Product26 January 2026

How Far Can an Electric Boat Go? Range and Speed Explained

By Jason Rieck
Co-Founder & Lead Designer, Cat Cruisers

How far can an electric boat go on one charge? It's the first thing almost everyone asks us. The honest answer: it depends on hull shape, battery size, motor efficiency, speed, wind, current and how much you've loaded on board. Here's how it works, in plain English.

If you've towed a caravan, you already understand it. Your car's fuel use jumps when the van's on the back and you're driving into a headwind. Boats work the same way, only more so.

Cartoon of Jason driving a ute towing a caravan into a howling headwind on a Queensland coastal highway, grimacing, while his co-host DJ holds her hair and points at a thought bubble of a gauge dipping into the red — Headwind plus a van on the back: the fuel gauge knows before you do.

Knots and nautical miles, quickly

Boats measure distance in nautical miles. One nautical mile is about 1.85 km. Speed is measured in knots, which means nautical miles per hour, so 5 knots is a bit over 9 km/h.

What real electric boats are doing

Range varies a lot from boat to boat, and it drops quickly as speed goes up. One of the best-known long-range examples is a Swedish boat, the Candela C-8. It uses computer-controlled underwater wings called hydrofoils to lift the hull out of the water, a bit like a water-skier rising up as the boat pulls them along. Less boat in the water means far less drag. Its maker quotes a range of up to 57 nautical miles (about 105 km) at 22 knots. Boats without foils usually get much less range at that kind of speed, and the reason is the big one below.

Cartoon of the Cat Cruiser catamaran towing Jason on two water skis across a calm Gold Coast bay, grinning, while his co-host DJ cheers from a timber jetty and a dolphin pops up to watch — Hydrofoils lift the hull like a water-skier: less in the water, less drag.

The big one: going faster drains far more than you think

Here's the bit that surprises people. As a rough rule of thumb, the power a boat needs climbs with the cube of its speed. In plain terms, double your speed and you need roughly eight times the power. For example, if a boat needs 2 kW to cruise at 5 knots, it needs roughly 16 kW at 10 knots. Real hulls don't follow the rule exactly, but the pattern holds: a bit more speed takes a lot more power.

Think of riding a bike. Cruising along is easy. Try to go twice as fast and you're not working twice as hard, you're gasping.

Cartoon of Jason pedalling flat out along a marina path, red-faced, with a row of eight buckets of sweat behind him, while his co-host DJ cruises beside him sipping an iced coffee with just one small bucket, the Cat Cruiser catamaran moored behind — 2x speed = roughly 8x the effort. Eight buckets, one very sweaty rider.

This applies to every boat, not just electric ones. Petrol hides it because a fuel tank holds so much energy. With batteries (measured in kilowatt-hours, or kWh, the same unit as on your power bill), every kilowatt-hour counts, so taking it easy is the secret to range.

There's also a sweet spot. Most electric boats push through the water rather than skimming over it, and they're most efficient well below the hull's natural top speed. Push harder and the boat starts trying to climb over its own bow wave, like running up a sand dune that keeps piling up in front of you.

Cartoon of Jason sweating as he pushes a wheelbarrow up a beach dune while a wave of sand piles up in front of the wheel, as his co-host DJ laughs under a beach umbrella and a seagull watches — Push too hard and you end up shoving your own sand dune.

Why the boat's shape matters more than the battery

It's tempting to think range is all about battery size. But hull design matters just as much. Slim hulls make smaller waves as they move, and for many boats that means less drag than one wide hull, though it depends on the design. Two slim hulls slice through the water like a pair of knives. A single wide hull shoves more water out of the way, more like dragging a spoon through custard.

Cartoon of Jason's co-host DJ winking as two slim, smiling butter knives glide through a giant bowl of custard, while Jason pushes a strained spoon that bulldozes a big custard wave and splatters him — Slim hulls slice like knives. Wide hulls shove custard.

Weight is the other big factor. Every extra kilo takes energy to push along, and batteries are heavy. Add more battery and you add more weight, so past a certain point, extra battery actually hurts range. It's like packing a bigger esky for a long day out: more drinks, but a heavier load to lug. Good design finds the balance.

Cartoon of Jason sweating as he drags a big esky along a jetty toward the moored Cat Cruiser catamaran while his co-host DJ laughs and keeps tossing in more cans, watched by a pelican — Bigger esky, more drinks, slower bloke. Batteries work the same way.

Topping up along the way

Solar can help, especially in Australia. Coastal north Queensland averages around 5.5 kWh of sunshine per square metre per day across the year, so panels on a catamaran roof can put energy back into the battery at anchor or under way. Solar stretches a sunny day. It doesn't replace charging.

Fast charging for boats is starting to appear too. Australia's first electric-boat fast charger was installed at The Quays Marina in Church Point, Sydney, in 2023. It's early days, so for now many electric boaters charge overnight from a standard 15-amp outlet (the caravan-style plug) or marina shore power.

What that means for a Cat Cruiser

Cat Cruisers are designed around the way Australians actually use boats. Twin electric motors (5 kW each on the 650, 10 kW each on the 870) draw from a 60 kWh drive battery. The 5,000 W of roof solar helps stretch a sunny day, a fast charge takes about an hour, and a separate house battery looks after life on board. The twin hulls are designed to make the most of every kilowatt-hour.

And because every Cat Cruiser is trailerable, range means something different. You're not stuck on one waterway. Tow to a new spot, charge up, and explore a different stretch of water the next day. The range isn't just what the battery holds. It's everywhere you can tow the boat and plug it in.

Cartoon of Jason's co-host DJ pushing one more pin into a map of Australia on a caravan-park noticeboard while Jason leans on a ute towing the Cat Cruiser catamaran on its trailer, and a kookaburra sits on top — Range = the map, not the tank.

Curious how range works in real life? Have a chat with the team at catcruisers.com.au/contact.

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