Q&A: 20,000 leagues under the sea with SeaBotix

We had a lot of interest in the last blog post from SeaBotix, which included many questions about the underwater robot, or remotely operated vehicle (ROV), so we went back to Jesse Rodocker (the star of the recent behind the scenes at SeaBotix video) to ask him some of your questions about his underwater adventures, SeaBotix and their ROV designs.

How low can SeaBotix go?

One topic people were particularly interested was depth. How deep in the ocean can an ROV travel? Jesse let us know that SeaBotix ROVs are rated to several depths including 150m, 200m, 300m, 950m and 4,000m. Some ROVs can even explore as far as full ocean depth – truly where no man has gone before.

Why is the tethered cord necessary?

The tethered cord is another common item of interest. It reminds me of radio control vs. remote control cars. In the toy comparison I always felt let down when I was trying to drive a truck that happened to be tethered to a remote. In the ROV world, the tether actually provides an advantage. The cable allows for capabilities that would otherwise not be at the user’s disposal, such as ROV telemetry, sensor data (sonar, pressure, temperature), video, support for recoveries and continuous power. Score one for the tether.

What’s the most exciting discovery you’ve made with the ROV?

SeaBotix ROVs have made several interesting and exciting finds – it’s not all old shoes and license plates. After speaking with Jesse, he filled us in on one of his favorites, surveying a World War II Japanese Midget submarine outside of Sydney Harbor. These small two-person vessels could travel relatively undetected, but of the three submarines to invade Sydney Harbor two were destroyed almost immediately and the third that torpedoed the HMAS Kuttabul was not found until 2006. In 2009, SeaBotix was commissioned by the government to explore the wreck. Read more about the survey here.

How does the ROV use sonar?

Some of you were interested in how SeaBotix uses sonar during its missions. Jesse was able to shed some light on sonar’s contributions. “Rarely in water is the visibility good enough to see something with just an optical camera. Use of sonar is like radar or night vision and extends your vision out to 50-100 meters and in virtually any water condition. You lock on to a target at long range with the sonar and navigate until close enough to see with the camera.”

How does the ROV interact with wildlife?

One interesting item you asked about was how the ROV interacts with the locals. How does marine life take to an underwater drone visiting their neighborhood? Jesse confirmed that the ROV poses no threat to marine life. In fact, the sea creatures often come over to the ROV to have a look – as was seen during the midget submarine mission in Sydney Harbor. SeaBotix also tests frequencies from sonar and other equipment to be certain that animals are safe. Testing has not uncovered any issues.

How do you avoid common underwater obstacles?

Finally, some of the aspiring underwater adventurers in our community were interested in understanding the main obstacles that you need to look out for during a mission. No one wants to be surprised under the ocean. Jesse identified four big items his team always keeps in mind:

• Know where you are under the water. We have to rely on acoustics for positioning and it tends to be approximate. You don’t know what is down there and what your ROV might get caught in.
• Current. The ROVs can only handle small amounts of current or they can’t maneuver. Less than 3 knots and most commonly less than 2 knots.
• Tether.  It does get in the way and get caught/entangled on structures or objects.
• Topside vessel stability.  If the boat can’t stay still then the ROV gets pulled around.

Thanks for all of the questions. Now you’re ready to be a regular Captain Nemo, but if you still need answers to all of your SOLIDWORKS questions, you can find the solutions at My.Solidworks.com.