Lake Merritt Monsters

Latest update January 27, 2019 Started on July 30, 2016

Ever since I walked over a pedestrian bridge on Oakland's Lake Merritt and saw 3ft striped bass hanging out in the flood tides, I've been fascinated what might be beneath the surface of the lake. Oakland has a goofy legendary monster called the "oak-ness" but I like to think of them as reflections of all the monsters that do live in the late. The striped bass, large bat rays, pacific pipe fish (brought up in the mouths of earred grebe's), and sea hares. Not to mention all the diving ducks, grebe's and cormorants -- all of these are monsters in the eyes of other creatures. I want to spend some time exploring this underwater landscape, and documenting more about the creatures below the surface. I know there is plenty not well about the lake -- with a tremendous amount of trash finding it's way into it, but even that will be interesting to document.

July 30, 2016
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In The Field

Mainly posting here now

The ROV continues to have some issues with connectivity that don't seem consistent. It dropped the line a couple of times in the water, and took me a little longer than usual to get up and running.

The navigational aid of depth and compass has not proved as useful as I hoped. Must disappointing is that the depth hold doesn't seem to work, at least not in the shallow environment of Lake Merritt.

One thing nice about the 2.8 compared to the Trident was that it's slowness works seems to work in its favor in terms of poking around. But perhaps that is just practice (also the control set up for the Trident was decidedly odd with left right connected to up down instead of forward and back).

I was excited to get my ROV out today, and headed towards Laney College, where the channel goes through the flood control. The South East bank near the playing fields offers a nice little slope down to the water. And it's a perfect little place to drop in. The tide runs on the other side of the channel, so there's an eddy on the far side. This is where I often see bat rays, anchovies, the very occasional halibut, and hints of other fish.

And I arrived at the perfect moment two because all over the channel there was signs of large fish hunting, breaching the water surface, anchovies leaping out of the water to get away and the larger fish splashing after them.

Alas, I was undone. Too excited I was and not paying attention to my wires, and I ended up twisting a break. I'd left my slip ring loose to observe how it worked, but had forgot about the observation part. Argh. I manage to patch it back together with tape, but it was too patchy and I gave up after the connection broke a third time.

I'd hoped I might have got lucky with recording, either a fish coming to check me out, or having got close enough -- but the water has been low visibility of late, and I got nothing underwater. I did manage to record some of the hunting from above at least.


After my last successful run with Lake Merritt Observatory, I decided to install the compass module (I somehow missed this in the initial build), and also install a slip ring in my reel. I was getting tired of uncurling the kinks in the wires to my topside box (occasionally resulting in loss of connection). I ended up finding this excellent post. I bought a slipring from Adafruit.

I went a little more low tech on the rest. I found that the top of an old Marmite jar fit perfectly into the opening into the center of the reel. After cutting out a hole for the slipring, I glued it in and proceeded to all the wires and did all the soldering and seemed to be back in business.

I made a bone-headed error though, which I only found out after I ran the ROV out again. Out in the middle of the lake, the ROV just died. I hand reeled it back in. Back at the lab -- I found that the wires had twisted and broken. The slip ring hadn't worked at all, because I installed it backwards. The slip part needs to be on the inside! Slap forehead.

Today, with a new soldering cleaner I'd gotten recently at Frys, I quickly solder things back in place. AND even replaced my one lousy engine. I fear that the engines will still be mismatched, but hopefully they'll be a little more equal than what I have now.

I also dismembered an old engine to see if I could figure out why it was slowing down. It was not obvious, but it did make me understand how the engine is constructed and where the best place to lubricate is... from the very back of the engine where it's held in place.

image-1 image-1

A second successful run with some guest drivers. I came down to the Lake Merritt Sailboat House again with Katie Noonan's Lake Merritt Observatory project and got in the water again.
This time I had a new screen capture system ready, and off we went. I had some guest student drivers 6 to 17. We decided for next time we could do with some sort of umbrella -- it was very difficult to see what was on the screen in the bright sun. There was some funny things going on with the camera. It seemed to freeze at various points in a way that has not happened before whenever I took a picture or tried to move the camera. I rebooted in the water several times to get it back, but that was the only hiccup. I've also decided that I will install the depth control compass so that I don't necessarily need to see the ROV to know where it goes. Or at least give me a better clue. It made getting under the docks a little fraught. The stars of the video are mussels at work, but there are also anemones, a crab on the dock piling, and various little fishes darting about. And some etherial looking lights as we drove under the docks.

A successful run! As part of a Lake Merritt Observatory run, I thought at long last to get my rover out... Things were not in perfect order. After my last run, one of my engines is not super happy, and one of the tubes has a bit of rust on the metal. I'd done a bunch to try and troubleshoot, and things still seemed to run. I think I still have an extra engine after first time I switched an engine out, but it seemed more trouble than it was worth.

Once I got it in the water, things went swimmingly for the most part. The power difference in the engines did make steering a little difficult, but not bad enough to get me in trouble.

