Foiling on the Pure Pontoon

Pure Pontoon Foil-Assist, view from the leading edge
Leading edge of the Pure Pontoon Foil-Assist. Photo credit: Andy Hughes

Major Trends in Boating

In boating, two major trends are converging: electric propulsion, and hydrofoiling. In some ways, this is a coincidence, as battery-electric propulsion is coming now because of the automotive industry, and hydrofoiling has reached new prominence because of the America’s Cup. But these two technologies have the potential to address each other’s limitations.

Electric propulsion brings tremendous advantages to boating – quietness, low maintenance, instant torque, and clean operation – but it also brings a limitation: the low energy density of batteries doesn’t play well with the high drag and weight sensitivity of planing hulls.


Enter hydrofoiling. Since the 2013 America’s Cup, no team has been able to compete without hydrofoils. Not since Enrico Forlanini, Alexander Graham Bell, the Wright Brothers, and others pioneered hydrofoils more than 100 years ago have they reached the level of public consciousness they did after 2013. With its high energy efficiency (up to 80% energy savings), foiling offers the potential to address electric propulsion’s limitations, which has led to a proliferation of electric foiling craft of all kinds – boards, personal watercraft, and even a waterbike.

Foiling Boats, and Limitations

Recently, several foiling electric powerboats have joined the fray. These present a new challenge not faced by the smaller vessels: how do you deal with trailers and boat lifts, when there’s a foil below the hull? The elegant solution for most is a retractable foil – a foil when you want it, and not when you don’t. The issue is that the boat rests on the retraction mechanism. It has to be able to extend and retract, and while extended, carry the entire weight of the boat and its payload. The demands on the mechanism are so great that it becomes expensive and high-maintenance, erasing one of the big benefits of electric propulsion.

These limitations of foiling have existed since well before electric propulsion. Hydrofoils were used on ferries in Russia and elsewhere, and on military Fast Attack Craft in the US in the 1970s and 1980s. But in each of these cases, cost and maintenance were problems, and the programs were terminated. Electric propulsion solves some of hydrofoiling’s problems (like the need for short-term bursts of power to get up onto foils), but not all.

Our Dilemma

So at Pure Watercraft, we faced a dilemma: how do we realize the benefits of foiling, without consuming in maintenance more than we save? How do we deliver a better boating experience than ever before, at a reasonable cost?

The Foil-Assist

We looked to an innovation from the 1970s: the hydrofoil supported catamaran, pioneered by Dr. Gunter Hoppe of the University of Stellenbosch (South Africa). Instead of a large, retractable foil, a small fixed foil can be placed between the pontoons of a catamaran, lifting much of the boat out of the water, and lowering the energy required at planing speeds.

Here’s the foil-assist on the Pure Pontoon:

Pure Pontoon Foil-Assist, view under the hull
Photo credit: Andy Hughes

When we combine the foil assist with an efficient hull design, we can achieve high performance at a variety of speeds, across the range of sea states that a pontoon boat is likely to encounter.


What we’ve found is that on the Pure Pontoon, at a speed of 23-25 mph, the foil assist enables a 21% reduction in power. Overall, the test hull uses about 1670 Wh/mile at that speed, compared to about 1000 Wh/mile for a full foiling boat of similar size, or 3500-4250 Wh/mile for other electric planing/pontoon boats. In simple terms, a conventional pontoon boat at 23 mph uses about $1.62/mile for gas, while the Pure Pontoon at that speed uses about $0.20/mile for electricity. 


Bottom Line

But how does it feel? Anecdotally, passengers in our test hull find that it feels like a magic carpet, riding high on the water. When crossing another boat’s wake, they say they feel it, but not like in a conventional boat.

In the end, the Pure Pontoon’s foil assisted hull provides most of the efficiency and ride characteristics of a foiling boat, without the complexity, cost, and maintenance of a full retractable hydrofoil. 

Pure Pontoon Foil-Assist, view from the trailing edge
Trailing edge of the Pure Pontoon Foil-Assist. Photo credit: Andy Hughes

Top-Secret Strategy Behind the new Pontoon Boat

In November 2021, we announced a strategic relationship with General Motors to work together to make electric boats. On January 5, we unveiled a prototype of the first boat to result from that collaboration, the Pure pontoon boat. This project illustrates many of the facets of our strategy, and how it will help us in our mission to enable a new era in boating that’s more enjoyable, accessible, and environmentally friendly than ever before. 

Big Markets

Electric boats won’t solve big problems if they’re only affordable by the few. To build a really cool electric boat to serve as a small number of people’s third or fourth boat would simply be greenwashing. To really make an impact, we have to address the biggest boat markets, in a way that attracts people who would otherwise choose a conventional gas-powered boat. This pontoon boat addresses the #1 segment in the #1 recreational boating market in the world.

