I’ve been looking at molicel p42A cells in 21700 format. About 30A 4Ah for each cell so a 14 cell pack at 60A isn’t too bad
I think there are a couple of ways to accomplish a paddle assist…
Wavejet style pod in board
- nothing needs to be attached to the foil so no real faff
- slightly slower, but shouldn’t matter as its designed to be an assist
- will need have the board on the water for the assist (ultimately its a jet-board with a foil)
Motor pod just under board
- can be attached to motor or board
- can be a jet or prop
- will be slightly faster than “wavejet” pod
- batteries and ESC could be in board or motor unit
Motor at half mast
- needs to be on foil
- batteries in pod
- Folding prop
- prop further away from you
- don’t need to get board on water for a boost
The 2 battery options I’d consider are either Lithium Werks ANR26650M1-B or the Molicel P42.
@SoEFoil interesting, it’s a shame the lower voltage and capacity of these, else you could build a small module with insane power! or maybe you still can it just would be bigger 
The 21700 P42 cell looks interesting! thanks for the tips @Alexandre and @Larsb!
wow! the ANR26650M1-B cell is rated for 200W in 10-second bursts.
Considering updating the OD spec! currently, I have an OD of 60mm, but going to an OD of 70mm allows to implement the 21700 cells and more space for electronics, wires, and cooling areas. also, newer used the 21700 formats before! the only penalty is size and weight, but probably worth it overall.
18650 → 110wh
21700 → 177wh- 106wh
Motor update:
Ordered these motors to test. Still, I do not like the idea of running outrunners wet, but they can also be easily replaced
Outrunner 6355
Outrunner 5080
@Jezza its nr 2 and 3 i am aiming for!, want to avoid having electronics in the board at all cost!. this way you can strap it to your foil or your longboard fin mount. i just need to figure out a way to send a signal 10-20 cm though water without getting the local navy subs annoyed 
,
wonder what frequency and power is needed, or maybe you could use an audio signal combined with a radio signal!, kind of like a whale with a telephone, so he can speak with both his whale friends in the sea and the local aquarium(by phone)?
Look for the suunto scuba diving communication between wrist computer and oxygen bottle, it is specified in their certification sheets. If I recall correctly it was around 100kHz…just shortly above audible, at least in comparison with >300MHz of all other “ordinary” RF coms.
Also the fish finders like the Deeper Pro use similar frequencies.
But the lower the frequency the lower the data rate, also multiple devices out max the band pretty fast.
Also for ESC, heaving only those short bursts and relatively low powers I would go for some small VESC, like the maker X, A50s, or even the Mini4.
Still I guess with that high KV outrunners you must go to 6s2p and some rather small diameter.
Can you point out whats wrong with the scuba jet?
The second version already got up to 1000W, 200-400Wh battery options, wireless controller, water tightness designed for divers etc. All at 3kg and designing a mount should be easier than getting rechargeable batterys watertight down there…
Maybe @Frage could chime in as he has a first working torpedo unit since summer 2018 with a 41Mhz remote and maybe a V2 since last summer (2020)…
If going for 6s , you give can shot for esc hoobywing 180a 6s ,nice size , heatseak can be shaped into a curve , but no current control , but proven to be pretty strong
Hi guys,
If the idea is to create one prototype I think a modification of a 41Mhz remote control is the perfect approach.
If you want something more professional a LORA Module in 433Mhz works fine. I did some tests this summer.
Check here : WeTransfer - Send Large Files & Share Photos Online - Up to 2GB Free - It s a test with a servomotor controlled by 2 lora module + arduino. The emitter sends a signal at 50hZ, The receiver is at 1.5M in salted water - a simple 3 wire cable connecter to the servo motor show that the control is smooth in realtime. If you want to work on a waterproof remote control with LORA module… I am interested to exchange about this point. We can also imagine to work with 170MhZ modules
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interesting with the scuba diving computer and fish finder. Did not think about these products!
to your point with a foil module low data rate should not be an issue. As you only need a single button or maybe 2 button remote.
dang! I just bought two of the VESC 4.2, but the Mini 4 or a50s looks better!