Exploring a dock sides, the coolest stuff I saw were big clusters of little anemones. A Black-crowned Night Heron stalked the rover for a little while, but I dissuaded it with use of my x/y engine.

That is still something I need to experiment with. Diving for any length of time with ability to explore was not easy. I have to have another go at putting on some ballast.

A few big pluses to the expedition:

  • My computer (with a new battery) lasted a good long while.
  • My wire setup with cable crank worked great (the one small caveat being the connection to the top fell out once as that wire still twists).
  • Three great conversations about the rover and the lake with 3 fireman, and two women.

The biggest disappointment though was that my screen capture option completely failed upon me. I've had to find a new solution for that. Good news is that I will be out again soon!


Finally got out into the wild again. And ... learned some more lessons!

  • The first thing that went awry was on the top side communication box. Putting the wires the little box that has the springs to hold the wires in fell apart. After a moment of despair, I settled in to getting back into working order, and succeeded. Though, I'll have to work out some way to keep it in place... One could easily drop a piece in the wrong place.
  • *My tether management system. * Turns out I hadn't quite thought it all the way through, and I'd not actually tested it. I ended up laying out a length and just seeing how far I got. Once I got it home, I did a little reworking of my winder and I think have it in a good place again.
  • *Control direction. * My controller is working in the exact opposite way that feels natural so it was difficult to feel I was getting anywhere. I later realized I could have just turned it upside down and been happy, but I ought to figure out how to adjust the code for that. Testing it is a bit of a pain though, so almost might as well just leave it as is.
  • Tether+rocks=bad Luckily due to my earlier constraints I did not get very far, but rocks, even small ones were proving problematic. My next test, I'll have to pick an area a little more devoid of rocks. But having better control will at least allow me to go back. Also having someone doing a little bit more tether management with me would be useful.
  • * Scummy water * makes for crummy visibility! Be careful where one drops the rover in, I guess! (another negative for Lake Merritt perhaps given concentrated run off)
  • *Vertical Engine trouble * The biggest downside to my run -- my vertical engine was working fine for about 10 minutes then decided to stop working. Can't quite tell what went on here, it was working fine when I got it home again after cleaning, so maybe it was just jammed by a little piece of debris.

More soon.

In hindsight, I realize the vertical engine trouble was trying out the experimental feature to maintain depth. All it seemed to do was disable the vertical engine. I discovered this in my latest expedition.

Back at the lab, been doing work troubleshooting my engines... One of my engines wasn't working right. Support suggested I update all the software and firmware and all that goodness in case there was something buggy. For good measure, I ordered some new engines along with SD card with the latest and greatest.

The update process was less fraught than I expected, and I had the ROV back up and running pretty quickly. But alas it was to no avail, so I began the slightly tricker task of replacing the motor.

In stripping wires, I managed to to rip one wire off of one engine -- luckily the order comes with a couple to spare. I much more carefully stripped the wires down and set up to solder the engine on.

The starboard engine has the shortest wires, so the least slack to work with. Which was problematic because with my now rusty soldering skills, I managed to blow it on one connection (soldering quickly on those wires is important, because it's easy to overheat the wires and melt the plastic sheathing -- or, as it turned out in my case, one end of the plastic shrink tube that was to protect the connection).

But it's on and back in place. And to my relief, the engine sounds more or less the same as the other -- so hopefully I'll be running in straight lines from here on out.

I still can't tell why the original motor was bad. It doesn't appear to have any defects or anything stuck inside, so who knows.

Now, I just need the rain to clear up a bit -- and I'll be out on the lake.

This has been fun to read! I hope you get a chance to re-visit the mysteries of the Lake Merritt abyss

Well my first run at the lake did not go all that well. The run was short and not straight for a variety of reasons, and I've not yet returned to the water. The most interesting thing natural history wise that happened was having a juvenile western gull become interested in the ROV.

First problem -- learning that i should have figure out the umbilical before I went out to the water. The process of unwinding the cable took nearly a full hour of painful work and nearly drove my help (a kind and gracious friend) mad. I thought it was going to be a simple task. It was not. Subsequently, I found a device for wrapping up cords that I think will serve me well in the future.

Second problem -- the rover wouldn't go straight. I've not been able to diagnose this problem as of yet, but hope to spend a bit more time on it this week.

Third problem -- the rover wouldn't dive. I think this was simply a matter of weight. It is salty water, so I need to add some more ballast. Which I hope will be easy.

Fourth problem -- it nearly burst open, the electronics chamber. Subsequently I learned that the electronics heat up the air in the chamber and expand it, putting more pressure on sides. Luckily it didn't popup outright and leaked very minimally. The two solutions seem to be either -- putting a weight on it for some hours before putting it in the water, or getting a vacuum pump and reducing the air and creating negative pressure into the chamber. The latter sounds safer, but not having one handy, I'll probably do the former.

The fifth problem was safety. I subsequently had a very negative hostile (entirely unexplained) encounter with a homeless individual which has made me wary of the area, but will likely do it anyway, just making sure to have someone with me.