Performance through Efficiency

There’s no art in throwing power at the problem of how to move a boat. And it just doesn’t work with electric propulsion. Batteries are heavy, and boat drag is very dependent on speed and weight, so an electric boat that tries to solve the problem with power and achieve reasonable range uses much of the extra power just to move its battery around. If, instead, an electric boat achieves its performance by reducing hull drag, improving the propulsion efficiency of its powertrain (the proportion of power used to move the boat rather than to create heat and turbulence), and using lighter-weight components and materials, then the performance can come at relatively little cost, and the power and range can be optimized.

The Pure Outboard powering this pontoon boat has been developed over the past nine years to achieve the highest propulsion efficiency in its power range on the market. It uses a large, low-RPM propeller, a custom high-efficiency gear set, and a low-diameter motor to take advantage of passive cooling. Instead of conventional aluminum tubes, this boat emulates the functionality of the familiar pontoon boat using a new, highly-efficient lower hull design (which we’ve been developing since 2018) that uses about 20% less power to achieve the same speed.

A side effect of performance through efficiency is that the boat ends up more considerate of others and the environment. It makes less of a wake, and therefore causes less shoreline erosion, and less interference with the other people, flora, and fauna on and around the water. 

Value, and Values

Most people want more for their money. To be the choice of many, our boat must offer better value than the alternatives. The first step is to make the boating experience better than ever before, with simple controls, and quietness that enhances whatever the activity – socializing, fishing, and listening to the sounds of nature. This pontoon boat is designed for quiet and simple operation.

Next, we have to build the product in a way that’s as efficient as the product itself. By collaborating with GM in the way that we did, we get access to economies of scale in EV powertrain component production that the boat industry by itself could never achieve. GM produces about four times as many vehicles per year as the entire world recreational powerboat industry produces boats. GM has committed $35B to the development of EVs – 40% of its market cap. However the auto industry battles turn out, our bet is that GM will drive quality, cost, and performance far in excess of what can be achieved in the boat industry. We’ve also arranged with GM to provide direct assistance in supply chain management and manufacturing – taking advantage of two of GM’s most valuable capabilities. Our pontoon boat will be built with a GM automotive battery pack, using a number of other components that GM will assist us to source, in a factory that GM will assist us to stand up.

A key component of our agreement with GM is that we get access to components at advantageous prices (approximating internal transfer prices). This is how we avoid the dreaded double marginalization problem that causes prices to be inefficiently high on products built from high-margin components. That’s why every other marine powertrain powered by an automotive battery pack is so expensive, while our Pure-GM pontoon boat is priced at about the same level as similar conventional pontoon boats.

Next, we have to deliver the finished product efficiently. We achieve that by selling direct-to-consumer, enabling us to iterate our sales process regularly to reach the right people (primarily digitally) with a message that resonates, and information that helps them make well-informed decisions. It also helps us enlist customers into our army of advocates, and support them as they persuade others to boat in a better way. We build a collaborative relationship with the customer, which is much easier when you stop being adversarial. We don’t have an inflated MSRP and then wheel-and-deal. We provide one great price to every customer, which keeps us allies, and makes the purchase process faster and less stressful. 

The result of these efforts will be a better value chain than any other in electric boating, and an ability to deliver the best price/performance achievable. 

Some have asked why we chose to work with GM, given that for so long, GM was a proponent of internal combustion engine vehicles. I’d respond that by committing 40% of the value of the company to EV development, GM has shown a willingness to let go of the past and embrace a future focused on EVs. Furthermore, we at Pure Watercraft are focused on maximizing our positive impact on the world, which we can only do if we become the leaders in our field. The economics matter, a lot. By taking the leadership position in electric boats, which depends on the value chain advantage we get through GM, we can have some influence over the future direction of the industry, which can enable us to promote the kind of boating that preserves the great outdoors for future generations. 


The powertrain is about 90% of the intellectual property in a boat. Once we’ve built the powertrain, we can extend it to new boat types quickly. The pontoon boat illustrates this, as we showed a working prototype 44 days after announcing our GM deal. (Note: the prototype uses Pure Watercraft battery packs,in lieu of a GM battery pack. It informs our view of performance because it uses the production-intent outboard motors and hull shape, and can simulate performance with the GM battery pack by adding weight.) Similarly, after we complete the integration of the GM battery pack with the Pure Outboard system, we can release future boats on the same platform with an order of magnitude less work than starting from scratch. This is the power of a platform.


The relationship between people and brands is evolving. In the past, it was a one-way street. Brands designed and delivered products, and customers bought them, based on the value they saw in the product as a user. But today, people are voting with their pocketbooks, and they’re more conscious of the impact of their purchasing decisions. 