I think the scuba jet is awesome! but I do not like the diameter being 80mm. this makes it harder to mount on a surfboard and the mast of a foil… but still doable. This is also why I am reluctant to use 21700 cells as you need to increase the OD. I also want to investigate folding props and improving these types of products for foiling and longboarding. Here I believe size is very important for functionality.
Hi!
Your beluga pod is awesome! are you still working on it? maybe a v2? :).
Not having a heavy board should give you a great ride experience! how is it to ride compared to a design with all batteries on the board?
I do not like the forme factor of modifying an RC remote, implementing a Lora sounds nicer. Is power consumption an issue with these modules.
Also happy to collaborate on a remote solution. I have no idea what frequencies to use, but 170Mhz sounds good 
Actually having the weight in the board is the best place to have it. Think of a sledge hammer. If you hold it by the handle, then the head and weight is far away from you. Your movements are slower and you have less control. If you then hold it by the head of the hammer, all of a sudden it becomes super easy to move length of the handle around and you can move it much faster.
With foiling you want the COG distributed between your feet for maximum control.
If comparing to a hammer the board is more like the head of the hammer than the foil is. A lighter board should increase manluverabilty as the board tends to move around the foil, the foil is more the axis of movement for the board?
@Hiorth for the battery, have you considered using a high discharge LIPO? That would enable really good power output for a small diameter/overall size.
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When you foil, your COG is based around your board and feet. The easiest way to test this:
- take your efoil and strap 5kg of lead to the foil fuselage or mast. Ride it and see how it feels.
- Then take that same 5kg and place it between your feet on the board.
I can guarantee that it will feel much better when the weight is on the board.
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Good point, but still I would argue having a light board increases maneuverability as the board can move faster without having the extra mass to accelerate, especially when doing turns and such. Also, you should get some bouncy from having the motor system and battery underwater ( not in my case as it is halfway up the mast but definitively in the @Frage system.)
Also experienced the ride experience is more fun when running 2x 6s 16000mah batteries, compared to running 4x 6s 16000mah batteries. not tried adding mass to the foil, but would be interesting.
Considered lipos, but not able to pack them in a nice manner in a tube 
if you know of a cylinder-shaped li-po that would be awesome!
Concept layed out.
test printed battery. 12s 18650 fitts inside a 60mm OD tube. alternatively 12s 21700 fits inside a 70mm tube.
the big question. Is it worth all the struggle of making the system 60mm OD? or should I go 70mm OD??
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7s2p should also fit, rather would go that way…
Also hobby esc will fry your batteries, since they are the weakest link and you got no current limiter.
also you should take a look at the SK3 63xx motors, they are actually 60mm OD and so can sit flush after the 60mm tube. For these low powers even the SK3 6354 should be enough.
Which height do you plan to mount the system?
good point, but want to have the battery-esc connection in the nose cone to avoid having to build unsccesary complex battery and not needing to manage a long length of wire.
also will use a VESC based ESC with current limiting.
Hi, Yes we are going to work for a V2 - I hope to try it in spring / summer 2021.
The feeling is completely different already on the first version… more like a snowboard without the feeling to have big weights on your feet 
- I have the same feeling as a classic “foil + kite or wing…”
The main issue with LORA is the bandwidth occupancy which must be under 1% - but this issue is not clear for me because it is possible to use some module like this : Communication for realtime transmission. I think the main issue is also the maximum power that we can use on this module for a streaming mode… Keep in touch
I doubt there would be a much difference between 60 and 70nm diameter in terms of drag. The good thing is, if you go with 70mm the 63mm motor will not stick out at all. And yeah 18650s are much better use of space!
@Jezza wouldn’t it be more about the neutral point than the CG, the rider will always be standing a little forward of the CG? When you look at videos of people pumping foils notice how much more the board moves compared to the foil. Could be different when turning though…
Hi. May be with the remote I build it can work with 443mhz. What do you think about?
Isn’t lower frequency better? Search for rc sub radio. There are plenty of bands available below 100mHz.
Extended antenna is also an option but you lose a bit of simplicity