Halifax 2006

Posted on 15. Mar, 2009 by Greg Mossfeldt in East Coast

Discovery of Shipwrecks off Halifax

By Gordon Fader

Many shipwrecks lie off the rugged south coast of Nova Scotia. Most are the result of sinking during wartime by enemy submarines while others sank through collisions at sea and/or grounding in rough and foggy weather on the many shallow shoals and headlands along the drowned river Nova Scotian coastline.

In recent years, new mapping technology of the Canadian Hydrographic Service and the Geological Survey of Canada using multibeam bathymetry, sidescan sonar systems and high resolution magnetic systems have revealed both the complexity of the seabed on the inner continental shelf and a large number of unexpected magnetic targets that likely represent shipwrecks. The inner shelf of mid-Nova Scotia (largely around the Halifax Harbour entrance) has been mapped by the Geological Survey of Canada as a hard and rugged seabed of exposed bedrock. The overlying surficial sediments are thin and consist mostly of sands and gravels that formed when the post glacial low sea level transgressed the seabed and returned to its former present high stand. As the sea flooded across the inner shelf it removed most of the previously deposited glacial sediments giving the inner shelf it present hard and rough characteristics. These characteristics make the finding of shipwrecks very difficult as the bedrock ridges at the seabed often mimic the shape of shipwrecks and occur in the thousands. It is probably the most difficult seabed in the world on which to find shipwrecks.

Based on the new multibeam mapping, and combined with the magnetic data from surveys in the 1990s collected and processed by geophysist Bosco Loncarevic, a large number of anomalies appeared on the imagery as isolated features. The multibeam systems of the time had a resolution of approximately 5 m so detailed characteristics could not be determined. A program began to assess these features and was led by Gordon Fader of the Geological Survey.

Results of these surveys led to submersible dives using the Canadian Navy facilities and confirmed that most of the magnetic anomalies were indeed shipwrecks. Through this method, the British Freedom, the Clayoquot, the Athel Viking and the Kaaparen were found and confirmed. The total number of magnetic anomalies that likely represent shipwrecks in this area alone numbers 52.

HMSC Clayoquot

This Bangor Class minesweeper was sunk by a German U boat on Dec 25, 1945 off the entrance to Halifax Harbour and was a very difficult shipwreck to find. Gordon Fader of the GSC was on his way to survey the Grand Banks of Newfoundland leaving from Halifax Harbour. It is normal practice to test equipment at the start of the cruise beyond the Harbour mouth in case repairs were needed early in the cruise. He decided to test the sidescan over one of the magnetic anomalies off the Harbour and instructed the navigator on the ship to proceed to mag target # 2 off Halifax as 3 mag targets occurred just off the mouth of the Harbour. It was a very long time before we realized that the navigator actually choose mag target #3 for the shakedown survey and not target #2. He had considered that since the British Freedom had been found it was not target no 1. This led to confusion about the identity of mag target 3 for a few years.

The CCGS Hudson proceeded to launch the sidescan over the mag target and conducted a criss cross survey. Note that on the multibeam there was no clear feature to represent the mag anomaly. The sidescan sonar survey retrieved a clear image of a shipwreck. The shadow of the image showed a destroyed stern, a sharp well-defined bow, a bridge and a gun on the foredeck. Following the cruise, research in the archives suggested that it likely was the Clayoquot. The problem was that we all thought it was at the location of mag anomaly #2 when in fact it was #3.

The final confirmation that it was the Clayoquot occurred when Mike Fletcher of EcoNova dove to the wreck at mag site 3, the wreck defined by the discovery sidescan sonogram. It was filmed for one episode of the Sea Hunters and this production has since been released and aired.

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