Shipwreck City of Genoa examined by ultra-high resolution underwater lidar in southern Lake Huron

An ASI survey vessel

By Linden Brinks

Geospatial Analyst at the Great Lakes Observing System

Part of the Great Lakes Bottom Mapping Working Group Winter 2021 Underwater Update newsletter. Subscribe here.

Last November, the Great Lakes Observing System (GLOS) partnered with ASI Group and 2G Robotics to perform a dual-purpose survey of a portion of southern Lake Huron, including the wreck of the City of Genoa.

In support of Lakebed 2030, GLOS tasked the crew with both a surface survey using ship-mounted sonar and an ultra-high resolution laser survey using a remotely operated vehicle (ROV). Laser surveys represent a type of newer mapping technology that can improve understanding of underwater features and benthic habitats by creating extremely detailed 3D images. 

The test site for this mission was in southern Lake Huron where the ill-fated City of Genoa steamship was hauled after wrecking in 1911 near Sarnia, Ontario.

Over the course of three days and 27 surveying hours, the team collected high-resolution sonar data of the lakefloor using an R2 Sonics 2420. After collecting sonar data, they deployed a remotely operated vehicle (ROV) with an ultra-high resolution laser scanner—a 2G Robotics ULS-500. This type of data, combined with data captured from the lake surface, allows modelers the ability to see the whole wreck in context, with accuracy and a level of detail unattainable without this cutting edge technology.  

After the ASI Group crew returned to base, the work of processing all the data collected could begin. This involves using specialized software to systematically eliminate errors in the data, correct for water temperature fluctuations, and other errors associated with timing, vessel positioning, and GPS signals. The data is now available to demonstrate the benefits of high and ultra-high density sonar and laser data in improving understanding of wrecks and other human-made artifacts, the changing lakefloor, and benthic habitat.

Once the wreck was located, the crew used a multibeam sonar system to do a first scan. 
The blue and green paths show where the ROV collected laser data on top of the greyscale, lower-resolution multibeam data.
A closeup of the laser data. Image by 2G Robotics

For more information about this project, GLOS or the Lakebed 2030, please get in touch with the Great Lakes Observing System at

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