Pre-orders are another source of efficiency. By collecting pre-orders prior to production, we can develop manufacturing capacity and make supply chain decisions more rationally, so we don’t waste resources on excess capacity or fall dramatically short of demand. We can also secure financing at better terms, which gives us a better cost structure and the ability to deliver more value for a better price. This is where you come in. If you place a pre-order with us today, you enable us to produce more efficiently than we could without you.


Ready to Go

Today we announced the close of $37.5 million in financing, a follow-on to our earlier announcement from September. This isn’t the point of what we do, but it enables us to fulfill the promise we’ve made to ourselves and to the world to change boating for the better. 

This round includes some notable investors:

  • L37 Ventures, where partners include Randall Ussery, who will now join our board of directors, and Monica Lee, my first hire and director of business development at CityAuction (the internet auction site I founded in 1997) 
  • Duffy Duffield, the founder of Duffy Boats, who has sold more electric boats than anyone else in the world
  • Jeff Wilke, former CEO of Amazon’s Consumer business unit
  • Tom Alberg, angel investor and former board member at Amazon
  • Megan Smith, former CTO of the US, leader of Shift7, dedicated to increasing diversity in tech
  • Several Pure Watercraft employees

You see a pattern – investment by people who know us and what we’re doing very well. Together, we’re making boating better – better for the boater, better for the boat owner, and better for everyone else who enjoys our precious outdoors.

Thanks to those who helped us get here (including current and former employees), and those who will take us to the next level.


Powering Forward

Today, we announced funding of $23.4 million (including some conversion of convertible debt raised earlier). When completed, this funding round will enable us to build out our team and production capacity to meet the needs of our customers. 

We’ve spent the last 9 years developing the Pure Outboard – the highest performance electric marine propulsion system on the market (in terms of propulsion for its weight). While there are many different kinds of boats, the way to bring all of them into a new era that’s more enjoyable and accessible to more people than ever before is to develop groundbreaking technology from the ground up, and to find ways to power the boats people want.

To that end, we’ve recently announced complete boat packages – a pontoon boat, a bass fishing boat, and a rigid inflatable boat. These offerings make it easy for someone to choose a complete system, with the confidence of knowing that everything fits together well, and serves the purpose they intend. Pontoon boats and fishing boats are now the top categories of boat sold in the US, and rigid inflatables are the boats most often used as tenders on yachts.

To get to where we are, and where we’re going, we rely on our customers and others as part of our team. Your pre-orders, referrals, and ideas power us forward. The most powerful messages about our company, its mission, and our products come from you – at the boat ramp or dock, on Facebook or Twitter, or on Zoom calls with your friends.

Thank you for your continued support.

A Thousand Cars Off the Road

Comparison of single coaching launch and cars

What attracts most people to Pure Watercraft is the promise of a thrilling yet quiet ride in a high-performance electric boat. They want to catch more fish, have more peaceful conversations, and hear the sounds of nature. They want to tinker with boats less, and enjoy experiences more.

The environmental impact matters, too. It matters to our employees, who dedicate their professional lives to making boating more enjoyable, accessible, and environmentally friendly than ever before. And it matters to our customers, who care about taking good care of the water and the outdoors they enjoy so much.

MRA Boathouse (building and photo credit: Winder Gibson Architects)

One of those customers is Marin Rowing Association (MRA) in California. In 2014, they installed solar panels to make their boathouse carbon-neutral. They even sized their solar array to account for charging the outboard motors on their coaching launches, even though at the time, there were no electric motors capable of powering them. Enter Pure Watercraft.

MRA installing solar panels (photo credit: MRA)

MRA is purchasing 8 Pure Outboards to replace their 25 HP gas outboards, which average about 4 years old. (Normally, they’re replaced every 5 years, as they reach the end of their useful life.) Marin’s coaches understand that precise communication is key to success.  For the first time, they will be able to help the rowers improve without yelling over engine noise, and listen to rowers speaking at a normal volume. They’ll also benefit from more accurate speed control, reduced maintenance, and lower cost of ownership. (The Pure Outboards pay for themselves in 2 years, and over their lifetime, they cost less than half as much as gas outboards.)

As part of their process, Marin is applying for grants (such as the Carl Moyer Program), and quantifying the environmental impact of their conversion. The bottom line is that their 8 coaching launches, with small gas-powered outboard motors, create about the same non-CO2 pollution as 1,000 passenger cars. Think about that – each of these coaching launches that use just 2 gallons of gas per day pollutes as much as 125 cars. Imagine the more mainstream boats, like bass boats, that can use 20-30 gallons of gas in a day, polluting 10-15X as much.

