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Nashua;56.0;http://forecast.weather.gov/images/wtf/small/skc.png;2014-11-25 16:50:11
Tuesday, January 15, 2013

Sonar doesn't work through ice, so lost-snowmobile lake search will require a robot sub

The Maine Warden Service says it will probably have to use a remote controlled sub to search Rangely Lake for three snowmobilers who are believed to have broken through the ice. The lake's too big for random search by divers, and according to this Maine Morning Sentinel story, sonar doesn't work through ice. I didn't realize that.

I can't find anything more specific about the submersible they use - whethered it's tethered or truly autonomous. I have a call into the department to find out more; when it shows up, I'll let you know.

UPDATE from Maine Warden Service, Corp. John MacDonald:

As a supplement to the press release sent yesterday regarding the recovery effort on Rangeley Lake, the Maine Warden Service will clarify the planned use of the Underwater Remotely Operated Vehicle (UROV). In order to deploy the UROV, ice conditions must be thick enough to support operations from on top of the ice. The currently ice conditions do not allow UROV work to be performed. Conditions might not permit UROV deployment until February.

When and if ice conditions become safe, a large hole will need to be cut in the ice, warming tents will need to be erected on the ice (for equipment and personnel), and other pieces of equipment will need to be staged on the ice for operational purposes and safety. When and if clear, identifiable targets are located with the UROV, an assessment will be made for retrieval by divers. SONAR use will have to wait until open water forms this spring.

The UROV is an Outland 1000. It is a tethered unit controlled from the surface with 500 feet of cable. It has a grabber arm attachment, two cameras, two LED lights as well as obstacle avoidance sonar.