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Great Lakes Ships & Carriers

The Great Lakes - St. Lawrence Seaway navigation system is dominated by specialty ships designed to serve the region's agricultural and manufacturing economy. These vessels transport large quantities of bulk cargo such as iron ore for the steel industry, coal for power generation, stone for construction, and grain for domestic and overseas consumption. Other Great Lakes ships are designed for general cargoes such as machinery, steel and bagged food products. Still others are more specialized as tug and workboats, tankers, and ferries.


Under international law, every commercial vessel must be registered ("documented") in one country or another. The nation in which a ship is registered is referred to as its "flag state," and the vessel will literally fly the flag of its country of registration. The flag state establishes and enforces a regulatory regime governing ownership, safety, administrative, technical and labor matters aboard ship. Most Great Lakes vessels are either documented in the United States (referred to as "U.S.-flag ships"), or in Canada (referred to as "Canadian-flag ships"). Vessels visiting the Great Lakes from overseas are typically registered in any one of a number of other flag states (referred to as "foreign-flag ships").


Cabotage laws reserve the transportation of freight between two ports within a country to those vessels registered under the flag of that country. Both the United States and Canada have cabotage laws. Consequently, the movement of freight between U.S. ports is strictly reserved for U.S.-flag ships. Likewise, the movement of freight between Canadian ports is generally reserved for Canadian-flag ships. The movement of freight between Canada and the United States is unrestricted and may be transported by a U.S.-flag ships, a Canadian-flag ships or a foreign-flag ships.

Vessel Size

The efficiency of a vessel increases with its carrying capacity. For that reason, ship owners seek to maximize vessel size within the constraints of the navigation system. In the Great Lakes- St Lawrence Seaway System, lock infrastructure provides a specific constraint.

St. Lawrence Seaway locks measure 233.5 m (766 feet) long x 24 m (80 feet) wide x 9.14 m (30 feet) deep. Therefore, many vessels have been constructed to "Seawaymax" dimensions. These vessels measure 226 m (740 feet) in length and 24 m (78 feet) in width and have a draft of 7.92 m (26.5 feet).

The Soo Locks in northern Michigan are larger. At that location, the largest lock chamber is 366 m (1200 feet) long x 34 m (110 feet) wide x 10 m (32 feet) deep. Several ships have been constructed to take full advantage of these dimensions. These ships are referred to as "1000 footers," the largest of which is 309 m (1013 feet) in length and 32 m (105 feet) in width. Because of their size, 1000 footers are only able to operate in the four upper Lakes (Superior, Huron, Michigan and Erie), being too large to fit through the TSt. Lawrence Seaway locks.

Vessel Types

  • Lake Vessels ("Lakers")
    Lakers have been designed and constructed specifically to transport dry bulk cargo in the Great Lakes- St Lawrence Seaway System. They have been designed to endure weather, wave action and ice conditions unique to the Great Lakes and are not structurally capable or legally authorized to operate on the open ocean.
    • Self-Unloaders
      Most Lakers have been equipped with self-unloading technology, which enables the crew to unload the vessel without the need for shore-side personnel or equipment. Self-unloading vessels are distinctive in appearance and feature a large steel boom extending down the deck from the ship's superstructure. When unloading, cargo is released through gates at the bottom of the cargo hold onto conveyor belts running below. Bulk material is carried along the conveyor belts and lifted up and out onto the adjacent dock via the pivoting boom.
    • Straight-Deckers
      A handful of Lakers do not feature self-unloading technology and are referred to as "straight deckers" or "bulkers." These vessels require shore-side equipment such as a gantry crane to unload their cargo.
  • Ocean-going Vessels ("Salties")
    Most ocean-going vessels serving the Great Lakes - St. Lawrence Seaway System are designed to handle either dry bulk or breakbulk cargo. For example, a saltie might carry a cargo of steel products into the Great Lakes and export a cargo of bulk grain. Unlike Lakers, salties are designed to handle both Lake and ocean conditions and may operate almost anywhere in the world.
  • Tankers
    Tankers are vessels designed to carry liquid bulk cargo, such as petroleum products. Most tankers operating on the Great Lakes - St Lawrence Seaway System are designed exclusively for Great Lakes service; however, several have the capability to operate overseas.
  • Tug-Barges

    Barges are unpowered vessels that need to be towed or pushed by tugboats. A number of companies operate purpose-built tug-barge fleets on the Great Lakes - St. Lawrence Seaway system that are well suited for the transportation of bulk, breakbulk and project cargo.

    A number of vessel operators have converted former self-propelled Lakers into large barges. These reconfigured vessels have had their superstructure and engines removed. Powerful tugs fit into a notch at the stern (rear) of the vessel and provide propulsion. This tug-barge vessel configuration provides added flexibility in manning and cargo handling.

    River barge operators also serve Great Lakes ports. Since the 1970s, the U.S. Coast Guard has allowed limited river barge operations in southern Lake Michigan. The U.S. inland river navigation system connects to the Great Lakes navigation system at Chicago. Through this gateway, river barge activity has developed into a significant trade serving heavy industry in that region.

The Next Generation of Great Lakes - St Lawrence Seaway Vessels: Significant Environmental Benefits

Shipowners are investing more than $1 billion (CAD) to bring a new generation of super efficient, environmentally-friendly ships to the Great Lakes - St Lawrence Seaway System over the next three years. These first-class vessels, which include both ocean-going and domestic ships, will have the latest engine technology and hull design to increase fuel efficiency and decrease air emissions; double hulls to prevent spills in the event of an accident and state-of-the-art cargo handling systems to minimize dust and cargo residue.

The new domestic Great Lakesships will emit up to 60 percent fewer emissions than the oldest steamships still operating on the Great Lakes and up to 40 percent lower emissions than existing motor vessels. The new ships have been designed to accommodate future installation of engine-exhaust gas scrubbers, equipment that will further reduce emissions. 

Leading ocean ship operators serving the Great Lakes - St Lawrence Seaway System have also announced new investments. These new vessels consume up to 28 percent less fuel and produce up to 28 percent less greenhouse gas emissions than the previous class of ships. The vessels are also equipped with Tier II engines, which will significantly reduce nitrogen oxide (NOx) emissions. The ships incorporate more powerful ballast pumps and have been designed to accommodate future installation of ballast water treatment equipment.

Great Lakes Vessels and Ships - Marine DeliversLakes Vessels ("Lakers")

Great Lakes Straight Decker Ships - Marine DeliversStraight-Deckers

Ocean Going Vessels - Salties - Marine Delivers Ocean-going Vessels ("Salties")

Great Lakes Tankers - Marine Delivers Tankers

Great Lakes Tug Bargers - Marine Delivers Tug-Bargers