plywood is 5mm thick… the wood box itself is not very heavy… and not that strong either 
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: Priming+Diaphragm+Pump+Spray+Motor+12v+for+Water+Dispenser+N3 for sale online | eBay
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 
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?
Cheers
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
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
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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
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.
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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).
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Great idea about a gradual power down AND the dead man’s switch
Mat,
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.
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Mat
Awesome design, thanks for sharing.
Two questions:
-
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.
-
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 ?
Thanks
Hovav.
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Before buying the propeller, i tried designing one, but i postponed it :
- This is a very big motor (80 mm diameter)
- The drag will significantly increase with every mm i add to the diameter.
- To get the blades strong enough, i’d need to increase significantly the diameter.
- and that solas prop seemed quite adapted to the power and RPM … and i might have gotten a bit lazy
- as i wasn’t sure of the rest of the system, i stuck to a known working solution.
But for sure once everything is stable and i get some time, the prop will be revisited.
Even just a smoother reduction of diameter between the motor and the prop hub would help, but first i need logging capability …
Regarding corrosion, CorrosionX HD is magic, i barely rinse the motor with clean water after getting out of the salty bay where i test, and no corrosion issues so far 
2 Likes
From what I understand, the propeller will dictate a lot about the system, such as the efficiency, current draw, and total power output. You might want to make it a larger priority.
that’s why i need to be able to log current and voltage first
i’m using the spray…
But first the windings are covered with a few coats of Epoxy, i trust it more to protect them in case something hard enter the motor, and it’s not too thick, so i don’t think it affects cooling too much.
CorrosionX is more to protect the bearings and the exposed metal part…
2 Likes
Did you paint on the epoxy or did you dip the core? Thanks for answering these questions, this is the next step in my build once I get the remote wrapped up.
Can you tell me what the dimensions of the bearings are (ID, OD)? I would like to look for ceramic bearings while I wait for my motor. Thanks!