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The Quadrofoil: Ecologically-sound electric hydrofoil sportscar for the water


May 17, 2012

The Quadrofoil

The Quadrofoil

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The field of motorized recreational toys is currently undergoing a renaissance due to the availability of high performance electric motors, new materials, computer aided design, new manufacturing techniques and a new wave of educated designers with no understanding of the word "cannot."

The Quadrofoil is a prime example of this phenomenon, having been created by three young Slovenian designers inside six months, and launched at Slovenia's Internautica exhibition last week.

So successful has been the response from the public that a short production run of 100 units will be completed before the year is out, giving the Quadrofoil a concept to market time of less than 12 months, and with some ambitious plans for faster future models and perhaps even a race version. The company is now in capital raising mode to fund production plans for more than 10,000 units a year from 2013 onwards.

The retail price of the Quadrofoil will be EUR15,000 (US$19,100) and a spot on the waiting list can be secured with a EUR5000 (US$6,370) deposit.

What you get is a two-person electric hydrofoil which offers completely silent running and a 40 km/h (25 mph/22 knot) top speed, along with the fast-turning the dynamics of a "sports car for the water."

One of the greatest advantages of the Quadrofoil is its lack of emissions and hence impact on delicate marine ecosystems. By comparison, most Personal Watercraft with the throttle wide open will burn a liter of gasoline per minute and dumping that quantity of burned hydrocarbons into a river or lake is unsustainable and unjustifiable in the long term.

Another advantage of the Quadrfoil over PWCs (and plus for the marine environment) is that in addition to being silent, it does not create a wake at speed, as it does not displace a significant amount of water.

Due to the remarkable efficiency of hydrofoils, it achieves its 25 mph top speed with just one 3.7 kW electric motor, and thanks to its lightweight (150 kg - 330 lb) carbon fiber and Kevlar body and in-built 4.5 kWh lithium batteries, it has a range of 100km (62 miles). It can also be recharged from a domestic powerpoint in an hour, or via the flexible solar panels which come with each Quadrofoil and are designed to be folded inside the watercraft as an emergency power source, or to top up the battery when "off the grid."

Though the term hydrofoil refers to any fin, keel, rudder, flipper, wing or foil which operates in water, man-made or otherwise, it is commonly used for the wing-like structure mounted on struts below the hull of a variety of boats. It is also used to refer to the boat to which hydrofoils are attached.

The hydrofoil's efficiency comes from its ability to lift a boat out of the water during forward motion, reducing hull drag to near zero into the bargain. Without all that surface area upon which turbulence and drag can act, there's only the much smaller surface area of the hydrofoils and aerodynamic drag to limit top speed.

This means the speed of a boat equipped with hydrofoils is either greatly increased, or the amount of power required to propel it is greatly reduced, in comparison to a boat that does not have hydrofoils.

It is hence not surprising that the world sailing speed record, and the human-powered water speed record both belong to watercraft with hydrofoils.

Going one step further, the Slovenian team used biomimicry to develop the shape of the hydrofoils and claim to have been so successful that the foils create less drag at speed than the air resistance of the hull above the water surface!

Another benefit of a hydrofoil is the comfort factor for passengers - as once the hull has been lifted above the waves, the incessant pounding disappears and the boat feels like it is flying. Indeed, a hydrofoil is a wing that "flies" in water, and the flight of the Quadrofoil is only disturbed by waves greater than 20 inches (50 cm).

The designers claim the Quadrofoil is unsinkable, and it is designed to always return to upright should you manage to overcook it in a tight turn.

One of the key enablers of the machine was the development of a hydrofoil-folding mechanism, which enables the six kilogram hydrofoil legs to be adjusted during use, and to be folded upwards by means of a manual or electric winch before entering a swimming area or approaching shore. Once the hydrofoil legs have been turned upwards, the Quadrofoil has a draft of just 6 inches (15cm).

The folding legs can also be removed, making for an easily transportable machine at 150 kg and 10 feet (3 m) in length.

Due to the low power of the 3.7 kW motor, the Quadrofoil belongs to a category of watercraft that does not require registration, a PWC license, insurance or navigation permit in the EU.