MRA 50th Anniversary, with launches in background (photo credit: MRA)

Switching to the Pure Outboard, the direct pollution is eliminated. Of course, there is some pollution driven by generating the electricity to charge the batteries; however, the Pure Outboard is so efficient that on an MRA launch, it uses about 2/3 the energy per day that an electric car uses. Therefore, for MRA, switching a single gas outboard to the Pure Outboard eliminates 125X as much cancer-causing pollution as switching from a typical gas powered car to an electric car.

The beautiful thing is that the boater gets a vastly superior experience, at a lower cost, with a positive impact on the environment (including noise reduction far in excess of that required by state law) as a bonus.


The first step was to analyze the pollution from modern, four-stroke outboard motors of the type that MRA uses. 

Carbon dioxide has garnered most of the recent attention, because of global warming, but more immediate harm is caused by other pollutants: carbon monoxide (CO), oxides of nitrogen (NOx), hydrocarbons (HC), and particulates (P10 and P2.5). Catalytic converters are very good at reducing CO, NOx, and HC, but no outboard motor has a catalytic converter because they were tried (once) and failed. Therefore, non-CO2 pollution is their Achilles’ heel.

To calculate the emissions from outboards, we looked at the EPA pollution limits (which began in California with the CARB 3-Star level regulation), because the manufacturers design to just meet these limits. There was a push to eliminate two-stroke engines from outboards, but instead, CARB implemented emission standards that would apply to all engine types, and some manufacturers, like Evinrude, improved their two-stroke outboards just enough to meet the new limits. (Note: they’re much worse on particulate emissions – 30X as bad.)

Federal regulations on emissions from outboard motors depend on the power level. A 25 HP (18.64 kW) gas outboard must not emit more than 2.1 + 0.09 * (151 + 557/P0.9) g/kWh of HC + NOx, and no more than 500 – 5.0 * P g/kWh of CO, where P is the power level (in kW) of the outboard. That results in a limit of 19.29 g/kWh of HC + NOx, and 406.8 g/kWh of CO. Because there are 34 kWh of energy per gallon of gasoline, this equates to 13.831 kg/gallon of CO and 655 g/gallon of HC + NOx.

To compare outboard motors to cars, we use fuel consumption as the common metric. 

The EPA limits the emissions of cars and places each one in a “bin”, the highest level (most polluting) of which is Bin 160. Under this least-stringent set of standards, a car can emit 4.2 g/mile of CO, and 160 mg/mile of NOx + NMOG (approximately the same as “HC” as referenced in the marine emissions standards). To convert miles to gallons, we use the new vehicle average miles-per-gallon in the US of 24.9. Therefore, a new car can emit 104.6 g/gallon of CO, and 3.98 g/gallon of NOx + NMOG.

Now let’s compare these numbers. Per gallon of gasoline consumed, a car can emit 104.6 grams of CO, and an outboard motor can emit 13.831 kg (132 times as much). Again, per gallon of gasoline, a car can emit 3.98 grams of NOx + NMOG and an outboard motor can emit 655 grams of HC + NOx (165 times as much)

For MRA, that means that its weekly fuel usage of 70 gallons of gasoline drives the same amount of (CO + HC + NOx) pollution as 9240 gallons burned in cars, which is about 1000X the weekly fuel usage of a typical car. Therefore, their impact will be to reduce (CO + HC + NOx) pollution by about as much as you would if you replaced 1,000 cars with electric cars (which would cost the federal government up to $7.5 million in subsidies).

With this big an impact for one rowing club, what about the bigger picture? There are about 1,000 rowing clubs in the US, with a total of about 4,000 launches. If the average launch is used about the same amount as MRA’s, then replacing their gas outboards with the Pure Outboard would have the same impact as getting 500,000 cars switched to electric (requiring subsidies of up to $3.75 billion).

How can the impact be this significant? There are two major reasons:

  1. Gas powered cars are about 16-25% efficient, while gas outboards are only about 8%. There is much more room for improvement.
  2. Not requiring catalytic converters on outboards leaves us at the pollution mitigation stage where cars were in 1975.

We still need to take into account the compensating pollution driven by the power plant generating the electricity to charge the batteries. To do this accurately across the board would require an impractical level of complexity, involving time-of-day (to know how much power is baseline and how much is peak), the specific power plants involved, the grid efficiency, and the round-trip charge efficiency of the battery pack. The answer would vary in some cases by orders of magnitude. But we can simplify this problem by comparing to electric cars, which have the same conditions to deal with. 

By experience, we’ve found that a coaching launch with the Pure Outboard uses approximately 4.8 kWh for a hard rowing practice that would normally require a gallon of gasoline in a gas outboard. Therefore, we can translate the MRA gasoline usage in gallons by 4.8 kWh/gallon to get the electricity usage. Electric cars use between 248 and 455 Wh/mile, and the average car drives 11,500 miles/year, so an electric car uses between 2,852 and 5,233 kWh/year, with the average (weighted by sales volume) about 290 Wh/mile, or  3,335 kWh/year.

