JET BOARD PROJECT

Boats, Jet Skis, Kayaks etc., including hovercrafts
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j.o
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JET BOARD PROJECT

Post by j.o » Jul 27, 2016 1:31 pm

Hi

I would like to build a jet board for my family. I have an old surf board and would like to mount on a propulsion system with electric motor and battery
Can one buy a DIY kit?

Board requirements:
1) carry weight of about 80kg
2) speed of up to 30 km\h

Does anyone know how to calculate the propulsion system, electric motor and battery sizes\types needed for this project

I would be grateful to get some direction or tips on the matter.

Thanks, J.O.

bbq870
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Re: JET BOARD PROJECT

Post by bbq870 » Oct 01, 2016 1:28 pm

there's plenty of research.
you should go on YouTube and watch everything, what floats and has an electric drive. get all numbers available. (power, speed, weight) whatever you can find.
then you should have a rough guess of what your vehicle will need.
also check engines with gasoline. once you have the horsepower and cc you can easily convert that into Watts for electric motors.

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recumpence
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Re: JET BOARD PROJECT

Post by recumpence » Oct 01, 2016 5:22 pm

I built one wakeboard for a client last summer. I found that 20 to 22 knots with a 180 pound rider we needed 10,000 watts for innitial acceleration and planing out, then it settled into 7,000 to 8,000 watts continuous to cuise. Also, we had a 12S lipo pack that was 16ah and we got around 13 minutes run time.

Bear in mind, this is NOT an easy project. I burned up 2 motors and 3 controllers figuring this out. Lots of math, lots of experimenting, lots of time, LOTS of money.......

I ended up liquid cooling the motor and fan cooling the widings to get it to survive (This was pushing for 30mph). 20 knots is not nearly so difficult. If I try it again, I will go for two motors and two controllers to spread the load and heat over more components. Also, wiring...... You have to run very substancial wiring. Water is a constant load on the electric system. Pulling 150 to 210 amps continuous is EXTREMELY difficult to properly wire for.

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dirkdiggler
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Re: JET BOARD PROJECT

Post by dirkdiggler » Oct 10, 2016 11:56 pm

The Chinese are using 72v at 7500 watts in their surf boards. Nice to finally see some figures on what it takes to get a board on plane and what the speeds are. A tough project for sure to get everything right. It was too hard for me to take everything down to the lake and have something not work right, then have to drag it back home, fix and do the same thing over again. Finally realized this wasn't the project for someone with my knowledge! Exactly lots and lots of time, money and props. A few batteries in the process. Always figured it was the gearing - being the wrong size props. My RC boats blow through batteries just like that.
I'd imagine with a foil board you could use half the watts to get similar speeds. Never ridden a foil, but with kiteboarding they are getting the same speeds as boards using much bigger kites. A lot of math in those calcs, but a foil might be a better idea.
The specs will all change though depending on your weight and the displacement of the board. There isn't much info out there on this. The Turnigy 80/100 motor on 12s with a 1:5 reduction seemed to get a 160lb guy up and running at about 20mph. That was using the same prop as Waterwolf. Other than the expensive German boards and the Radinn which is Dutch?- there isn't much to go off. They all seem to use a proprietary jet drive that is custom designed.
The efoil board from the Silicon Valley guys has no know specs at all. Even there drone footage is pretty discrete on what is powering it. I have yet to see any images of how their system works or what it looks like. Coming from a Silicon Valley startup though, I don't have any hope the pricing to be reasonable. Especially given that foil boards with out a motor are in the 1500 dollar range. I'd like to see them suceed though, I remember him from the kiteboarding forums a decade ago. He had some cool ideas for powering tankers with kites and we had some discussions on using kites for power generation instead of fixed wind vanes. I think he shot down my ideas, but I did read a few days ago about them doing exactly that in the Netherlands. Power kites generate at 10kw to get you up on plane!

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Bazaki
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Re: JET BOARD PROJECT

Post by Bazaki » Oct 12, 2016 2:47 am



You have seen this ?

