09 Jun Inside the design of the $300,000 Arc One electric boat
Rockets and boats have more in common than you’d think, explains Ryan Cook. And while I get the feeling that he has made this point before, he’s also the guy who would know.
Cook spent nearly a decade as the lead engineer at SpaceX, developing autonomous rockets. Now, he’s the cofounder and CTO of the hyped electric boating company Arc Boats. With $35 million in funding, the 17-month-old startup will start selling its very first electric boat, the Arc One, on June 15, to be delivered this summer.
While boating is a $42 billion industry in the U.S., electric boats are a minor player. Most of the electric-boat market is for low-speed, 5 mph recreational vehicles. One exception is burgeoning performance products like the Candela C-7, which uses hydrofoils to lift the boat out of the water to reach its impressive speeds. Those foils also mean it isn’t the most flexible option for casual cruising and water sports.
Priced at $300,000, the Arc One is being built to be something like a Tesla Roadster for water. It’s a high-cost proof of concept that Arc Boats is using to show that electric boats can compete with gas boats in just about every way, and all without the maintenance or exhaust. The Arc One is 24 feet of aluminum, promising 3 to 5 hours of fun on the water per charge, with speeds of up to 40 miles per hour—largely thanks to its giant battery that’s about four times the size of what you’ll find in a base Model 3.
The stats are impressive. But in an exclusive discussion with Co.Design, Cook shared how Arc pulled them off. While Arc One’s design strategy has borrowed quite a bit from the electric car industry—so much so, that several former EV engineers are on its 45-person team—Cook says building a boat is full of design challenges that are specific to the water . . . and, yes, space.
The outer hull is more like a rocket than a car
Both a boat and a rocket start with the hull. While the paneling you see on a car is largely about decoration, crumple zones, and aerodynamics, a hull is a seamless supportive architecture. Think of a hull as both the skin and the bones of the vehicle, or the frame and the body in one.
“The surfaces you see are also structural,” explains Cook. “We’ve had challenges making sure no welds are visible, and all the aesthetic lines look crisp.”
For the Arc One, the company opted for an aluminum hull (just like SpaceX rockets), as opposed to a fiberglass hull, which is more popular in water sports. Fiberglass hulls make sense for much of the boating industry since they form in molds and can be mass produced inexpensively. But Cook lists several reasons that his company is starting with aluminum—the biggest of which is that it’s still figuring out the perfect shape for its hull.
“Gas boats have decades of refinement to their hull shapes,” says Cook. “We’re starting from scratch.”
As Cook explains, the precise shape of a hull is critical to not just the efficiency with which a boat cuts through the water, but the smoothness of its ride and the shape of its wake (and, yes, water skiers and tubers need some wake for fun). Hulls like that on the Arc One tend to be shallower for balance and maneuvering (better for lakes), while ocean-faring hulls feature a deep-V to slice into waves. And while we know a lot of best practices in hull design, optimizing every curve of a boat for a particular ride is an art and a science.
“Pretty much all the equations you use are from the ’60s and early ’70s, similar to rockets as well,” Cook says with a laugh. “But it’s all in the details.”
Aluminum hulls aren’t molded, which is a big advantage to developing a new design—a design that Arc may produce in fiberglass when it’s finalized. Instead, designers bend a metal skeleton and weld sheet metal on top of that. (It’s a similar technique to building a wooden ship or an airplane wing.) While manually laborious, this method allows the company to iterate on the slightest curves within its own hull design, and then test them on the water quickly.
Cook tells me he’s been on the water testing designs nearly every day for the past two weeks, and the L.A.-based company has been fitting the boats with GoPros to measure wake, and assessing dozens of sensors on things like the battery. “We’re trying to collect as much data as we possibly can every time we go out, so we’re armed with more information to continue to make the boats better and better,” says Cook. As such, I got the impression that the final design is being locked down in the 11th hour. But Arc is confident that the double-digit preorders it’s already received for the Arc One can be shipped within the summer.
One interesting, secondary advantage about the Arc One’s hull comes back to the aluminum. While more durable than fiberglass, aluminum is also a far better conductor of heat. Heat is the enemy of electric vehicles, which is why EVs have cooling systems simply for their battery, motors, and related electronics. But the Arc One actually uses its hull, sitting on the water, as a giant heatsink. The boat cools in the water, which enables it to charge at its fastest, highest wattage capacity. (And Cook says that Arc has developed a workaround, so fiberglass Arc boats could utilize a similar heat sink design.) For most people at launch, when high-wattage chargers aren’t available on the water anyway, they’ll be able to charge the boat more slowly overnight through existing dock plugs, or even their home EV charger on dry land.
The software customizes ride feel
If boats have a lot in common with rockets, then there’s one part of the build experience that’s completely different. “Software tends to be pretty simplistic in rockets,” says Cook. But Arc is considering how its custom software can shape the user experience and also improve the product over time.
At the moment, the company is still testing how users should be able to use the software to get more out of the Arc One. They’re experimenting with the option for speed limiters; since most people don’t need to go 40 miles per hour, a self-imposed 25 or 30mph limit would guarantee a user more range.
Arc is also looking at how user profiles could tweak the sensation of the boat’s throttle, to both optimize efficiency and experience. Boats feature a throttle control that’s basically a stick you push forward to go or back to slow. Arc One uses this throttle, too, matching conventions of typical boats. But its electric drive train has a far faster response time than a gas engine, and getting the sensation of acceleration right is key. As Arc has tested its boat more, employees have debated exactly what that throttle should feel like. Does the torque of the engine punch the moment your hand touches the stick and then taper off in a relaxed manner? Or does pushing the stick slowly crescendo the boat’s power until you reach the max? Profiles will allow both options, and possibly more.
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The boat’s (waterproof, anti-glare) touch-screen computer will allow you to swap between these different modes, much like electric cars do today. What else that touch screen will do is still up for debate. At the moment, the Arc One team promises that you’ll be able to pair a phone on Bluetooth more reliably than is possible with a lot of boats on the market today, and onboard GPS will help keep you on course while boating. The screen also will offer the driver a rear view, so they can watch a water skier in tow without taking their eyes off of what’s in front of them.
“We wanted it to be a supporting feature, not a distracting feature,” says Cook of the Arc One’s infotainment system—though, no doubt, its spartan digital design is in part driven by the company’s need to ship its product. Over time, when boats are actually in customers’ hands, Arc plans to listen for the most requested options, and offer them as simple, over-the-air updates.
And it’s that last point—ease of ownership—that ultimately may be the Arc One’s greatest advantage. Aside from its durable hull, keep in mind that the primary moving part is its single propeller (an off-the-shelf design that’s easy to replace if it breaks), and the boat ships with everything you need to operate it, ranging from a trailer to life preservers.
In other words, the only barrier standing between finishing this article and hitting the lake at 40mph is a pile of 300,000 dollar bills. Indeed, that’s yet another way the Arc One is like a rocket. Because most of us aren’t making it to the moon any time soon, either.
Source: Fast Company
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