It’s not using a flexible shafts! They using two diesel engines to drive two electric motors.
Straight from their website:
“The FOILER has a hybrid diesel-electric propulsion.
The two inboard engines drive two generators providing the electrical power.
Two electrical torpedoes deliver the power that then propels the boat.”
That’s their prototype, and you can see on the video, the hydraulic lines going in the rear foils to the hydraulic transmission. I guess the overall efficiency wasn’t too good, that’s why they are going with a hybrid gen/elec
They tested this craft on the Geneva lake a few years back
The first prototype used indeed an hydraulic transmission. It was super noisy and not as efficient as an electric drive system.
Now, they are using 2 electric pods and the electricity comes from 2 motors (from BMW I think).
Six cables:
1 and 2 hydraulic power ?
3 and 4 hydraulic command (forward / reverse) ?
5 coolant ?
6 thin electric cables for probes
Maybe 3 & 4, is for the trim?
Has anyone here got more experience with hydraulics? I have none. I am wondering if you could have a 70mm hydraulic motor underwater and power it with 8mm diameter tubes from the board. Would be awesome.
… IMHO it is quite possible to implement this solution at the 90° angle from mast to pod. However there might be a possible heat exchange issue between the three flat cables. Round is beautiful 
@Gobbla Would you mind sharing details or files of how you implemented the wire duct. It’s always nice to see how others do it before I get distracted by my own horrible ideas 
For instance, I’d be curious to see if you used a key to connect the various 3D printed pieces together…or how the assembly/bolts were arranged in the nose…etc. Thanks. Trying to experience with this approach to ease myself into more builds in the future.
Hello, just back from holiday, I will try to share files this week.
I have test to pass cables in the mast, disappointing, no gain in electric consumption
This is sort of where I’m heading based on some stolen ideas Looking forward to seeing what you’ve been thinking.
@mkefoil Nice work . You may also want to consider this design Flipsky/ Maytech 65161 propellers for sale - Props & Ducts - FOIL.zone
Thanks @theone The prop end is where I still have the most to learn. I’m also pushing design parameters so that I can print everything myself here on my smaller print bed. So I’m going to have to go a little smaller in diameter to fit everything (especially if I don’t want to go open prop). The one in there is an enlarged version of something that started with the parametric design I found here. I’ll go through the whole java prop process and see what I come up with there that fits. Hopefully finding a decent compromise.
STL file :
Nice mast clamp 
I think this pod nose that you screw on the front clamp body is underestimated and the way you hide the mounting screws is very clever. 
thanks, dont hesitate if you want solidworks model , to improve it.
if you need small modifications i can do it
How wide is your prop duct?
I need one for a 195mm aluminium prop
Unfortunately I haven’t gotten back to the duct. That’ll be a summer project with tests in the water. Mine was just too beefy and caused too much inefficiency. I also abandoned the shroud and ran the cables up the mast. Not because I had any real problems with it, but once I got a more dedicated board setup (not using my kite foil board), it just became less complicated that way.
As an aside/update @SoEFoil: I thought I was clever and went that way too I also ran my cooling line through the screw on cap. In case that’s helping anyone here. All fit in a Slingshot mast actually and helped to make use of the front cavity. Happy with this aspect for sure.
An included water inlet in the screw ? Huuuuu it is truly cool. Congrats Mke ! Looking forward to more 3D views and to it becoming real. Hey @Gobbla what do you think ?
I hope you won’t mind guys but, I would be really happy if a foil pioneer company like @Mantafoils was launching the first retrofit efoil kit that preserves the mast integrity (ie no drill) with such a cool feature… at a DiY price of course ! … There would be a mast compatibility problem to solve as there are different chords and thicknesses on the market. Possible solution: ala @Rienk solution (not soft today), a kit with different spacers (hard or soft) could fill the gap between pod nose and motor.
Forced watercooling of the ESC above the mast plate from the pod screw nose ! 
The simple, effective and aesthetic solution of the people for the people ! I just hope that sbdy will not patent this.