The future looks bright for the Quadrofoil and already development of a much faster machine is underway. The current foils are suitable for speeds up to 80 km/h and, in cooperation with Fakulteta za Energetiko (Faculty of Energy Technology) in Krškothe, the company is developing its own outboard motor and propeller with variable pitch which it believes will be one of the most efficient in the world. The propelor and 12 kW outboard will be ready later this year, presumably meaning that a version will be available in the not-too-distant future with a top speed more than double the current version.

From a recreational craft through to a silent, fast craft for special forces, the Quadrofoil looks to have every chance of commercial success. Distribution, dealership and investment inquiries will be welcomed from all countries according to the company. Source: Quadrofoil

About the Author
Mike Hanlon Mike grew up thinking he would become a mathematician, accidentally started motorcycle racing, got a job writing road tests for a motorcycle magazine while at university, and became a writer. As a travelling photojournalist during his early career, his work was published in a dozen languages across 20+ countries. He went on to edit or manage over 50 print publications, with target audiences ranging from pensioners to plumbers, many different sports, many car and motorcycle magazines, with many more in the fields of communication - narrow subject magazines on topics such as advertising, marketing, visual communications, design, presentation and direct marketing. Then came the internet and Mike managed internet projects for Australia's largest multimedia company, (Australia's largest Telco), (Australia's largest employment site),,, and a dozen other internet start-ups before founding Gizmag in 2002. Now he writes and thinks. All articles by Mike Hanlon

DB9 for the roadways and the new Quadrofoil DB10 for the waterways. I definitely can Bond to this.

Flipider Comm

A swimmer could be instantly sliced in half if struck by one of those serrated edge foils at 25mph. Otherwise the design seems brilliant. So what can be done to improve safety?


not driving over swimmers will improve safety, just like not driving your car over walkers.

David Anderton

Cut the price in more than half by using Basalt or a high end glass. Carbon may be lighter a little but the price is way too much and it shatters on impact. Basalt is 4-5 times less expensive and UV immune, impacts better and does NOT conduct electricity. Nice ride!


re; Alien

The blunt little bumps that greatly improve the efficiency of the hydrofoils do not make them more dangerous. If you do not want to get hit while swimming stay in the swimming area.


I like it! Not sure about the range though-68 miles translates to how much "fun" time before it runs out of juice? With other PWC's you just throw more gas in it-

Robert Volk

Hate to think that our Editors here at my favorite eMag/newsletter are gullible enough to repeat things like "By comparison, most Personal Watercraft with the throttle wide open will burn a liter of gasoline per minute". NO ONES b.s. sensor went off? are we supposed to belive that "MOST" pw's blow through a ten gallon tank in less than forty minutes? COME ON! swallowing that just cheapens what--in the balance-- is really a pretty good article on a neat bit of technology that can be applied to lotsa things like lower hp bass boats and stuff. No body idles a pw around all day--its full throttle baby! And the fuel lasts quite a bit longer than 40 minutes. :)

PicklePop Flyer

I looked at this one and all of the related hydrofoil stories - Where's the video for something like this?


Back in the day I recall the local authorities used jet-skis to patrol the San Joaquin River delta (California). The Quadrofoil might be an improvement. An efficient IC engine (4-cycle?) with a good muffler and a decent sized fuel tank would allow the Quadrofoil to stay out longer, and return to duty (or frolic) quicker after refueling, all the while not beating the pilot half to death (but maybe that is part of the fun). The occasional barely-submerged tree branch may do some damage to the foils, but swapping out one or more doesn't appear to be a major effort.

Bruce H. Anderson

Hmmmm... let's do some maths: Presumably the top speed is at full power. A 4.5kWh battery pack will be completely drained by a 3.7kW motor in about 1.22 hours. Multiply that by the top speed of 40km/h and you get a range of around 46km (That's assuming the battery is still able to put out full power until the last moment, which is doubtful). Reduce the power consumption and it will take longer to drain the battery, but it will be going slower as well. I personally doubt that there would be any worthwhile speed at which it would achieve the stated range.

