I’m finding that after I’ve watched lots of YouTube expert how-to vids I still can’t do it as “simply” as they show😉
Whatever works is my motto!! I’m going to experiment with your approach to see if it works for me as well.
I’m already craving longer run time - battery capacity, that will drive a new build so I think it’s cool that you are trying something a little out of the ordinary. Well done!
Logs with X-Over XL front wing + X-Over 46cm stab. The beginning has a section where my brother was learning, so that part is a bit messy. When exploring the lake I got about 15-17A current consumption, which is my record so far. ESC temps stabilized to about 50-52 celsius.
It’s a very nice an easy wing setup. Perfect for learning and laid back exploration.
Sounds like this is a good foil for you.
I am a bit curious about your battery level data.
Not sure which is outbound and return track but when I tap them that level indicates 82% on both even though you have traveled quite a distance between those points??
To be honest I didn’t even know about that data channel. Never tried it before. It’s definitely incorrect… I’ll see if I can tweak the Metr settings to improve it.
The battery voltage is valid. You can use it to estimate battery level. Consumed Wh also gives you a good idea of battery use.
Longer log, warmer weather. We took turns with my brother in the beginning of the session. He is learning fast, already foiling well when kneeling, and stood up a few times as well. ESC stabilized to 60c, battery under 30c after the ride. 67 minutes ride duration. It’s possible to foil at 15A, as demonstrated during the very last minutes of the log. X-Over XL + X-Over 46cm stab.
I think up to 1.5h ride time is doable with this battery and foil set if you don’t fool around/do a bunch of takeoffs and just maintain a nice cruising speed (~18km/h maybe). From totally full to totally empty. 1h 45min is probably impossible.
Battery after the ride. Nice and cool (10c over ambient):
I recopy you answer from the other thread here to clarity:
"jkoljo
I think I’d prefer to discuss build details in my actual build thread, but here goes… 
I am using Metr Pro CAN + separately bought MRo M9N GPS for logging. Unfortunately Metr is currently discontinued, and the original creators are working on a new project. Meanwhile I would look into the used market or the new Vesc Express logger. It seems to be a capable unit, but I also think that the software is not as finished as Metr.
I am using the 30A BMS, not 60A. I am not using my VESC through the BMS so discharge ratings don’t matter. Only the charge rating matters, and it is 20A for the 30A (discharge) model of LLT BMS.
You should not connect packs with different parallel cell counts in series. Unless the actual battery capacities are an exact match, you’ll end up discharging the lesser battery more, which may not trigger a low voltage cutoff early enough. This may cause the lesser battery to discharge too deeply, which damages the cells and makes charging dangerous as well.
Also, water-cooling for the VESC is probably not necessary. And it’s definitely not necessary for the battery. For me it’s enough to have the VESC in an aluminum box. It doesn’t even conduct the heat anywhere, but still stays cool enough."
HERE MY ANSWER to YOUR COMMENTS on Battery calculator for eFoil - #28 by macfly1202
1/ about Metr : I am trying to find one and have a look to Vesc Express logger
2/ super clear about BMS: you use it to charge and balance only not during riding - make senses why 30A only
3/ About my idea of 2 pack I know it must be the same in serial. I was saying I need to find which battery is more suitable from 6S10P to 6S14P but it will the same (6s10p+6s10p, 6s12p+6s12p or 6s14p+6s14p) ! safety first !
4/ about watercooling: I prefer to be more safe first and, for sure, a pump a another point of potential failure. Only data will speak > so I need to see the raw amp at high frequency to see what happen.
In my step 2 build, when I will made the board, probably I will use a passive system with CNC alu box.
Because I know very well Ardupilot, I will probably use it as a logger if a can’t find a Vespress logger or Metr. I have all spare for Ardupilot on shelve.
Kind regards, Jean
Great! Using Ardupilot for logging makes sense as you know your way around that system. You can configure VESC stream data in the configuration app.
Regarding watercooling, you can check out my MakerX Hi200 temperature in the logs in previous posts. It’s housed in an aluminum box. No watercooling or conduction to mast etc. So maybe try without it and add it later if it’s really necessary.
I suppose my 75350 is completely overkill but I had some failure on RC plane due to low/limit capacity. For my safety, bigger ESC means bigger mofset means low temp when far to the high hard AMP limit. Probably I will loose some efficiency with this mofset not fully used but logger will give all I want to know/analyse. I’m working as a sofware engineer in Machine Learning area so it’s always a pleasure to digg in datas 
I agree with you that watercooling won’t be necessary, given the aluminum surface. To be seen. I also chose this ESC model because it is able to output more logs according to Flipsky’s specs. I think the material design is also more recent than the problems encountered on 75200s.
Does anyone know of an 18650/21700 li-ion battery organization simulator? (example 12s10p in square , rectangle , many row …)
I don’t think you’ll lose much efficiency with that controller. You could even gain some. The mosfets in your controller have a lower resistance, so there is less heat generated. On the other hand, they use more power to switch, and your current measurement has less measurement points in the eFoil current use range when compared to Hi200 for example. This may cause some noise in the motor output (losses). Ultimately I think that the lower resistance dominates and you will end up at the winning side in efficiency. Let us know when you get some tests done.