MRA uses 70 gallons of gas per week, with 8 launches, so the average launch uses 455 gallons/year of fuel. The replacement Pure Outboard will use 2,155 kWh/year, which is about 2/3 of the power used by a typical electric car. The club as a whole will use 17,472 kWh/year, equivalent to just over 5 electric cars.

Clean Slate

One of the most common questions that comes up when discussing Pure Watercraft is: why did we build so many of our components and capabilities in-house, when there are engineering consulting firms, electric motor manufacturers, and huge battery companies already serving the electric car business?

The short answer is that through the process of testing and iterating, we learned that owning the capabilities ourselves was the only way we could make something truly great – the only thing worth doing.

Product Vision
As we took a closer look, we saw that  people weren’t buying higher-powered electric outboards because they were too heavy, expensive, and unreliable. They cost so much that even when you took the much lower operating costs into account, they’d never come close to paying for themselves. Repair shops said they were even less reliable than gas outboards. Boaters said they were loud; the motor eliminated emissions but noise pollution remained. We needed to achieve simultaneous competing objectives: high performance, low cost, near silence, and rock-solid reliability. Tesla was an inspiration, having broken the previous inverse relationship between cost and performance, so we learned from them and set out to create a better way to experience the water.

In the beginning, we partnered with an outside development firm to engineer our first electric runabout.  

It emulated the fast-prototyping method used successfully to launch Internet companies, and gave us speed, which we believed was critical to validating our product idea. In the end, what we got out of it was a pricey prototype. On the positive side, through this partnership we secured a founding engineer with the insight he had gleaned from being embedded with the outside development firm. But we also realized the limitations of working with outside engineering. Much of the learning comes from the details of development and was captured externally. There also was a misalignment of incentives; because we had skin in the game, we were focused on finding paths that would lead to viable products, while engineering firms are in the business of serving the stated needs of the client, regardless of the viability of the product. After the first prototype, we concluded that we needed to build the core capabilities in-house, even if it took more time. The electric vehicle field was so new that available people with outstanding skills and experience were rare. We’d have to start with what we learned from the runabout project, and hire smart people who could learn the field. It was starting to look like a long road, but the only way to develop groundbreaking products.

The Battery Pack
We started with the battery pack because it is 50% of the weight, cost, and complexity of an electric vehicle, and a critical factor in performance.  At first, we reached out to battery companies that manufacture and sell cells, which we would use to build into battery packs – similar to the way Tesla does.

But the big manufacturers didn’t return emails from a marine propulsion start-up. We next looked at companies that built and sold battery packs made using cells from the big manufacturers, but they cost 2-4X as much as the cells themselves as a result of the battery pack IP. If we took their prices as an input cost, then our product was going to cost the customer far more than if we developed the battery pack IP ourselves. We quickly learned that we couldn’t build a competitively priced product if we outsourced the component with the most significant IP.

Besides the economics, we were concerned with performance. The Tesla battery pack was the gold standard, and none of the packs we saw held a candle to theirs in terms of energy density and capacity retention. A boat is more weight-sensitive than a car, so we had to be even more focused than Tesla on getting the most energy per pound.

But how would we build a safe pack, with high energy density, at a cost that was commercially viable, if the cell manufacturers wouldn’t return our emails? How could we build a battery pack when we had never done so? How could it outperform the packs built by big companies? We had to secure access to cells, and learning. Leading-edge battery pack technology wasn’t published. There were tear-downs of electric car battery packs and how-to’s written by hobbyists, but our goals were different than theirs. They were trying to convert an old car into an electric proof-of-concept, and we were building a commercially viable, high density battery pack that would last years.

So we found a partner to co-develop a battery pack with us. We could learn from them, and get a working battery pack quickly. Together, we chose a standard cell type, the 18650 used in power tools and Tesla cars. We thought we could outsource the battery management system (BMS), because every battery pack has similar needs. So we used the same BMS we used in the runabout. However, we later found that the BMS didn’t work on cold days – we had to use a hair dryer to warm it up before we could use it. It weighed too much, it cost too much ($1500, when the chips on it cost < $100) , and we couldn’t improve it because it was someone else’s technology.

We then took a new approach. We tried to use sub-modules from our partner, and take on a bigger share of the development ourselves, but it wasn’t enough. The result was still high cost and heavy. We had to scrap that and start over.