It would be more believable if there were photos of it in the water, and if a "range at full speed" figure was given, and a "speed to achieve maximum range" figure, which would indicate honesty and completed research rather than just an "advertising claim".

I would be VERY happy to have my doubts proven wrong, as I believe that electric vehicles will be forming an important part of our transport future, and performance and range as claimed would indicate the possibility of economical, quiet, ecologically friendly and efficient transport. Also, this looks like fun!


re; jerryd

If you swim in the boating areas and get hit I have no more sympathy for you than I would for the dammed fool who tries to walk across a busy highway and gets hit.


What happens when you hit a floating stick at speed?


I live right next to a lake. If this were 1/3 the price, I might consider it (though I'd prefer a submersible PWC of the speedy & finned variety).

Joel Detrow

Slowburn, don't tell me where to swim. It's my right not to get hit by the fool who buys one of these death traps.

It shows that just because new tech allows one to invent things doesn't mean they should and this is an excellent example.

Please tell me just what happens when this runs aground? One would be pitched head over heels ino the water with the boat flipping over on top of you. Sounds fun!!!

Do you think there is nothing in the water? It's loaded with old tree parts or even whole trees, dock pieces, metal drums, various kelp, grasses, etc. Just hitting any of these would ruin your whole day.

This is what happens when people who know little try to do things.

As a side note the US 138' long 3" gun, Harpoons, Hydrofoil gunboats from Key West one day hit a whale and destroyed the whole front end, foil and sent the full crew to the hospital. whale didn't have a good day either.


re; jerryd

Running aground is an act of gross stupidity. As for other submerged objects it probably is not as dangerous as driving. Just because you don't want to accept the risks does not mean that the rest of us should not be able to.



What's protecting you from "fools" who drive personal watercraft now? Would you be safe if a jetski slammed into your head while you swam? Would the propeller of an outboard motor cause no injury?


Has it gotten wet, yet? anybody know?


no videos on the site... although there is a video section, it has no vids.

vapourware? Does the mockup even float?


Great design!! Now make something of it that more peolple can enjoy it! rip the engine off, make it lighter, keep the foils and the bottom part, lower the seat height,make it a single seater and adapt it to sail with a kite like the ones used in kiteboarding!! Now that a clean, ecological pwc!! last but not least, make it cheaper! I sure would buy one!


@ Joel, This is not the first boat to have hydrofoils. How do you think they cope in the oh so dangerous seas!? The Quadrafoil self rights so it will be a bit painfull if you get flipped, but you wont drown. Trees and oil drums and vegitation and ropes cause problems for all types of watercraft. Designated swimming areas are there for your safety. Dont swim in them if you dont want, but dont complain that someone else or something else is using the water and you get hurt. Looks like the Quad could be alot of fun. Can see it being used at resorts first, especially as an alternative to Jet Skis. @ David Anderton Would Basalt be strong enough for the flex required with hydrofoils?


PMJ - gotta love yr idea. Just saw the sail/kite that Aussie dude has invented, could be a goer.

But it really needs to be enclosed so it can dive, that's where the fun would be.

By the bye, I saw those fins/foils on a previous edition of Gizmag, invented by a whale watcher dude in the US, he had a patent on the design. Wonder if these guys got a licence?


From seeing the website, the idea looks like all it is. Testing will prove that in the real world, the numbers will be no where near their claims. Even good impellers get near 80% efficiency, with a 3.7 kW motor I don't see this being near as exciting a ride as envisioned. I'll wait until I see videos. Unitl then it looks like they are trolling for investment.


There is an emergency medical solar tentmaker in Texas that would likely build something foldable in a solar charger for this vehicle. It would work in either a temporary fashion, or to trickle charge a backup battery. No need for fuel for the life of the vehicle.


I seriously doubt 3.7KW is anywhere close to the needed power for this vessel to become foilborne. Prior to the craft "lifting off" it must break the surface tension on the primary hull. With 2 people onboard it would likely putter around at about 6 kts. At least you will look "cool" while doing it...

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