Charting and learning on Bay, marina

October 20, 2011 - via Alpena News

ALPENA - Sideways rain and 25 mile-per-hour winds could not keep the Coast Survey team indoors for long Wednesday. Most of the members traveled a long way from Silver Spring, Md., and Pacific Northwest National Oceanic and Atmospheric Administration locations and were determined to get the job done, shivering and all.

The team has been in Alpena all this week and will be wrapping up their work with autonomous underwater vehicles today. They joined a navigational response team who has already been at the Thunder Bay National Marine Sanctuary for the last three seasons.

"With them here, it got us talking and involved much more with Coast Survey. They mentioned their AUV team needed a place to train," sanctuary deputy superintendent Russ Green said. "From NOAA's perspective, it's a great use of resources. The AUV team needs proficiency training, and the sanctuary can provide a research vessel, staff and the shore side infrastructure to facilitate that."

The battery-operated AUVs are programmed to gather data from the seafloor and create nautical charts. The main benefit of this week's surveying is to prepare for the aftermath of storms, where an AUV could be launched into the water and track fallen debris that might harm a vessel.

"Geologists and habitat mappers can use the data as well, it's not just for hazards," said Steve Brodet, who was training Nick Forfinski and Ian Colvert to become expert AUV operators.

Brodet showed a series of side scan images the AUV had retrieved on Tuesday's mission in Thunder Bay. The copper-colored digital pictures were able to capture something as detailed as a rock or a fish stake that had been used years ago to secure large fishing nets underwater. The images even were able to pick up "wind-driven currents" and the curve of a fish's fin.

"These are good," Brodet said, meaning they were clear something he wasn't very used to seeing in Maryland. "There is no impact from ocenographic properties."

The particular AUV the team used this week was depth rated to 100 meters, but team leader Rob Downs said there is no standard depth or size to the vehicles. They range from 7-9 inches in diameter to 29 inches and can dive up to thousands of meters beneath the surface. Running at three knots, Downs said the battery charge can last about eight hours.

The poor weather conditions on Wednesday forced the team into the confines of the marina, where they keyed in information on computers located in a stationary boat docked to a pier. Downs stressed how important it was to be accurate with the directions given to the vehicles. They only do what they are told, which as it turns out, is quite a lot.

Downs has taken the AUVs to Puerto Rico to identify potential munitions objects on a beach site that was used to test bombs. He also brought them to the Florida Keys, where they tracked down illegal lobster habitats poachers were building out of corrugated tin squares, called "casitas," meaning little houses.

"There was some concern it was affecting (the lobsters') life cycles," Downs said. "They tried using boats, but poachers saw them. We brought the AUVs to be more stealthy."

Downs said in 14 square kilometers of water, over 100 objects were detected on the sea floor, and over 60 were probable casitas. The fisheries police got involved, and one poacher was tied to the habitat and prosecuted.
Colvert was challenged with the first trial run around the marina Wednesday morning. He determined depths the AUV should hit and at what speed. A GPS connected to a large tripod was used to measure the marina's dimensions.

After keying in numbers to power the AUV, Colvert was ready for Brodet and Downs to double-check his work, and nearing noon, it was time to get the AUV wet. It took several members to hoist the vehicle out of its case and into the water where it would perform an 18-minute "dead reckoning" loop around the harbor at 2.5 knots. The shallowness of the marina was a worry for the success of the first run being 6-9 feet deep in most areas not to mention the rough winds. But Brodet's "wicked exciting" comment spoke for the whole team as they launched the AUV and scurried up and down the piers to keep up with its course.

Worsened weather conditions Thursday kept the survey team warm inside reviewing Wednesday's collected data.
"There was only one really significant item, it looks like a cement block," said Downs, describing the object to be 1.5-by-1.5 meters and almost a meter tall, located off of the boat ramp. He said the marina's shallow water and the AUV's coasting along the surface kept the data from reading very well.

"Even with the weather being lousy, we're able to get some pretty useful data that we can use to manage shipwrecks," Green said. "Other agencies such as the DNR and US Fish and Wildlife Service can make use of the detailed maps of the lake bottom."

The team is gearing up for one final day on the water, and today's forecast is looking good enough to take the boats out.

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Author:Jessica Nikolich

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