I was thinking about building it this way too, but then decided to take the “under board mounted” Foil Assist route due to safety concerns. I was thinking of solutions but came to the end that I prefer to have a board between me and a burning assist.
But I would love to give the body mounted assist a try one day as I can see the advantages it has → less swing weight and bigger battery
How do you manage the risks of a burning esc and potentially battery?
Hello Rémy!
Great to see you here. Amazing work. I will switch to 5085 too and probably improve my leash. One day I will even charge balanced… looking forward to meet you again.
Regards, Robert from Austria
The esc is in a sub-box in the main box, glued to an alu radiator that is water cooled outside the box, and it is supposed to stop operating if its temperature is above 90 degrees (blheli settings)
Several friends and I have been using and abusing this system for a year now, so far no overheating. A friend had his box flooded, the batteries (samsungs) got hot and it turned back, that’s it. The solid state batteries are supposedly even safer for fire/explosions, I think it is relatively safe, although I could be wrong.
Yes, batteries should not start to burn even when under water regardless the chemistry. From my research and calculation putting an xt90 of a 12s pack into salt water would cause a current flow of around 7A. It would just drain your battery and corrode the contacts. But I have not verified in real life yet, so I could be wrong. Your friends experience backs that up though. I was just measuring the resistance between the contacts of a drowned xt90 in salt and fresh water.
So from my point of view the single risk is the esc catching fire and in the worst case causing the batteries to burn down too.
Seperating the esc into a sub-box that probably holds back the fire from the batteries is a good idea
Hi Remi, awesome system you got! I see that you are riding closed to sagres. Planning to come with my foil soon, woluld be cool if we can meet and share a session
Trying to update my assist as well, especially on the connectors side. Can i ask if you got the LD28 docking version? Or one of the other versions?
Can i ask for the reference of the ali coiled (cant find it) and the length of your ozone wingfoil leash? Is it the one size wing leash ?
Hello, I am in Santander at the moment unfortunately. Usually in south portugal winter time. It’s the LD28 docking, longest version of the 3 options. For the cable, 3core 13AWG, stretch 2 meter (actual uncoiled length is about 3.5m), https://es.aliexpress.com/item/1005003176716502.html?spm=a2g0o.order_list.order_list_main.85.5d361802lU2K4D&gatewayAdapt=glo2esp
For the ozone wingfoil leash (one size I think), I cut it about 20% so that maximum stretched length is 2 meters, coiled cable is 2.5m, this way it takes all the force and protects the coiled cable.
Thanks for posting all the detail. 13awg at 3.5 is a long cable, do you notice it getting warm at all? Maybe the lower current draw of the 5085 motor helps with this.
I’ve noticed my 13awg shorter cable gets quite warm to the touch with 6374 Flipsky motor and twin blade genuine black FOil Drive prop blades.
Looks like you on to a great build .
Do you think the 5085 motor would have enough grunt to get a 95kg rider onto foil? I’m mostly using UHA 870 or 670 when waves are bigger. I like the idea of less drag on mast with smaller motor but don’t know if it would have enough power to get me up?
Hey Astan! Have you played around with a foil assist already? It depends on how many amps you need at 44v. If you have good technique to avoid flat water start, using waves to get on foil, and get the speed from the wave and pumping before efoiling, I suspect it’s possible at least on the 870.
A little on assists but more on my boogie. My assist I built was over powered with 160amp esc with 6384 motor on 12s but I’ve just finished the in board build with a vesc and yet to test. Only thing is after foiling behind boogie on prone board it’s hard to go to assist again I’m after the more natural feel assist. I have ordered motor and vesc and will give it a try cheers for advice I think your right with good technique it might still work
looking forward to meet you again.
Looking forward to see you again! 
