Man, does that ever bring back memories! I traversed that canal many times when I sailed with Shell and Imperial Oil. As a young guy I was too footloose to stick with it (winter in the North Atlantic also had something to do with that) but one of my friends made a career of it and he's now a captain with BC Ferries.
Here's one of the ships I sailed as an oiler (engine room) transiting the Welland. Note the ice breaking bow - that was for getting through the Labrador Sea and Saint Lawrence River in winter.
http://www.wellandcanal.ca/shiparc/imperial/stclair/stclair.htm
ebear