Northern Transportation Company - Mackenzie River Navigation and The "Radium Line"

Mackenzie River Navigation and The "Radium Line"

In 1937 the Northern Transportation Company started to introduce new diesel powered steel tugboats to tow barges on the Mackenzie River. The first two vessels were the Radium Queen and Radium King. Other vessels in this fleet included the Radium Express, Radium Yellowknife, Radium Prince, Radium Cruiser, Radium Scout, Radium Charles, Radium Gilbert and Radium Lad, earning the fleet the name "The Radium Line". Port Radium on Great Bear Lake, a mine that supplied much of the uranium used by the Manhattan Project, was a key destination for the fleet.

The tugs were constructed in eastern shipyards, then disassembled, so the parts could be shipped by rail to Waterways, Alberta, a river port on the Clearwater River, which was then the northern terminus of the North American railway grid. The Radium Queen was reassembled there. From Waterways tugs could only navigate the Clearwater, Lake Athabasca, and some of its tributaries. The Slave River, that drained Lake Athabasca to Great Slave Lake, had a 16 mi (26 km) stretch of rapids that had to be portaged around, at Fort Smith, Northwest Territories. The Radium Queen towed the parts of the Radium King to Fort Smith, where they were portaged, and reassembled on the lower river. Most of the fleet were reassembled on the lower Slave River.

Ice on the Mackenzie River, and her tributaries, impeded navigation until early June. Freeze-up occurs in mid October, providing only a few months of navigation.

All of the tugs had extremely shallow draft, and mounted their propellers in cavities under their hull.