I'm Going Under (water)

Snarls

Gravity Tester
Mentor
So this project turned into a bit of a fail, and I had to step away from it for some time. I though I would just share what happened to give some closure for those following this project. Back in June, it was a rush to get the body painted and electronics installed before setting out on my beach vacation, so unfortunately I did not document that. I do have some pictures of the finished product during some of my testing.

I ended up fighting a battle against leaks. Mainly, the larger rear hatch was not watertight beyond splashing water over it. First I tried different gasket designs; first with silicone, then rubber, then some backer rod. Some of those worked, but only until the ROV was submerged deeper or tilted beyond horizontal. I noticed that the way I was securing the hatch, with one bolt in each of the four corners, was leaving room for the hatch to bend at the center of each edge. This was allowing water in no matter how tight I bolted down the hatch. To try and combat this, I made a new hatch out of plexiglass and wood that I had available. This hatch resists bending more than the 3D printed one, and provided the best seal yet.

I still had to deal with small leaks at the motor mounts and tether mount, so I decided to get some silicone conformal coat and coat all the electronics. I also decided to do this because of another issue I was facing; the thing was way to light! Yes, that sounds a bit strange coming from a hobby where more weight is a problem. I did the math and determined I needed the ROV to weight around 7 lbs to be neutrally buoyant. All up, my ROV was just under two pounds, meaning I need to add 5 lbs of ballast! So instead of fighting leaks and having to add 5 lbs of what I was thinking would be sand, I decided to flood the entire ROV and make the electronics waterproof.

I spent a couple days getting the electronics coated and went to the pool for some more tests. Finally the ROV was alive and working in the water! Well only for about 30 seconds. Then the ESCs started acting strange and restarting. Control was intermittent and overall not useable. My fpv feed was also not working, and my monitor was slowly growing a spot of dead pixels that was making it unusable anyway. I was however, able to control the ROV long enough to tell that the thrusters were strong enough to move the craft. I had some concerns about them so this at least told me that.

By this time it was nearing the end of my stay at the beach, so I decided to put the project on the back burner. Don't worry I did not spend my whole vacation debugging this project, it was just one thing to do. Now a month has passed and I am ready to get back on the horse for version 2! The good news is I tested all the electronics recently, and everything (except fpv feed I haven't checked) is ok and working. So v2 will be less about the electronics and programming, and more about the physical ROV design.

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