Subsea Tech Helps in HMS Erebus Search
Early in September, a team of Canadian underwater archaeologists discovered the wreck of the HMS Erebus in the eastern stretches of the Queen Maud Gulf off the coast of Canada. As part of the search, the team used an array of state-of-the-art technology, including advanced sonar devices, remotely operated vehicles and autonomous underwater vehicles, to at first locate and then capture images of the vessel.
The Erebus, alongside the HMS Terror, was one of the ships of the doomed Franklin Expedition that set out to traverse the last unnavigated section of the Northwest Passage in 1845 – before becoming trapped in ice in the Canadian Arctic, resulting in the death of expedition leader Captain John Franklin and 128 men.
Sonar images of the shipwreck were initially captured by the Klein System 3000, a towed side-scan sonar device deployed alongside the Parks Canada survey vessel Investigator. The sensor was housed in a tow body, or towfish, that trailed behind the Investigator close to the seabed on a 200 metre armoured tow cable. The 3000 series Side-Scan Sonar System is a simultaneous, dual-frequency, single-beam, digital side-scan sonar for use in general seafloor survey applications.
Following the discovery of the exact location, the search team deployed a Falcon Seaeye remotely operated vehicle, to obtain real-time video images of the Erebus. Attached by fibre optic cables to a control unit piloted by senior underwater archaeologist Ryan Harris, the ROV, which is capable of operating at depths of up to 300 metres with a 14 kilogram payload, used a high resolution colour camera on a 180° Tilt Platform to capture the footage.
A key technology used in one of the other search areas was the Arctic Explorer, a seven metre long Autonomous Underwater vehicle (AUV) that Defence Research and Development Canada (DRDC) used to scan the seabed in the vicinity of the lost ships.
Originally developed by British Columbia-based company International Submarine Engineering (ISE) to map the Arctic seabed in support of Canada’s claim under Article 76 of the United Nations Convention on the Law of the Sea, the AUV is a modular vehicle that can be pre-programmed to carry out missions beneath the surface of the sea without any physical connection or communication with a control station. It consists of a forward free-flooding section, full diameter pressure hull and a free flooding aft section.
During the Franklin Expedition search the on-board technology included an ultrahigh-resolution AquaPix Interferometric Synthetic Aperture Sonar (INSAS) produced by Kraken Sonar Systems, which enabled the team to capture high-resolution images at longer ranges than those possible using conventional side-scan
“The Arctic Explorer dove several times leading up to the pinpointing of the downed vessel that was spotted. With the vessel in such shallow waters, the imagery that was disseminated to the masses by government was taken with another towed body device holding a side-scan sonar,” said Linda Mackay, Marketing & Communications Manager at ISE.
“Where ice is the challenge, you can see the advantages of the AUV’s capability to be pre-programmed and to manoeuvre under ice,” she added.