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Wow! e-Foil, ultimate low wind...How does it work?

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tahoedirk
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Re: Wow!!! e-Foil , ultimate low wind.. How does it work?

Postby tahoedirk » Mon Oct 24, 2016 5:22 pm

I ,for one, am definitely living in an illusion. Not a bad way to roll.

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Starsky
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Re: Wow!!! e-Foil , ultimate low wind.. How does it work?

Postby Starsky » Mon Oct 24, 2016 5:38 pm

Will work for real surfers first, Those who can paddle into a swell to help the motor out and hop up to standing.

Inlanders you'll will need a winch, bungee or tow.

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Re: Wow!!! e-Foil , ultimate low wind.. How does it work?

Postby Jzh_perth » Tue Oct 25, 2016 5:21 am

Starsky wrote:Will work for real surfers first, Those who can paddle into a swell to help the motor out and hop up to standing.

Inlanders you'll will need a winch, bungee or tow.
Just wondering about the power requirements for an eFoil. Considering Kai Lenny can paddle his foil surfboard sufficiently to get riding, perhaps the power requirements are much less (when there is a following swell perhaps). Robert Forstermann the german track cyclist "only" puts out about 700-800W as a sustained effort - I'm referring to the video when he powers a toaster enough to toast a piece of bread. A human paddler would be outputting much less. The Wavejet surfboard produces 20 lbs of thrust (2kw i believe) and is sufficient to propel a surfer along at 10mph apparently.

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Re: Wow!!! e-Foil , ultimate low wind.. How does it work?

Postby joriws » Tue Oct 25, 2016 8:19 am

I am more wondered that he can pump foilboard from wave to wave while standing. Meaning that much power cannot be required after getting planing. But I think efoil's key issue is to get flying including all the mass of platform - after flying you can continue ride with little power.

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Re: Wow!!! e-Foil , ultimate low wind.. How does it work?

Postby Starsky » Tue Oct 25, 2016 11:29 am

I can't see a board getting enough power to get flying on flat water without being an absolute tank. It looks like that is the end goal of products like the Jetfoiler shown on the first page of this topic. Push button skill level only marginally tougher learning curve than a jetski. Lame, mostly straight line riding in near windless conditions. Pretty anticlimactic to anyone who has experienced the maneuverability of foiling with a kite.

I can definitely imagine a much lighter and lower powered but workable set up that requires either a tow up or a wave in order to get flying. Something geared specifically for the power range required for sustained flight. The motor is only an assist and I would imagine a board primarily designed to ride swell rather than flat water cruising, but who knows, maybe there is some fun in it for the cottage at the lake crew! Something that perhaps only turns on once the prop is actually turning at a certain speed due to assist, be it wave or tow. Then once on its just on, no hand throttle, just an assist to keep you flying back out to the line up. Rider would have to be skilled at not bogging, losing speed, and dropping off the wing. As a bonus, while riding faster than the normal cruising speed of the prop, it could charge the battery.

Not as commercially viable as the skill requirement is still very much there, more of an electric assist than outright powered foil. Could be incredible for talented surfers and make many more people feel like Kai.

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Re: Wow!!! e-Foil , ultimate low wind.. How does it work?

Postby Europ2 » Wed Oct 26, 2016 1:33 am

Jzh_perth wrote: The Wavejet surfboard produces 20 lbs of thrust (2kw i believe) and is sufficient to propel a surfer along at 10mph apparently.
It seems that both power and battery voltage escalade are very likely to occur.

Found in the general performance specifications of the 2016 WaveJet Model A power pod:
• Maximum thrust: Model A: 20 lbs
• Minimum run time: Model A: 30 minutes of continuous run time
• Re-charge time: 3.5 hrs

• Nominal voltage: 21.6 volts (V nom)
• Nominal capacity: 27 amp-hr (I nom)
• Nominal Watt-Hour: 583.2W (= V nom x I nom)
• Normal voltage operating range: 19.5 to 24 volts = 21.6 +/- 11%

So 583 W <=> 20 lbs OR 9kg of thrust can supposedly move a 80 kg mobile over the water at
8knots for 30 minutes wih Lithium Ion batteries, a longer run time if you accept 5 or 6 knots.
Obviously, it's not the type of performance we're after.
At least twice this power combined with the HF performance factor (minimum wet surface) should allow to reach approximatively 2 to 2.5 times this speed.

