Scientists to dive at site of 1922 British naval shipwreck off Labrador

Nearly a century after a British naval vessel ran aground off Labrador, a Dalhousie University professor is preparing a dive expedition to assess the impact of the ship's unexploded munitions on the marine environment and to map the site.

The light cruiser HMS Raleigh drove aground on fog-shrouded rocks below the Point Amour lighthouse in southern Labrador on Aug. 8, 1922, and lost 11 of its more than 700 crew members.

The 184-metre vessel was the pride of Britain's North Atlantic squadron and had been commissioned for service just a year earlier. It was eventually blown up at the grounding site by the British navy in 1926, although much of the ship's ammunition was left behind.

Chris Harvey-Clark, a marine biologist and veterinarian, first dove to document the wreck in 2012.

"The [wreck] was a huge embarrassment to the British," he said in an interview, noting that the ship was moving at a relatively low speed and yet managed to run up onto the rocks beneath a lighthouse.

2nd trip for professor

On this second trip, Harvey-Clark's four-person team will attempt to complete a mapping of the site while sampling marine life in the area such as sea urchins, kelp and mussels for residues of explosives.

"The ship was loaded with something like 80 tonnes of shells that were mostly armed with TNT and some of them with another explosive called picric acid, so we are looking for the metabolites of those chemicals in plants and animals in the area," he said.

Harvey-Clark said while previous work at the site by the Canadian military has removed some of the ship's massive shells, there are still some that remain in the area.

He said the data collected from wildlife and bottom sediment will be compared with that collected in Halifax's Bedford Basin, which saw a "rain of shells" when the Bedford magazine exploded over two days in July 1945.

The shells from HMS Raleigh that have been on the bottom for decades are beginning to break up, Harvey-Clark said. He said the TNT used in artillery shells was melted down and poured like wax into the metal casing.

"If it is in plants or in animals that would graze on the chemical or its residues, then are they actually appearing in other animals further up the food chain? Particularly, we are going to look for crabs ... and we may even take a few fish in the area," he said.

Large wreck site

Harvey-Clark said the wreck site, which runs seven to 14 metres in depth, is roughly the size of two football fields, but it's an area that has likely changed since his last dive because it is constantly battered by strong currents, rough seas and even icebergs.

His first expedition saw just three days suitable for site mapping, but it still managed to locate some key features of the wreck, including one of the ship's propellers, its drive shafts, boilers and ammunition magazines.

Harvey-Clark said with a better weather window and the help of more advanced technology, including a camera-equipped drone, his team should be able to produce a more comprehensive picture this time.

"With the latest map, we actually will produce something [that] I think will help the Department of National Defence in the future when they go to clear ordinance off the wreck," he said.

Harvey-Clark said his team hopes to dive once or twice a day over a two-week period beginning this weekend.