By: Jacqueline Rosa
In preparation for launching a remotely operated vehicle (ROV)-based community science assessment, the Blue Latitudes Foundation (BLF) has spent the past few months pilot testing and learning how to operate Deep Trekker’s DTG3 ROV . Complete with a 50-meter tether and weighing just under 19 lbs., this portable, commercial-grade ROV is an incredible tool for underwater exploration. BLF’s community science program will incorporate volunteer scientists and ROVs to assess the health and productivity of California reef habitat.
The first phase of DTG3 pilot tests took place in the controlled environment of our neighborhood pool, where calm water conditions and visibility allowed us to keep a close eye on the ROV. Achieving neutral buoyancy was the first objective when placing the DTG3 into water. Because bodies of water can have varying densities depending on their salinity levels, the weight, or ‘ballast’ of the ROV needed to be adjusted accordingly. A neutrally buoyant ROV will maintain its sampling depth, neither sinking nor floating to the surface. The DTG3 model includes small weights that can be added or subtracted to adjust the overall weight. After a few rounds of trial and error, our team successfully balanced the DTG3. Next, we tested driving the ROV at various speeds and determined an ideal sampling speed (1 meter/ second) that would allow for careful observation. As the DTG3 cruised around the pool, we engaged the internal LED floodlights and experimented with capturing underwater photos and videos. A handy ‘camera lock’ function allows the driver to lock the camera angle during use, keeping the bottom in view.
From the view of the ROV camera… the BLF team at their first pool dive!
The next stop for our pilot tests was Mission Bay, located in San Diego, California. This setting presented new challenges for the DTG3, including saltwater, tides, and currents. Because objects in saltwater are more buoyant than objects in freshwater, additional weights were added to the DTG3 before launching into Mission Bay. Once in the water, the sandy bottom and bright green eelgrass came into view. We quickly noted an outgoing tide was impacting ROV maneuverability. To combat this current, the speed and steering settings were adjusted to give the driver better control.
Setting up the DTG3 ROV for a dive in Mission Bay, San Diego
Two important controls were also put to the test in Mission Bay: ‘auto-heading’ and ‘auto-depth’. Setting an ‘auto-heading’ allows the driver to select a compass heading and maintain direction while completing a transect. A transect is a pre-determined path at which data collection takes place. In the future, our transects will take place at different depths in the ocean, depending on how deep a natural or artificial reef is. When utilizing ‘auto-depth’, the ROV is set to fly at a consistent depth in the water column. Combining these two controls, our team practiced driving transect lines along the seafloor.
Next Steps
Equipped with knowledge from our preliminary dives, we plan to launch in the DTG3 in the open ocean next and explore the offshore reefs in San Diego. While operating the DTG3 is more challenging than we initially predicted, each dive presents an opportunity for improvement. As we move along the learning curve, we continue to fine-tune our protocols and carefully design surveys for our future community science work. Our team is excited to connect community members, from students to SCUBA divers, with ROV technology and eventually guide groups in DTG3 navigation.