I left the original one in place and extended it with the new one. Used shrink wrap in both the individual cables and then for the the 3 wires together. Don’t know how watertight the union is, but so far it seems to be holding just fine.
Build finished. I added a heat sink to the esc to allow for sustained runs without overheating.
I also added 3dp trailing edge to cover the cables, which has the same airfoil as the mast. Dont know if it makes a difference but it looks cool.
Top speed is 20kph using a gong veloce 1900cm2. Preliminary efficiency with lots of water starts is 80 wh/km
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Links to thingiverse added (freeCAD)
EDIT : it seems the freecad file for the motor pod is still being processes and not yet available for download
Have you got a close up of the seal you used on the Explorer box? You are right, this thing leaks like a sieve with standard seal… Tried a standard window seal I had lying around and it was a little better but still letting water in.
When i added the heatsink and checked again for leaks i found some drops. Seems this material is similar to a memory foam.
So i increased a bit the thickness by cutting another profile horizontally and adding just its base, below the original profile. Now it’s watertight again.
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Nice for the stator I did something similaire. I used the lexan cover for an old manual, I put some wax on and I warp it with rubber band… I had hared time to remove it. Next time I used your technic 
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Hello, are you still using this prop? What do you think about using it on 8S on 6374 motor?
Just exploded my PA12 michhobby prop so looking for a replacement to print
The prop was designed to get max thrust on 6S, no idea how efficient it was but worked ok as an assist. Now I switched to 12S and using the most popular folding prop i found on the site. So far working good. (cant remember the creator , but should be easy to find)
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About reed switch. Would you explain please what problem does it solve?
So 6s did not provide enough power?
How does it feel now with the 12s?
But you have high kv motor, how does it get along?
About reed switch. Would you explain please what problem does it solve?
The goal is to turn off the motor if I fall from the board. Originally it simply removed the power from the Rx, which meant the ESC had a latency of 1 sec or so to reduce the power to zero. Now I’ve added an arduino between the rx and the esc. If the reed switch is connected, it sends the rx signal to the ESC. When the reed switch is disconnected, it overrides the rx signal and sends a 1ms signal to set the power to zero immedieatly. Or you could do something similar with a RC failsafe, someone in the forum was using one
So 6s did not provide enough power?
How does it feel now with the 12s?
But you have high kv motor, how does it get along?
6s with the KV I had was working perfect as an assist. I just wanted to try something closer to a “real” efoil, so i bought a new 120kv motor. It was fun and has higher speed, but honestly I havent used it much. If I had to build a new assist now, I’d go again for the 6S and high KV motor. With 6S you can even use RC chargers, which makes life easier ( or maybe 8S to reduce losses?, back when i built it i didnt know there were cheap 8S ESCs ) .
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But if you fall from the board, first of all you probably release the remote trigger. And when you are in the water the receiver looses communication and so turns off the motor. Isn’t this is how it is working?
It is very important to you - to turn off asap - why?
that’s the theory, but:
- sometimes when you fall you forget to release the trigger. In fact a kid lost his thumb when he landed on the prop.
- once the tx is under the water, the rx will no longer receive the signal and will keep for a second the power commanded in the last received signal.
In fact , the alternative to adding the Arduino, if you are using BREmote for example, it probably has spare pins and the soft can be updated to what your Arduino doing…
Could you take a picture how the leash actually attaches to the box, board and feet.
What is the actual performance - when the relay activated ? When human in the water or when feet outside of the board?
If BREmote has accelerometer, it could maybe detect free fall and send disconnect.
Of course it is not that robust.
The leash is direct mechanical disconnect sent directly to the box, so it is great! And solves the impossible to solve first problem disconnect despite person keeping the trigger pressed…
the leash attaches to the red part with the magnet inside , it’s held in place just by the force of the magnet. The leash is just a very short string that goes to one of my feet. As soon as I pull it, it will send the signal to 0 power
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Yes, I see, clever.
But have to put the magnet in place each time you fall 
. When learning it is tedious, no?
Hi @pablo_foil, great build! do you put the snap ring + golden washer back on the shaft (or leave them off like FD) and where do you cut the shaft? Thanks a ton!
I read a couple of comments saying they lost the bell, so I kept the ring for safety. What’s the goal of making it removable?
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Thank you! I believe it’s to disassemble the motor easily to rinse it inside after each use.