Finally, we got the top battery cell provider to return our emails after 5 years of pursuing them, and they agreed to supply us cells. We would be spending less than half as much on cells, for the best cells available. Our internal engineering build-up was paying off, as we now had the expertise to develop a radical new design. By developing our own BMS, we could use a far smaller set of circuit boards, built to fit our pack, instead of the mess of 97 circuit boards that the off-the-shelf BMS required. This was the fourth battery pack we developed, and finally, we had one that really excelled. It beat our gold standard “the Tesla Model 3 pack“ in energy density. The flywheel of component and team development was finally whirring, after 7 years.

The Outboard
Electric motors have been around for about 150 years: you would think there is a wide variety of motors available at reasonable prices. However most on the market are used in fixed applications, where neither weight nor size is very important, and they can use A/C power from the grid. Most of those used in mobile applications have large diameters and are heavy. Only the motors that have very high volumes of existing products using them are produced at low cost – for example, motors for quadcopter drones. If it’s more powerful than a drone, but less powerful than an electric car, then there are only low-volume, high-cost motors out there.

We looked into building our own motor, as Tesla had done. But where to look? We reached out to one of the gurus of motor design to point us in the right direction. When we explained our objective, he knew what we needed to do, and shockingly, he said he’d do it himself.  We could now build a motor that, compared to those we had found, weighed about half as much, had about 1/3 smaller diameter, and cost 2/3 less per unit. We did it. Our process was unconventional but we created a motor with weight and performance only found in scientific motors, for a fraction of the cost.

In our effort to build the other components, we were often met with similar issues that we faced with the motor. The propeller became a component of surprising importance. Most electric outboards used generic off-the-shelf propellers, but we worked with a skilled propeller designer who ran computer simulations of the performance of design and materials choices. The electric motor’s ability to deliver full torque across a wide range of RPMs enabled a propeller with 30% more efficiency than the off-the-shelf ones.

In the end, our product achieved 3X the propulsion per pound of best electric outboards, and more than 2X the propulsion per dollar.

This could not have been achieved by buying our components off the shelf, as most others did. In designing our own components, we integrated components that we had previously imagined as separate, thus reducing the number we needed. Our relationships with manufacturing partners grew stronger as we sourced more and more components from them.

It would be neat to say that that’s why we built our own components, but we really stumbled into it, through the fog of uncertainty, feeling our way, learning at every stage.

A scene from the road trip with the prototype outboard

Why an Outboard?

After my early experiences in boats led us to launch Pure Watercraft, we had to decide what to build first. Why an outboard motor? Why this power level?

The answer begins with my move to Seattle. I came here for the first time in 1984, to row in the Opening Day regatta, so I got to know the city from the water first. Seattle lies between Lake Washington and Puget Sound, and is bisected by the ship canal, through which every year pass thousands of boats, and hundreds of thousands of salmon.

Olympic rowers (like those depicted in Boys in the Boat) are public figures, and the biggest annual event is Seafair, a hydroplane race and associated revelry on the lake.

The Boys in the Boat, 1936 Olympic Gold Medalists
Seafair Revelry

Of course, I wanted to live on the water, and you can’t live on the water without a boat. A Sea-Ray was a popular boat on Lake Washington, and when a deal came up on a 21-footer that a friend of a friend was selling, I snapped it up. It was just the right size for entertaining, but a real pain to use and maintain (as other owners will attest). While I had experience in a few different boats, this was the one that drove me to look for a better way.

So when I started Pure Watercraft in 2011, I set dreams of a quiet fishing or coaching boat aside, and set about to make a better runabout, starting with a used 21-foot Cobalt I bought on Craigslist. A Cobalt is a high-end, well-built boat that dominates lakes like Lake Washington and Lake Tahoe, and our job was to make it an even better experience – quiet, easier to use, and with a more powerful hole shot. The first step was to pull out the monstrous, 800 lb V8 engine, and then figure out how to make the boat electric. Coming from the software/internet industry, I was focused primarily on speed, so we worked with some outside contractors to get something prototyped as fast as possible. To make a long story short, we ended up with a boat that performed like a champ (48 MPH top speed), but had some downsides. Along the way, we learned a ton about batteries, motors, motor controllers, and all the other tech that has to go into an electric boat.

The Converted Cobalt, above and below the water

At that point, we weighed our options. On one hand we could try to make a commercial version of the boat we prototyped. To delight customers with its carrying capacity and range, it would have required about 50% more battery, and 1,000 lbs less weight. The cooling system pumps and gear sets would have to be made quieter (because they were now the loudest things on the boat), and the whole system would have to be re-engineered to make it simpler and more reliable. The cost of the components would have driven us to a price point of at least $200,000, and hitting our performance targets would have required innovating on the hull as well as the powertrain. You could get a 21-foot Cobalt for $85,000 that would go all day, or a $200,000+ electric boat that provided a much quieter ride, with serious range limitations (full throttle for maybe 40 minutes). On top of that, the runabout market was smaller than we had originally thought (there just aren’t that many waterfront homeowners with $85,000+ to spend on a nice boat), and getting even smaller after the 2008 Great Recession.

