The term Seawaymax refers to vessels which are the maximum size that can fit through the canal locks
A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water level ...
of the St. Lawrence Seaway
The Saint Lawrence Seaway (french: la Voie Maritime du Saint-Laurent) is a system of locks, canal
Canals are waterways Channel (geography), channels, or artificial waterways, for water conveyance, or to service water transport vehicle ...
, linking the inland Great Lakes of North America with the Atlantic Ocean.
Seawaymax vessels are in length, wide, and have a draft of and a height above the waterline of . A number of lake freighter
Lake freighters, or lakers, are bulk carrier vessels that ply the Great Lakes of North America. These vessels are traditionally called boats, although classified as ships.
Since the late 19th century, lakers have carried bulk cargoes of materials ...
s larger than this size cruise the Great Lakes
The Great Lakes also called the Great Lakes of North America or the Laurentian Great Lakes, is a series of large interconnected freshwater lake
A lake is an area filled with water, localized in a basin, surrounded by land
Land ...
and cannot pass through to the . The size of the locks limits the size of the ships which can pass and so limits the size of the cargoes they can carry. The record tonnage for one vessel on the Seaway is 28,502 tons of iron ore while the record through the larger locks of the 
Great Lakes Waterway
300px, The Soo Locks between Lake Superior and the St. Marys River (Michigan-Ontario), St. Marys River
The Great Lakes Waterway (GLW) is a system of natural channels and artificial canals which enable navigation between the North American Great ...
is 72,351 tons. Most new lake vessels, however, are constructed to the Seawaymax limit to enhance versatility by allowing the possibility of off-Lakes use.
See also
* Canso Canal, a Seawaymax passage in Nova Scotia * SS ''Edmund Fitzgerald'', the first ship constructed close to Seawaymax sizeReferences
External links
Ship sizes
{{Ship measurements Ship types Saint Lawrence Seaway Ship measurements +