Adapting the canal to new needs

After the American Revolution, Loyalist settlement in Upper Canada greatly increased trade with Lower Canada in the early 19th century. Because merchandise moved mainly by water, the British used increasingly larger batteaux and then adopted Durham boats from the United States, whose dimensions far exceeded those of batteaux. Since the St. Lawrence canals had been designed for batteaux, they were too narrow and too shallow for Durham boats. Between 1814 and 1817, the British government spent large sums to enlarge the canals to meet these new navigation needs. Batteaux were rarely more than 12.1 m long and 2.4 m wide, with a carrying capacity of 3 to 5 metric tons, while Durham boats could reach 27.4 m long and 3.65 m wide and carry 10 times as much merchandise. At Coteau-du-Lac, enlargement work between 1814 and 1817 reduced the number of locks from three to two, doubled the canal's width, and increased its navigable depth by about 45 cm through the construction of a jetty more than 80 m long at the upper entrance. Although further changes were made in later years, the size of vessels the canal could accommodate did not change, and it was abandoned around 1850.

Quebec · Canada