Serendipity, Sonars and Surveys
The Role of the Canadian Hydrographic Service in the Discovery of HMS Erebus
In the summer of 2014, members of a multi-disciplinary team continued the multi-year search for HMS Erebus and HMS Terror, the lost ships of Sir John Franklin's expedition, which were beset and later abandoned in the ice of Victoria Strait in 1848, west of King William Island. The team discovered HMS Erebus in southern Queen Maud Gulf, generating extensive interest around the world.
Like many pivotal moments in discoveries, it was luck and generosity that set off a chain of historical events that led to the discovery of Captain Franklin's lead ship, starting with the simple act of a CHS hydrographer offering extra helicopter space to a team of Nunavut archaeologists, and ending with a marine survey by the Canadian Hydrographic Service to produce stunning three-dimensional images of the located wreck, images that ultimately enabled Parks Canada's marine archaeologists to confirm the identity of HMS Erebus.
Long gone are the days when hydrographers measured water depth with techniques like lowering a weighted line into the water. Today, the Canadian Hydrographic Service has an astounding array of options for gathering data.
Most of the surveys are now conducted using multibeam sonar technology on survey launches that are either deployed from a ship or from shore.
Multibeam sonar is a cutting-edge technology that transmits hundreds of beams of sound through the water, relaying the information to computers to capture images of the seabed. The images generated from the data allow scientists to "see" underwater dangers to navigation, landscapes, geomorphological features and sometimes wrecks!
On September 1st, a heel of a davit from a British naval ship was found by a helicopter pilot on an island in southern Queen Maud Gulf during a ground survey led by the Government of Nunavut's archaeological team. This clue ultimately lead to the location of the wreck HMS Erebus.
Following the land-based find, Parks Canada marine archaeologists amended their target search area using their own vessel RV Investigator, a smaller vessel launched from CCGS Sir Wilfrid Laurier. It would be the side-scan sonar of RV Investigator that would transmit the first images of a nearly intact ship sitting upright on the ocean floor.
I was called over the ship announcement speakers to my office aboard CCGS Sir Wilfrid Laurier, which in itself is a typical occurrence. When I arrived, the Chief Officer Rich Marriott closed the door behind me and asked me to surrender all of my satellite communications. I knew then what that meant. We had made a discovery. I was astounded. Scott Youngblut – Hydrographer-In-Charge
It then fell to the Canadian Hydrographic Service to collect high resolution bathymetric data using multibeam sonar equipment. This produced never-before-seen images of the wreck, which were used by the marine archaeologists to confirm the identification of the ill-fated expedition's lead ship HMS Erebus!
This is the story of how the Canadian Hydrographic Service set out to collect high definition bathymetric data showing highly detailed images of the seabed in order to make better marine navigation charts and ended up helping to make history.
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