The interesting thing with the channel now is that it has had another culvert removed at the 10th street bridge which will bring new changes to the lake as a whole affecting the tides. The channel was closed off for 5 days with two inflatable dams while the crews worked day and night (or so it seemed) to remove the concrete and reshape the channel.

Thanks for sharing the challenges Adrian, and glad to hear you're still at it. Keep going!

Success! My ROV is complete and AC Grebe (R 001) in the water. Things appeared to be A OK, no leaks that I could see. Motors all functional.

I did notice it seemed to turn one direction better than the other. And I'm guessing i might need a little more weight.

I also note that it would be much more intuitive to have a game controller. But I've not been able to successfully get a controller working as of yet.

By hook or by crook I am aiming at the weekend of September the 18th for an actual in the water expedition. I have several offers of help, just need to scout a good spot and find the right time (aka tide).

Hopefully in the meantime, I can figure out my controller issues.

The OpenROV bathroom tub test! Classic. I think there's a whole Youtube genre about this.

Congrats on finishing the build! As a fellow Oaklander I am always excited to see expeditions happening in Lake Merritt. Looking forward to following along!

Thanks David and Margaret. I also figured out my playstation controller problem as well. One step closer :)


Still haven't quite made it to launch just yet. I fell sick for a little while and have been struggling to find time since I've been better. And I've got one little supply I need to get before I dunk it in water -- lube for the O-Rings.

One sideline joy of this project has been working in my barn. A barn built for horses in 1908sh by an Irish butcher who ran a shop in downtown Oakland, and carried his meat around in horse wagons.

The barn is now split between two condo units, so we each have half. I usually work with the doors open, and have enjoyed the birds who come by. A California Towhee with a fledgling, some Dark-Eyed Juncos, and an Anna's Hummingbird. The hummingbird comes to feast on one of a backyard beast of a plant I have, that puts out massive cone like sets of flowers.

I was able to stand by the door and watch and get some excellent slo mo video of the hummingbird as it went about its business -- including checking me out.

I had a teacher from Oakland HS stop by. She had a bunch of Environmental Science students that wanted to follow along with your expedition.

Hey David, I think we've already been in touch... they have an old expedition ohsesa?

Success! Last night I plugged in two my computer -- and after an agonizing minute or so, the ROV blooped, and lights started shimmering on my board. It was a relief that I had not crossed any wires or the like.

It took me another minute or two to get the network properly established, and the control panel in place, and voila, there was my workshop on screen.

An hour later, I was showing it to my colleagues at Nerds For Nature at our monthly meetup night and was showing off the console and the rover. Lots of good discussion had.

I hope to finish up this week, and maybe, just maybe get it in the water on Saturday for some sea trials.

I've also been wondering, what I should christen this little vessel of electronics -- and I think I have landed on something around my favorite diving bird, the Earred Grebe: Grebee? Earov Grebe? Grebver? Grober?

I'll work it out eventually, but if you have any ideas...


Finally closing in on the completion of my ROV. I made one acyrlic gluing mistake (i had to reorder the electronics chassis), and didn't order epoxy - and wasted a good couple weeks looking in stores before i gave up.

Otherwise, the process has been quite enjoyable - and we'll soon find out how good of a job I might have done with everything else. My soldering seems better than my acyrlic gluing.

I'm lucky to have a good workspace - a barn built in 1908 for an Irish butcher's horseswho lived in Oakland.

Looking forward to having it in the water soon.

Expedition Background

Lake Merritt is not actually a lake. It is a tidal channel, where bay and east bay creeks mix, a brackish body of water. It was made a lake in 1869 when the mayor created a dam -- and over the years westerners move in and developed around it, the channel hemmed in by streets and buildings, paving over mud flats, and removing the willows and oaks that once surrounded it.

In 2013, 140 years after the original dam was built, the lake has been reborn, with the channel reopened to the tides and plans to open it even further removing obstacles further down the channel.

Those obstacles don't stop the tide and water though, and the bay slipped back into the water bringing more fish, and bat rays, and sea hares. Some months of the year you might see a flotilla of cormorants out hunting with brown pelican air support. An otter even swam about the lake one day (apparently only to move further upstream).

There are a few places you can see what is going on under the water -- cormorants, grebes, scaups, and other ducks diving, bat rays, striped bass, bait fish. Gulls commonly bring up mussels to eat, grebes can be seen snacking on pipe fish.

I would like to see what else might be going on there, or getting a different look at what can be seen from the surface. This might also turn up another ugly side of a lake surrounded and downstream from a city -- all the trash that we unleash, but hopefully that too can inform how we carry forward with the lake.


Hi Adrian, Any news? How's the build coming?

Just managed to get my toolkit together and am off on a trip today :/ so nowhere yet.

Hoping to get it built in time for the 2nd lake merrit bioblitz at the end of the month.

Hi, Adrian. Nice job. Some students from Oakland High and I have been building OpenRov's and would love to talk to you. We would especially like to meet up with you if you do any more explorations in the lake. My email is Thanks! We have an old expedition up at ohsesa in OpenExplorer.

Thanks ohsesa, I'll email ya!

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