ACC’s ROV used for dock assessment
ALPENA -Alpena Community College Marine Technology instructor David Cummins recently worked with Thunder Bay National Marine Sanctuary staff and city building, harbor and zoning official Don Gilmet to use the ACC remotely operated vehicle (ROV) in an underwater inspection of the Alpena Municipal Fueling Dock.
“We’ve had an issue with the main dock and the floaters,” Gilmet said. “We talked to Russ Green at the sanctuary, and he suggested talking to the college to see if they could use their ROV to check it out.”
The dock has had a noticible slope downward to one side, and city officials were unsure what was causing the slope.
“They asked us to check out what was causing the slope using the ACC ROV, and to go underneath the dock and see what we could see,” Cummins said. “We found underneath the dock that one side had three tanks attached and the other side only had two tanks. Using the new imaging sonar we have, we were able to measure the tanks. We got a size of around two foot in diameter and five foot long, and got an idea of what the tanks looked like with their fittings on the bottom and side.”
With only two tanks on one side of the dock, Cummins said there is an assumption that the third tank on the sloping side had disappeared.
“We went through and used the sonar and swept to see if it was there somewhere, and couldn’t find it,” Cummins said. “Then, looking at the tanks that are currently there, we noticed a little dip in the tank that was there on the side of the missing tank. The tank had a big dent in it, and looking closer, it had a crack in it.”
The shape of the dent in the tank matches that of a large rock located beneath the dock, and Cummins suggested that with low water levels last year, the tank could have hit the rock and dented and cracked it.
“That tank is probably flooded,” Cummins said. “Each tank has about 800 pounds of upward force, so if it’s missing a tank and the other tank is completely flooded, that dock could be missing 1,600 pounds of upward force.”
It took around an hour for the robot to assess the issues with the dock, and ACC did it for the experience of a real-world scenario to use the ROV. If the project had been contracted out to a company, it would have cost the city over $1,000.
“They made a video of underneath the dock, and now with the use of the video, we can have a plan of attack,” Gilmet said. ” It was a great way to use the modern technology, and worked very good for us. Just them doing that saved us over $500 or more.”
Suggestions to repair the dock would be to replace the dented tank and add another tank in place of the one that is missing. Cummins also suggested checking the existing tanks for any weaknesses or fastening issues.
“It was a great opportunity to show how the technology can be used and how it is used in industrial application for doing investigation analysis, and how you can use it to find a problem and fix that problem,” Cummins said. “Now divers will know what to look for and what needs to be done to repair the dock.”
The college will use this as a real-life application scenario for students to repeat and learn from to better prepare them for the workforce.
With teams from around the world in Alpena competing in the the International ROV Competition this weekend, this practical application is just one example of the way an ROV can be used to investigate and solve a wide range of functions that are useful locally.
Gilmet said he was very pleased with the ROVs work, and if the city ever had a need for it, there are a lot of things they could use it for.
“We could use the ROV to look at issues underwater and use the students to check it out for the city,” Gilmet said. “It was just an excellent way to get a look at what was going on.”
Nicole Grulke can be reached via email at email@example.com or by phone at 358-5687. Follow Nicole on Twitter @ng_alpenanews.