better! But in our winters, the solar-powered weekly range goes down dramatically, and in practice, you’re either only taking it out for a weekend daytrip, or you’re plugging it in. (Luckily, at least where I live, it’s a lot easier to get dock space and shore power in the winter months).