Division II Builds Underwater Robots to Study Marine Ecosystems

By 8th Grader Ally

Early on in this final trimester, Division 2 started its longest project of the year: Sea Perch. I was really excited for this project, and in fact I'd been looking forward to it since the start of our Marine Science studies this year. After studying marine ecosystems and sustainability, we were ready for this project that would span from March to June.

To complete the project, each student pair creates a question based on what we learned about marine ecosystems, and then we try to answer it with the Sea Perch, a small water robot made of PVC pipe and three motors. For example, some of us used the Sea Perch to get to certain underwater spots for samples, and others attached a waterproof camera to see what was beneath. The project connected back into the marine sciences we had been studying all year, and we used it as a way to research something almost completely on our own for a long period of time, which is something we'd never done before.

I think one of my biggest accomplishments was the assembly of the Sea Perch. My partner Luke and I were given a manual, lengths of PVC pipe, and a kit to help build it. After creating the body of the Sea Perch -- basically a hollowed-out cube of PVC pipe and a net beneath -- we had to solder a small control board. I grabbed my goggles and soldering iron and began the rather tedious process of soldering small pieces onto a plastic control board. At first, I was very worried that I would mess up. Maybe I would solder two pieces together that wouldn't work, or maybe I would inhale to many fumes from the solder melting. But I ended up getting very comfortable with it. After two days of class time and only a single burn, it was finally complete.

After attaching the motors and foam to the Sea Perch, the next step was to test it. We took our Sea Perch (named "Adiane," a water witch from a show my partner and I watched) to the Charles River. That day was warm with a slight breeze, but nothing that stirred the water up too much. We were told to test the Sea Perch on the inner side of the dock, closest to the land. I found a good spot and pulled out my battery and Sea Perch. I connected it to the battery and threw it into the water. For the next half hour or so, I worked to get it to neutral buoyancy by cutting down the foam until it floated but could also sink under the water using one of the motors and then come back up. Once I had, I was able to test it on the outer side. We weren't there to gather any or samples that day -- we really just needed to get used to the mechanisms and play around with them. (We got the opportunity to do so when some stray pieces of foam floated away and we caught them with our Sea Perches!)

Once we got back, each partnership started to work on what question we wanted to answer with our Sea Perch. Luke and I decided that ours would involve testing many different contaminants in the river and then researching what would happen if you drank only Charles River water for a day. And so the next few trips to the river were spent doing just that. We collected samples with a sponge we attached to the Sea Perch and then tested them with small test strips that changed color depending on the levels of what we were testing for. We did run into some challenges; some days were colder or more windy than others, and at one point a roll of electrical tape ended up in the river from the wind, making it hard to connect our sponge to the Sea Perch. Next time we learned to bring more than one roll of tape!

Recently, as the Sea Perch unit comes to an end, we began the more difficult side of the project, which was writing and explaining our results in a lab report. This was a really interesting project, and not only was it fun, it helped me learn to stay organized so that information gathered over the past few months wouldn't be lost. I also learned the importance of choosing a question that I really enjoy, which I'm glad my partner and I did. In fact, we just finished our poster explaining the effects of drinking Charles River water for a day on the human body. (Spoiler alert: they are not good.)