On the other hand, we could consider the product I was always hoping to build eventually – an outboard to power smaller boats. While it was the kind of boating that meant the most to me, it always seemed that such a low-priced product might not be the best market. But as it turns out, what this market lacks in price, it makes up for in volume. The childhood experiences that led me to boating in the first place were ones I shared with millions of others. 20 million people fish for bass in the US every year, and there are 2.5 million boats in the US alone powered by 10-50 HP outboards, and more than 5X as many worldwide. While the outboards themselves are well-engineered (given their constraints), the rest of the systems are a mess. I’m sure the engineers work hard to get every ounce of weight out, but then the customer adds a lead-acid starter battery. The gas tanks are often red cans that you have to pick up to tell if they’re empty.

It’s just impossible to engineer an elegant, long-life, small gas outboard system. While I have vivid memories of our struggles with small outboards, we never owned one, so I didn’t know that they were so short-lived. Boaters who use them a few times a week told us they had to replace them every 5 years, even in freshwater. The warranties are short – typically 3 years for recreational use, or 1 year for commercial.

The other factor for us to consider is that we’re starting from zero. How do you ship and support a big runabout that weighs thousands of pounds? At least with a small outboard you have the possibility of shipping the customer a replacement and getting the original back. And it allows us to concentrate our efforts on the narrow task of propulsion.

So it was decided; we would build an outboard in the 10 to 50 HP range.

Why We Do It

“What possessed you?” asked University of Virginia rowing coach Kevin Sauer in 2016, toward the end of a long conversation about the details of the outboard motor we were developing.

There are reasons we built the outboard motor we did, but the more important question is why we’re on this mission in the first place. What drives us is the opportunity to change boating for the better, to get more people out on the water, appreciating it like never before.

I grew up fishing for bass and bluegill at Lower Otay Lake, in San Diego County, California, about four miles from the Mexican border. In the hot, dry climate, the lake was an oasis, where my dad and I would sometimes fish from shore, and sometimes take a rented rowboat or outboard boat and catch bluegill to take home. Later, a friend and I would catch crawdads at the local farm pond and take them with us, to sell as bait. The San Diego lakes had recently become renowned for record bass, but we never caught much. My most vivid memories of that time are of walking around the lake, looking into the water for fish, seeing dragonflies on cattails, and struggling with a rented outboard that wouldn’t start.

Fast forward to high school, where I discovered the sport of rowing. In a quaint New England town, the river was a window onto the changing colors of the leaves, the snow falling, rising and falling tides, and ice breaking on the first row of the spring. We felt the river through all our senses, escaping the classroom to strive for perfect harmony and rhythm, sometimes distracted by the rumble of the outboard on the coach’s launch.

My love of the water and boats is far from unique. Boating has been part of human history for at least 800,000 years, since before homo sapiens. About half the US population goes out in a boat every year. It’s part of our heritage, but it has been suffering in recent years. While participation is rising, boat ownership has been declining, and the age of the average boat buyer keeps going up. People want to go out on the water, but they don’t want to own today’s boats.

This is the problem we’re trying to solve. We want to connect more people to the water they love, by making it a better experience for those who own and operate boats, and for those who share the water with them. None of today’s technologies, even electric propulsion, makes boats quiet, powerful, environmentally friendly, and affordable; therefore, new technologies must be developed.

So this is our mission: to build the technology that enables a new era in boating that is more enjoyable, accessible, and environmentally friendly than ever before.

Pure Watercraft’s New Battery Pack Dramatically Increases Range For a Powerful & Clean Boating Experience

Seattle, WA  December 13, 2018  Located on the shore of Lake Union, Pure Watercraft set out to redefine boating with their Pure Outboard electric motor. In the process, they developed a battery pack with the highest energy density in marine, matching that of the best electric cars.

The 118 lb battery pack uses industry-leading Panasonic lithium-ion cells and has a capacity of 8.85 kWh. More energy per pound means a boat can get up on plane more easily and stay on plane for longer. Active thermal management leads to longer battery life and the ability to travel greater distances at high speed.

It’s also clean. The Pure Outboard emits no exhaust or noxious fumes, spills no oil or gas into the water, and is whisper quiet. It starts at the touch of a button, is immediately ready to drive, and charges easily via a standard 120V or 240V outlet available in most garages and marinas. Between the savings in fuel costs and the elimination of maintenance costs, a typical outing will cost about one or two dollars in electricity.

“Our team built the outboard motor and battery pack system from the ground up”, says Andy Rebele, founder and CEO of Pure Watercraft. “Throughout the process, each component has been designed to maximize efficiency.” 

