Halifax Explosion
In 1917, Imo sailed as a charter for the Belgian Relief Commission. Being neutral, Imo had on her side the words "Belgian Relief" to protect her from German and Austro-Hungarian submarines.[5] Imo was sailing in ballast (empty) en route to New York to load relief supplies. She reached Halifax on 3 December for neutral inspection, and spent two days in Bedford Basin awaiting bunkering.[6] She was cleared to leave port on 5 December, but was delayed as her bunker coal did not arrive until late that afternoon. Bunkering was not completed until after the anti-submarine nets had been raised for the night, so she could not weigh anchor until the next morning.
Imo had a crew of 39 men, commanded by Captain Haakon From. With a registered length of 430.7 ft but a beam of only 45.2 ft, Imo was long and narrow. Because she was in ballast (without cargo), her propeller and rudder were nearly out of the water, making her hard to steer. She was powered by a triple-expansion steam engine with a single 20-foot right-hand propeller, able to make 60 revolutions per minute. Her propeller gave her a "transverse thrust", i.e. while making headway she veered to the left, in reverse she swung to the right. Under these conditions, Imo was at a disadvantage in navigating in tight quarters. "Due to the combined effect of transverse thrust and the length, and depth of SS Imo's hull, and its keel, she was difficult to maneuver".[5] The guard ship HMCS Acadia signalled Imo clearance to leave Bedford Basin at about 7:30 a.m. on the morning of 6 December,[7] with Pilot William Hayes aboard. Imo entered the Narrows well above the harbour's speed limit, in an attempt to make up for the delay from bunkering.[6] Imo met a US tramp steamer, SS Clara, being piloted up the wrong (western) side of the harbour. The pilots agreed to pass starboard to starboard. Soon afterwards, Imo was forced to head even further towards the Dartmouth shore after passing the tugboat Stella Maris, which was travelling up the harbour to Bedford Basin near mid-channel. Horatio Brannen, captain of Stella Maris, saw Imo approaching at excessive speed and ordered his ship closer to the western shore to avoid an accident.
This incident forced Imo even further over towards the Dartmouth side of the harbour into the path of the oncoming Mont-Blanc, a French cargo ship fully loaded with a highly volatile cargo of wartime explosives. Unable to ground his ship for fear of a shock that would set off his explosive cargo, Pilot Francis Mackey ordered Mont-Blanc to steer hard to port (starboard helm) and crossed the Norwegian ship's bows in a last-second bid to avoid a collision. The two ships were almost parallel to each other, when Imo suddenly sent out three signal blasts, indicating she was reversing her engine. The combination of the cargoless ship's height in the water and the transverse thrust of her right-hand propeller caused the ship's head to swing into Mont-Blanc.[6] At 8:45 a.m., the two ships collided at slow speed in The Narrows of Halifax Harbour.
While the damage to Mont Blanc was not severe, it toppled barrels that broke open and flooded the deck with benzol that quickly flowed into the hold. As Imos engine engaged, she quickly disengaged, which created sparks inside Mont-Blancs hull. These ignited the vapour from the benzol. A fire started at the waterline and travelled quickly up the side of the ship as the benzol spewed out from crushed drums on Mont-Blanc's decks. The fire quickly became uncontrollable. Surrounded by thick black smoke, and fearing she would explode almost immediately, the captain ordered the crew to abandon ship. At 9:04:35 a.m., the out-of-control fire aboard Mont-Blanc finally set off her highly explosive cargo. The ship was completely blown apart and a powerful blast wave radiated away from the explosion at more than 1000 m per second. Temperatures of 5000 C and pressures of thousands of atmospheres accompanied the moment of detonation at the centre of the explosion.[6]
About 1,950 people were killed by debris, fires, or collapsed buildings, and it is estimated that more than 9,000 people were injured.[8] The explosion wrecked the upper decks of Imo. Three of the four personnel on her open bridge were killed: Captain From, Pilot William Hayes and R. Albert Ingvald Iverson, the First Officer. John Johansen, the helmsman, was severely injured but survived. Four other crewmen were also killed: Harold Iverson (seaman), Oscar Kallstrom (fireman), Johannes C. Kersenboom (carpenter) and Gustav Petersen (boatswain).[9] The blast and the tsunami that followed threw the ship ashore on the Dartmouth side of Halifax Harbour.[10] The Wreck Commissioner's Inquiry carried out the official investigation into the cause of the collision. Charles Jost Burchell, a prominent Halifax lawyer, represented Imo's owners as he did in the lengthy civil litigation. The inquiry initially held Imo's crew blameless, and put the entire responsibility for the collision on the Mont-Blanc. However following appeals to the Supreme Court of Canada in May 1919 and the Judicial Committee of the Privy Council on 22 March 1920, both ships were found to have made navigational errors and were found equally at fault for the collision and its consequences.[11]