So choosing a minimum power of 1.5 KW seems to be a reasonable tradeoff and a good start, that is 12-15 knots for 45 to 60 minutes run-time. It's just a guess.

There is a lot to learn from the e-surfboard world. They use Li-Ion batteries to maximize the very short run time....Although the lithium-ion polymer (LiPo or LiPoly) battery is sleeker, thinner (10% better energy density) and very popular in the R/C world, lithium-ion batteries cost less to manufacture.
The Carver board from aquilasurf.com = onean.com (Aquila group) , 4400W Water JET, 19 to 22 knots for 20 min max depending on water surface , rider 80kgs
http://www.onean.com/producto/carver/#products - cost 5000eu incl VAT

see also:
http://www.radinn.com
http://www.waterwolf.de they have the type of water thruster we're after !!
Waterwolf  MPX'3.jpg
Waterwolf MPX'3.jpg (21.38 KiB) Viewed 1348 times
The extreme in terms of power and price:
The Boost board from lampuga.de from Hamburg, 11Kw (15HP) water Jet, claims 34mph or 30 knots during 20 min, 52V Li-Ion battery and cost €13.000 or €18.000 if carbon Edition !!
http://lampuga.de/product/lampuga-boost/

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Re: Wow!!! e-Foil , ultimate low wind.. How does it work?

Postby DrLightWind » Wed Oct 26, 2016 6:26 pm

Europ2 wrote: http://www.waterwolf.de they have the type of water thruster we're after !!
55 lbs weight and 15 Kn /maximum speed for less than half an hour is boring and $10K is expensive. :wink:
I don't think you could really minimize the weight and 5 kW power expenses of an HF with our "Techno-Logic",
especially when you'd like get a decent 25 - 30 Kn speed, where the fun starts. :lol: :nono:

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Europ2
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Re: Wow!!! e-Foil , ultimate low wind.. How does it work?

Postby Europ2 » Wed Oct 26, 2016 9:25 pm

DrLightWind wrote: 55 lbs weight and 15 Kn /maximum speed for less than half an hour is boring and $10K is expensive. :wink:
I don't think you could really minimize the weight and 5 kW power expenses of an HF with our "Techno-Logic",
especially when you'd like get a dissent 25 - 30 Kn speed, where the fun starts. :lol: :nono:
DrLW
http://newatlas.com/waterwolf-electric-surfboard/30597/
A cool but very expensive gadget indeed. For 30kmh / 16 knots max only .... The battery ....50% of the board weight ....
Waterwolf-Exchange Battery MPX-3
Price: 2.590.- € (incl. 19% German VAT)
Voltage: 51.8V (nom) (max. 58.8V)
Capacity: 34 Ah (~1.9 KWh)
Weight: ~ 13kg
Runtime: 35min ~ 40min (range: - 10 km)

***
Power: 4 KW (max. 5.5KW)
Board dimensions: 239cm x 65cm x 13cm
Volume: 100l
Weight: ~ 26kg with battery
Charging time: approx. 3.5 hours
(With quick charger: 1.5h - max. Approx. 2 1/4 h)

Then, It is difficult to evaluate the efficiency brought by the Hydrofoil. After the waterstart which requires to move rider AND board weight (no or marginal gain during those 3 seconds) can we expect at least 15% of drag decrease during the flight ? ? This would increase the battery runtime by the same factor.....
If the answer is no, a home made surfboard with waterjet will be easier to make and probably less dangerous to use.

For less than 300 USD on one of the links here https://www.youtube.com/results?search_ ... 0surfboard

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ozonelevel
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Re: Wow!!! e-Foil , ultimate low wind.. How does it work?

Postby ozonelevel » Mon Jul 03, 2017 1:11 am

Just get a Scubajet and duct tape it to your hydrofoil: http://www.scubajet.com/
Last edited by ozonelevel on Mon Jul 03, 2017 12:28 pm, edited 1 time in total.

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Re: Wow!!! e-Foil , ultimate low wind.. How does it work?

Postby Blackrat » Mon Jul 03, 2017 6:38 am



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