The current system is set to replace traditional combustion outboards up to 40 horsepower. Range depends on use: a typical  aluminum fishing boat equipped with two battery packs could go at a trolling speed of 3 MPH for about 50 hours, or 25 MPH for about an hour. Charge time is as fast as 90 minutes from half to full charge using a 240V outlet.

The quiet speed of the outboard has already caught the attention of anglers seeking a competitive edge. Likewise, elite rowing teams such as Harvard, Yale, Stanford and the University of Washington have pre-ordered the Pure Outboard for their coaches. “We’re eagerly awaiting the Pure Watercraft system because it will transform how we coach our team,” says Michael Callahan, Head Coach of men’s rowing at University of Washington.

Pure Watercraft is starting customer deliveries in January 2019 and is currently accepting $500 pre-order deposits. A system starts at $14,500 for a Pure Outboard motor and one battery pack.

Product Features:

Pure Outboard Battery Pack

  • Voltage (nominal): 350V
  • Capacity: 8.85 kWh (multiple packs can be combined for larger capacity)
  • Cells: 18650 form factor
  • Weight: 118 lbs
  • Water Resistance: IP67
  • Thermal management: Active

Pure Outboard Motor

  • HP: 40 HP equivalent
  • Weight: 110 lbs
  • Water Resistance: IP67
  • Voltage (nominal): 350V
  • Prop RPM at peak power: 1500 RPM
  • Propeller: 16″ diameter 3-blade propeller
  • Motor: 20 kW continuous power PMAC motor, passively cooled underwater in line with propeller
  • Motor controller: closed loop liquid cooled
  • Gear set: two-stage, 7.67:1 reduction

Wye Island Challenge – an Epic Marathon

Wye Island Challenge Pure Watercraft

The Wye Island Challenge is an electric boat race that has run annually since 2001, which makes it a pretty unique venue to test electric boats. We took the Pure Outboard there to see how it stacked up in real-world conditions.

Entries this year included a wide variety of hulls and power trains. There was a hydrofoiling boat built from a canoe hull, with two pedal-controlled rear foils and a front foil with automatic leveling. Last year’s winner and record holder John Todd came with the boat that won last year, a very efficient single hull that planes easily. Other entries included a rare Boston Whaler catamaran, a converted rowing shell, the ‘Erged On II’ which had won years ago (now with a 14 year old pilot), and a bright yellow single hull boat. In all, there were more than a dozen entries. The most common power train was a Torqeedo that had won on various hulls from 2013-2015, and some competitors had ‘overvolted’ it by adding more batteries in series to get a little more power. John Todd’s record holding boat used a custom built system with a larger motor, with air cooling.

We mounted the Pure Outboard on a new Still Water Design  hull, and its first outing was the test run on the Wye the day before the race. It’s a tri-hull craft with a center pontoon slightly higher than the two side pontoons. Instead of the normal bench seat, we had a simple chair set up for a single driver.

Off we went at the starting horn, with a turn around the first day marker, and the Pure Watercraft entry got ahead of the pack, setting the pace at 21 MPH. John Todd caught up, though, and held steady as the course crossed the channel, with the occasional huge wake, which John’s boat traversed without hesitation. Approaching the lighthouse that marks the entry to the Wye River and the beginning of Wye Island, the other boat fell back, and we discovered later that it was because the motor had overheated and failed (blew up might be a more apt description). The race got lonely, as the Pure system kept ahead and reached the required rest stop at the halfway point, and spent the 10 minute stop alone. After starting the second half, approaching Wye Island again, a couple of other competitors were spotted approaching their rest stop.

The return trip was more ‘adventurous’. The Pure boat ran aground on mud on the side of Wye Island, and worked itself free after a minute or two, and some serious doubts about whether a rock or oyster bed might have done some damage, but the motor had emerged in fine shape. Entering the channel for the final crossing back to the starting line, the most treacherous section of the race, there was a clear shot home, but the gargantuan yachts that ply those waters are not accustomed to slowing down for small boats. When the Pure boat was less than ¼ mile from the finish line, three yachts silently conspired to send wakes from all directions at once, and the boat got inundated, salt water over everything. After blowing water out of the prototype connectors (the permanent ones are waterproof to an IP67 rating), the system started back up again and finished at the same speed at which it started: 21 MPH.

Unfortunately, no one was there when the boat finished. The ‘officials’ didn’t anticipate anyone finishing that early, so they were nowhere to be seen. We took our own finish time, which was 1 hour 10 minutes to the original start line. The previous record was 1 hour 35 minutes, and the previous multi-hull record was 2 hours 13 minutes. The margin over the old record was about 1 minute per mile, so instead of 4 minute miles in the previous fastest boat, the Pure boat did sub 3 minute miles.

See our course and a video of the adventure:

Wye Island Electric Boat Marathon 2017

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