The Navigation Acts were a complex set of British laws dating from 1651 and 1660, regulating British and later imperial shipping and trade to foster economic and naval power (see mercantilism). They governed ownership and crew nationality of vessels trading to Britain and her colonies, and the acceptability of routes and commodities. They were used to try to link British North America economically with the West Indian colonies; more generally, trade among BNA colonies and theirs with Britain had to be conducted in British or colonial vessels. Trade on the Great Lakes did not entirely fit the system; enforcement was lax before 1815 and by 1822 legislation permitted cross-lake trade in many commodities. Following repeal of the Corn Laws in 1846, Canadians resentfully denounced the Acts as a burden. They were repealed in 1849 as part of Britain's overall movement to free trade.