My first boat
I bought my first motorboat back in 2002. I was looking for a cheap 21 foot daycruiser. After checking some ads I fell in love with a Bertram 25 with a price tag three times my budget. My boss at the time told me: "Gustav, you can't by a boat with your brain. It's an emotional thing. You have to let other parts of your body decide." I followed his advice and bought this huge 1967 beauty. I had a good time with her. The best rides were with friends during the autumn in the middle of the night, in the archipelago of Stockholm. The adrenaline rush from high speed in a beautiful dark landscape is unbeatable.
The love continued for many years but two things nagged: the fuel consumption was massive and the boat slammed pretty badly in waves and wakes. With its 100-gallon fuel tank it cost me some SEK 6000 to fill her up. That is far from reasonable - it's bad for the wallet and, more importantly, every consumed fuel tank had the same impact on the environment as a round trip to Africa. And with even fairly small wakes from other boats, the ride became violent. So eventually, I decided to go for something different with less fuel consumption and a more comfortable ride.
My second boat
So I bought an Anytec - a nicely designed aluminium boat with quite a bit of V-shape which is supposedly good for the behaviour in high waves. With is narrow hull it should also be fuel efficient. The boat dealer told me 0,6 litres/NM. The reality is 1,0. So this relatively small boat needs exactly ten times more gasoline than my car. Something needed to be done. I started to look into the whole subject of efficient boat hulls.
Ten times more fuel than a car
Not very much has been done to improve the fuel consumption of recreational boats. The boats that aspire to reduce fuel consumption typically have a narrow hull and steps underneath to allow air to reduce friction. However, these measures do not come close to a reasonable solution to the problem. We still have about ten times more fuel consumption in a small boat than in a normal car.
Put wings on the boat
Soon it became clear to me that hydrofoils - wings under the boat - must be the solution. Diving into the subject I found that the technology is almost as old as the history of airplanes. It was actually an airplane inventor who came up with the idea. Thomas Moy, (1823–1910) was an English engineer who dedicated his life to airplane development. One of his key developments was a bamboo airplane with a steam engine.
In 1861, he started experiments on wing profiles under water. He did so, not to build hydrofoil, but because he found it easier to evaluate wing profiles with water instead of air. So he inadvertently invented hydrofoils. 50 years later the more well-known Alexander Graham Bell got into hydrofoils. In 1919 he was able to set the new water speed world record at a stunning 62 knots. That is fast even 100 years later. Check out his Bell-HD4 in a test run at beautiful Lago di Maggiore.
The real boom came after the second world war. Both the Russians and the Americans ran large projects to develop hydrofoil war vessels. Their main concern was not slamming boats or the cost of fuel; it was the improved range that was made possible with wings mounted on the hull.
In most applications the fuel reduction is 60-70% with hydrofoils. Having learned that, the idea to actually kick off a project to build a hydrofoil started to develop. At the same time, hydrofoils, after being asleep for 40 years, started to emerge on high speed sailing boats. Even America's Cup boats have recently started to use hydrofoil technology.
Make it electric
With a dramatic reduction in fuel consumption, maybe it would be possible to make it all electric? Since the water resistance is proportional to the weight of a hydrofoil boat, weight reduction with modern composite materials used in aviation and speed sailing may make the power requirements low enough for an electric hydrofoil to work while retaining sufficient range?
Four years ago, when I started looking at electrically driven boats, car companies started to move towards electrification. However, there was still a bit of a question whether the batteries would make it possible to build a proper electric car. Until Tesla entered the scene. The Tesla team has done a lot of smart things but to me, two stand out: First they went against the conventional wisdom that you cannot use the best batteries, Li-ion, (due to risk of explosion or fire) to reach a proper range. Secondly, they redefined the whole concept of an electric car as being something for the affluent rather the greenist. Now, they sell a lot of cars.
Based on a back of the envelope calculation I concluded that, yes, it is possible to build an all electric boat using light weight material, the best batteries, hydrofoils and highly optimised hydro- and aerodynamics.
What's in a name?
Most of the energy we use on earth comes in one way or the other from the sun. All renewable energy (wind, hydro and sun) come from the sun. With an electric boat it is possible to use only renewable energy. Therefore, it felt important to connect to the sun when choosing the name. Candela is a SI base unit for luminous intensity. It is also a beautiful name!
Now we are in the midst of working on the design, the engineering and the funding. It is fun!
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