St. Lawrence Seawaymax (Seawaymax)

Seawaymax is the largest ship that can pass the locks of the St. Lawrence Seaway, the limit on ocean access to the upper Great Lakes. The binding figures are 225.6 meters length overall, 23.8 meters beam, 8.08 meters draft, and about 35.5 meters air draft, with deadweight around 28,500 dwt. The constraint is the lock chambers, six on the St. Lawrence River and eight on the Welland Canal that bypasses Niagara Falls. Larger lake freighters exist but stay above the Welland and cannot reach salt water. The Equinox-class self-unloaders, named for their 740-foot length, are built to the maximum the Welland locks accept.