Efoil convertible in a esurf

Hi to every one,
I would like to share with you my first build.
The idea behind this project was to obtain something different from what was in the market.
In order to build a board that could be used by all components of the family, I tried to do something easy to convert. In this case is enough to unscrew 4 screws and put a cover instead of the hydrofoil mast and you can change from efoil to esurf.
The main drawback is the weight. Esurf needs a powerful motor (14 kw) that works at high Amps, so the battery became very big (3,8 kw) and heavy.
The project isn’t completely finished but, at this moment, I can’t work on it, so I show you as it is.

Here the video:


For more photo https://www.facebook.com/media/set/?vanity=1037723882917113&set=a.2934685689887580


Very cool carbin fibre work. It´s a pitty the jet drives waste that much energy :roll_eyes:

Your composite and molding work is outstanding! Nice hybrid craft, congrats!

I’ve seen this video before. Does it work? I only see you foil for a couple of seconds. Does the waterjet push enough when only in the air?

I love your carbon work, and I hope to be 1/2 as good with working on carbon as you one day.
At this moment I am only good in making a big mess with carbon / fiber :frowning:

And I am an esurfer (jet boarder) and yes. it does need a lot of power.


Of course many of us have watched you for a long time and lots of us have high praise for you excellent work. I’ve seen your videos referenced many times in public & private forum.

As @Kian asks, there are several who have questioned how well it worked?

In the first time decided to do two video, the first for the construction, teh second with the trials.
Unfortunately I had some problem between the esc and the motor (and still remain…) so I don’t have enough material to do the second video. I’m waiting to work on it and do better points of view.
The right way to work for the jet is free on the air. You don’t need that the water flow touch the water.

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Nice to see you here , a big fan of your work , and thank you for answering my questions ( on another forum )

I hope you can find a way to work things with your esc, you can switch to trampa 75/300 if needed , more info available for this one

Thanks, truly speaking I used it a very few time, so Is very difficult for me to give you a complete answer.
And, every time I had a problem that limits the trials.
At first I had some problem with the connection between remote control and receiver, every time the board was submerged the signal was lost.
In the second time I destroied the waterjet (I replaced it with a bigger one)
Last problem is that when I put more than 80% throttle the motor stops…

So it is very difficult to say if the concept works or not (the other problems are common with standard configurations). For sure, when I started the main question was " Is feasible to feed the waterjet trought
the foil mast? I’ll be able to do that resistant from a mechanical point of wiew? … Ok, on these questions I can answer YES!!! :grin:

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I’ve already bought a trampa… but for the new efoil :sweat_smile:
Surely I’ll ask some info about the right setting because I’m terrible in electronics

That’s some impressive work, good job!

The higher the jet stream is above the water the harder the motor will have to work to lift the water up then accelerate it out the nozzle so I guess it would not be that efficient when the stream is high above the water (when foiling).

Will you try it as a normal jet board? And what is the diameter of the jet?

And what motor did you use?

Discussed here :

Pretty sure the Scorpion 7455 motor.

EDIT : tried several times but link won’t point to the related thread…

@Brucecreations Nice work by the way. Exceptional composite talent you have ! We’ve been following your porject sinds the very beginning :wink:

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Unfortunately I used MHZ – Scorpion 7455-320 KV motor

It’s true but you have to consider the speed (take off around 12 knot) and the inclination of the foil mast. I can’t do a correct evaluation but I suppose that this loss is compensated by the pressured water that comes in. The section of passage has a light but continuous reduction (I was afraid of cavitations). You must also consider the fact that when the foil is near to the surface the loss due to the turbulence are near at standard kitefoil configuration. In the standard configuration with motor, propeller and his cage, you have a lot more resistance.

I tried the board first as jetsurf. With 64 mm jet the acceleration is poor, with 80 mm is OK

I’m sorry… I didn’t noticed. :face_with_hand_over_mouth: For the administrator, please remove my post if you want.

Yes that would help a lot! I guess the price you pay is the drag required to force the water up from pressure at the inlet.

Like Alexandre mentioned you should try putting a VESC 75/300 in it you’ll then be able to tune it so you have full motor power and it won’t lose sync when tuned properly. I think a good ESC will make it much better to ride!

Was the motor overheating at all? Is it cooled by water flowing through the core of the stator like other water cooled out runners?

I believe the 7455 was made for MHz with a water cooling included in stator plate , no sure it is enough to cool it But it is to nice to see it is strong enough to turn the 80mm
I don’t why MHz keeps selling the 64mm kit with this motor , I think 320kv gives low rpm to this impeller at 12-14s , especially with the voltage drop on 18650 pack , many complain about this problem

[quote=“jakebarnhill1, post:16, topic:10756, full:true”]
Like Alexandre mentioned you should try putting a VESC 75/300 in it you’ll then be able to tune it so you have full motor power and it won’t lose sync when tuned properly. I think a good ESC will make it much better to ride![/quote]

The main problem is that for this motor 400 A are required so I choose an industrial version of MGM (more than 1k euro) but something went wrong and both Scorpion and MGM didn’t give me an answer.!
I tryed all the possible configurations but the problem remain.

The motor has dedicated cooling circuite

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I am not a expert but check lehner motor web site and its motor calculator , they have a motor close to the 7544 with no water cooling

It will give you the correct number , like something around 8nm of constant torque and about 200A of efficient power (?)

All other number are pics or max for a couple second before it burns, you can draw like a 1000A or way more before it stalls but it doesn’t mean you will have the mechanical power

22kw at this kind rpm , specially from outrunner …
more like a real 11kw for his application

After everything will go out of control , that is probably what happens

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my experience as well with this kit. 64mm is too small, 15s 18650 has significant voltage drop at 200A and can not get 80kg human on plane with the 130L MHZ board. Quite dissapointed at MHZ since its a 5000€ pack without batteries…

Hopefully the 80mm is more suitable, but I would never build with Jet again. If I’m ever doing esurf again it will be with prop.