80100 direct cooling


Very cool board Mat!
I tried the exagons grip like yours on a surfboard, they work just fine. While on your feet there’s almost no differences with good wax, while paddling and managing a low volume shortboard with your body, no wetsuit, the feeling ain’t the same but you’ll get used to it and you don’t need to paddle on your foilboard… or this is my wish!


Could someone please post a link to the source for these 80100 motors? I’m pretty sure they are Alien Drive motors but I my website fu is failing me.



this one: http://alienpowersystem.com/shop/brushless-motors/c80100-outrunner-brushless-motor-80kv-7000w/


test of the new setup:

  • the board is way more stable

  • the cooling system works well, ESC never went above 40 celsius

  • the grip hexagon are not bad, but a bit slippery at first… and i forgot - a few in critical areas.

  • the remote with cruise control is magic… way easier than with a regular trigger to manage.

  • on the less good side: my 200amps breaker keeps overheating and shuts everything down… so i opened the hatch on the water… re-armed, and good to go… the first time… second time, seems like the Coulomb meter shunt was also quite hot, and when i open the hatch, some water dripped on it… working fine for a bit, but after 5 minutes complete shut down… and paddle back.
    the connector on top of the shunt looks fried…

  • still not much data:
    according to the go pro GPS: i start flying at 10 km/h and cruise at around 20km/h. i was far from the max power… i couldn’t get there as the motor seemed to be loosing sync with too much throttle…
    after 30 minutes playing around, falling a lot, the last time i checked the meter it was saying: 60% remaining …


How do you find riding with a leash? Is it ever problematic?
Im thinking about using one when my build is on the water.


leash wasn’t a problem so far…
as it’s coiled and attached higher then the ankles, it doesn’t drag in the water…


what did you put as thickness of plywood, it’s not too heavy?


plywood is 5mm thick… the wood box itself is not very heavy… and not that strong either :slight_smile: the strength (and the weight) come mostly from the fiberglass around it, there are 2 to 5 layers of 6oz fiberglass all around on both sides of the wood.


thks Mat, I found in italy a producer.

Good Job, I saw your video!!


I m looking your ESC.

There are 2 wires red and 2 black.

I think, 1 black and 1 red to the batteries and others? I have no idea.

I saw a yellow cable for watercooling, Can I ask how it is work?


it’s a 400A esc… so the input wires are doubled to handle the current… but as i don’t plan to go much higher than 100A, i’m just using one of each.

for the water cooling, i’m using a small pump like that one: https://www.ebay.com/p/Priming-Diaphragm-Pump-Spray-Motor-12v-for-Water-Dispenser-N3/1451308434?iid=113116825549&chn=ps

It picks water from the bottom of the mast, run it through the ESC and send it out on the bottom of the board.
It’s self-priming, and can pull the water up more than 1m with no problem, runs on 12v. to start it i’m using a temperature sensor attached to the ESC, the pump start when the ESC reach 40 celsius. I’m not sure how long it will last, but it’s doing its job for now :slight_smile:


Hi Mat,
congratulations to your really nice setup. I love the idea to have cruise control. Do you can provide pictures and more details of your remote? Looks like you have the most future proof setup in my opinion. What is your consumption at various speeds?



all the info for the remote is here:

there are a few post in a row : the concept, then the details (cad and code) and finally a couple videos.

i’m not sure if it’s very efficient, but if for sure is very simple :slight_smile:
I don’t have much data yet… not even max current as each time something burn (amp meter, coulomb meter…) and my ESC doesn’t record.

once i tidy up the electronic bay i might be able to put my phone inside to record tracking and the amp meter next to it with a gopro mounted inside :slight_smile:


It’s going very well Mat, awesome job!

I had sync problems as well, you have to increase the timing, Ive found 18 degrees - 30 degrees to be the best for these motors. I’m currently using 24 degrees but maybe even try 30 degrees for this big motor.

Also having a propeller that is to big makes it lose sync more I’ve found, Why don’t you try 3D print one that is smaller so the motor can rev higher?


yes, that was my plan… i had to reset the ESC because it didn’t want to start… but that was a dumb mistake i made instead… the receiver was sending 0-180 instead of 90-180… and i forgot to reset the timing after :slight_smile:

for another prop, im not sure the motor has issue to rev… if the 20 km/hr from the gopro was accurate, knowing that the theorical max speed should be 32km/h and that i was not at more than 2/3 throttle, i think the motor doesn’t have too much troubles to rev… except for that timing issue… i’ll try it as soon as fix it.

only thing that bother me now is: why is the 200amps breaker heating up enough to trip when the ESC barely heats up at all??..


I wonder if increasing the PWM rate could affect this or adding capacitors? It may not be a perfectly smooth current draw from the ESC and this could have an affect on how the circuit breaker handles the current.


Maybe because your connection is bad. Had this issue as well. I changed the fuse holder to a better quality one then it worked for me (200A fuse).


Great idea about a gradual power down AND the dead man’s switch


Nice work, I also think you might have a bad connection on that breaker. I am pretty sure when I had a bad connection it was causing a motor de-sync issue also.
I use that same pump, I have now made at least 10 test runs and the pump is still working. I start the pump when the batteries get connected and it stays running always until I’m back on dry land.



Awesome design, thanks for sharing.

Two questions:

  1. Have you thought of designing the prop in such a way that it will be around the rotor, not behind it so the rotating surface will generate thrust instead of drag.

  2. I read here: https://forum.openrov.com/t/seawater-vs-brushless-motors/35 that a good solution to prevent corrosion in an underwater brushless motors is silicon spray (mold release) - have you thought of that ?