Indeed much less power needed for good speeds.


Where did you see specs of chinese 72v jet boards ? I'm curious too.


Ok I find them now by searching, 72v jetsurf.
https://www.alibaba.com/product-detail/ ... 92201.html

No real pics, only fake pics.
Too risky to order I believe. Maybe some day we can see real video's of the chinese boards

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Re: JET BOARD PROJECT

Post by dirkdiggler » Oct 13, 2016 10:34 am

Here's a vid from the Chinese company. I put the video in the main surfboard thread. The video make it look a bit slow. They don't have product available yet. They mentioned there were having some issues with the board. Might have been blowing up controllers? I'd be willing to travel and try it out before I actually purchased it. Too much cash to buy something like that on a whim. I imagine the jetfoiler will be in the double digit thousands.

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Re: JET BOARD PROJECT

Post by Bazaki » Oct 14, 2016 8:48 am

Thank you for the video. I think the board must be wider.

There is this video where a drone is pulling a guy on a skimboard, also at deep water. I also see skimboard videos, where they can plane very long also at deep water when they ride the board sideways. Which also made me think that a wide board gets better in plane.

I will look up a video

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Re: JET BOARD PROJECT

Post by recumpence » Oct 14, 2016 9:48 am

It looks like other people have found the same numbers I found (7,000 kw or more) to run a wake board. :mrgreen:

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Bazaki
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Re: JET BOARD PROJECT

Post by Bazaki » Oct 14, 2016 11:09 am

I also found out that when running my kneeboard behind the winch takes much less power when riding sideways.

A skimboard is almost flat with on top a bit of rocker shape.





For example video at 50sec and even better at 1.24 minutes!!
That is deep water, so no ground effect like normal skimboarding

He holds the board sideways and can plane extremely long. With a kite board kneeboard or wakeboard you will have much more drag and will sink after a few meters. So holding a skimboard sideways will make it a very short and very wide board with no rocker that can plane with very very little power. True ?

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Re: JET BOARD PROJECT

Post by Just2807 » Jun 27, 2017 7:49 am

Bazaki wrote:Thank you for the video. I think the board must be wider.

There is this video where a drone is pulling a guy on a skimboard, also at deep water. I also see skimboard videos, where they can plane very long also at deep water when they ride the board sideways. Which also made me think that a wide board gets better in plane.

I will look up a video
Well, as a kitesurfer, i can tell you longer and (more importantly)wider (with no, or almost no rocker at all) are planning champions and are suggested for beginners (easier to stand and less speed needed to plane). Drawback is less maneouverable and a bit*h in chop. Once they learn how to board, they dont throw it away, they keep it for lightwind days (slower wind). I am talking about twintips, got no experience with surfboards.
I saw few people on some hybrid surfboards with foils attached. Usually they kite with 2-3 square meters smaller kite (nice amount of underpowered) cause ofc they need way less wind/power (less resistance in the water) to keep the speed and float. So bigger buoyancy, bigger width, better it will perform with less power. Since different weights and shapes (and ofc no linear wind as a power source) are involved, there is no "golden shape and standard".

Nothing special here but its getting massive around the globe!
https://www.youtube.com/watch?v=TYeniBWNaW0

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Re: JET BOARD PROJECT

Post by ecycler » Aug 02, 2017 2:17 pm

...just when I thought 'poledancing' had all but died, there are some guys who bring foils into the mix to bring a small, fresh breath into the sport! :wink:
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Re: JET BOARD PROJECT

Post by recumpence » Dec 08, 2017 5:36 pm

I have had very good success with a six foot electric wakeboard. I cannot tell you the specs because it is an OEM project for a client. However, I can tell you it is explosively powerful, runs over 30mph, is relatively light weight, and good for over 20 minutes of run time per charge.

It is possible to build a board like this, but I can tell you it is extremely difficult and expensive.

You can expect to see a number of water EVs come to market over the next couple years.

Matt
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