I’ll keep you posted. I’m starting to receive the elements I need to start building. Thanks 
New efficiency record, 47.9Wh/km over the entire session, so including a few takeoffs and some higher speed running in the end as well. Stable foiling at about 16A @ 14S, battery was at about 51V. So power consumption is about 800W. This was with Curve MT + Surf 40cm stab.
To get this improvement, I got my Gong V2 motor mount rear clamp MJF printed and removed the motor tail support. I made a tail cone without the support fin to retain the smooth motor to prop transition. I’ll release the new files soon in my motor mount thread. I added a cutout in the motor mount to reduce material where it’s not needed. This made the part a bit cheaper. The rear clamp part was 48 USD + tax and shipping from JLCPCB.
Congrats. Fun to improve your personal bests.
As I make alterations to my setup and my riding is improving I’m finding that I can travel further and my max session time is also increasing.
Do you credit the improvement to the reduced drag of removing the tail support or smoother more consistent riding?
I am pretty sure it’s the reduced drag that gave me the biggest benefit, since this was a drastic, about 15% efficiency boost with the Curve MT. Riding technique improvements have been more gradual.
I’ll test Veloce MT + Fast 40cm stab efficiency soon. First I need to learn to ride it properly, though. It’s significantly more demanding than the Curve MT setup.
Hi, try the Veloce with the surf stab first. It’s actually the stab that makes the biggest difference. I would assume that you will also gain some efficiency with the Veloce stab over the surf stab.
However, you will find that you will need more speed with the Veloce - it’s only comfortable from 25kmh up.
What is your all up weight? I have similar setups (Flipsky 65161 120kV; 14s with Curve MT+LT, Fluid LT, Veloce LT and both Surf and Veloce M stabs) and I am getting ~55Wh/km @25km/h average. FR and Hyperdrive Props. 130kg all up.
I would appreciate it if you could explain the logic behind the weight variable.
To my thinking weight is an issue during the “take off” part but once your foiling level and at a consistent speed does it make a difference to efficiency level?
In other words let’s say two people weigh 70kg and 90 kg and both riders have exactly the same riding skill and they take turns riding the same rig in the same weather conditions.
There is logically less power used to get the lighter person up and flying but from then on would the extra 20kg make a difference?
Don’t mean to hyjack your thread. Sorry.
My engineer brain thinks that given the same speed and foil setup, an eFoil will have some base current consumption to overcome drag and such losses + some current consumption that depends on rider weight in a nonlinear way. 20kg more will surely increase consumption, but not by +33% if you compare a 60kg rider to a 80kg rider.
I weigh about 67kg, my battery weighs about 8kg and the rest of my board I haven’t measured but it’s surely less than 20kg.
Thanks for the suggestion to try the Veloce MT with the Surf 40cm stab. I’ll follow the advice. The Veloce MT + Fast stab combo felt very nervous when foiling on my knees, but I probably also had pretty low speed. I am comfortable up to 30 km/h with the Curve MT but the efficiency greatly suffers. At about 30km/h it’s 55-60Wh/km, whereas at about 19 km/h it’s 40-42 Wh/km.
I don’t mind these discussions at all. Actually I greatly enjoy them, these are really a chance to understand eFoiling much better 
@Foilguy: The lift that needs to be created for each rider costs power
in a theoretic example a 80kg rider at 20kph needs 1000w to overcome gravity and drag, and a 100kg rider at the same speed and same wing angle would not fly - so wing needs to be tilted more to get higher lift. This increases the drag in the water so he needs 1200W (or something) to fly at the same speed.
@jkoljo: i have just gotten a veloce mt since they were on sale i find it somewhat less stable than my curve LT but not really a game changer for me - it’s a lot faster than the LT wing though (which seems to somehow bottom out at higher speed for me)
I like it but the falls are starting to hurt due to the higher speed!
Not being an engineer I don’t really have much of a base to comment on this, but I have a life long passion to learn.
That said it’s my perception that once the rider is up foiling in a level consistent attitude the pitch angle of the foil is also consistent. It is neither climbing or descending. Therefore the weight that is above the foil shouldn’t have much effect. If the pitch angle changes then the weight becomes a factor again.
I understand that the energy required to transition more or less weight to the level “neutral” position would vary. That part seems very logical to me.
It’s like i explained. Maybe easier to understand like this:
The lifting force is created by the flow around the wing: same speed and angle of wing gives the same lifting force.
If you load the wing more, then more lifting force is also needed - otherwise forces are not in balance and we will start to fall downwards
How to get more lift?
Either increase the speed or increase the angle of the wing. A force balance will be found with the higher lift, higher weight on wing so you won’t be going up or down.
A drag/lift curve of eppler 817 profile:
(which is a wing profile i think was used on older hydrofoils)
Cd is drag coefficient / Cl is lift coefficient
Alpha is angle of wing towards flow
You can see on the Cl vs Alpha plot that it starts to create positive lift already at negative wing angles and the lift peaks at roughly 7.5 degrees upwards angle. At higher angles than that the wing stalls.
Thank you that is very helpful. The charts help me get things that I struggle with in just txt.
Thanks for you patience. It was never your explanation but my ability to comprehend what you were expressing before.
Im thinking I should go on a fasting diet and lose some of the extra tonnage I’m dragging around😀
