E-foil with water jet instead of propeller?

Just thinking outside the box here.

I have just finished building an electric surfboard (not a foiling board) (video of 2nd run here: https://www.youtube.com/watch?v=81WGsLw6IYQ ) and have absolutely no intention in building a foiling board as the place we use the board has lots of water plants making it impossible to foil (even the big boats have problems with them).

The jets (the board has 2) has unbelievable power. In the video the jest are running 1/2 power).

So… Me thinking… Did anybody ever tried using a water jet instead of a propeller as propulsion?
I am sure that a jet and motor will not be much bigger than what is being used now, and it could easily be made into a hydrodynamic package.

Also a jet (pump) efficiencies is around 90% or more than a conventional propeller (60%-72%)

Any thoughts?

How old are you?! Nice job!

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I am 12. And my dad did help me with the build.

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Yes has been done.


But Jets compared to props have lower eta.

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hmmmm okay. this thread can now be closed. :slight_smile:

90% Eta is Utopie for Jetdrive, Sorry !
Greetings Frank

Hi Frank,
According to this data they are Waterjets: When to Use, Pros and Cons - DMS Marine Consultant

3.0 Efficiency
A waterjet is essentially a pump inside a very short pipe. Pumps work differently than propellers; they don’t show the same limits. Pump efficiencies around 90% or more are regularly attainable. In contrast, conventional propellers stop at 60%-72% efficiency. But waterjet efficiency involves more than just the pump.

You must also read correctly …
In addition, a prop drive with shaft and rudder serves as a comparison …
Then there are completely different diameters in use.
The smaller the jet, the more difficult it gets.
Compare a 250hp jet ski with a boat of the same weight and power …

What are the jet thrusters you are using on the board? How much power output do you have at 1/2 power?

The jets used are Youngster jets and I do not know the power output but soon my dad and I are going to set something up to measure.

Don’t be angry with me, but youngster jets are nice, but far from effective.
It’s not that easy with the jet drive.
The larger the diameter, the more useful for Eta, but still no comparison to a well-coordinated propeller.
Compare the data and performance of good efoils with well-known jetboard manufacturers. An Efoil provides only 30 to 50% of the power for the same speed. The situation is similar for boards without foil, but with propeller (Waterwolf)

Greetings Frank

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Why would I be angry? The board for me is working perfect.

To perfect actually. I was hitting the 32 km/h mark today, and this is way to fast for a board like this.
The board starts to rock from side to side… no fun… So. my dad tuned the ESc’s down…

Also. When a boat / board / jetski goes faster than 20 km/h it needs what we call here in the Netherlands a Y number and insurance. The driver also needs a VB2 license (same license to steer a speedboat). You can get this license from 18+

I’m 12, and officially not allowed to go faster than 13 km/h…