Prospects for Longer Ships on the St Lawrence Seaway

Published Nov 20, 2012 3:14 PM by Harry Valentine

Written by Harry Valentine

Despite the St Lawrence Seaway being a seasonal inland waterway, the maritime route provides an essential transportation service insofar as the economical movement of bulk freight is concerned. While extended length ships of 1200-feet sail the Upper Great Lakes of Lakes Michigan, Superior, Huron and Erie, only Seaway-max ships of 600-feet length sail into Lake Ontario. The United States Army Corps of Engineers (USACE) undertook a study that explored methods by which Panamax-2 series ships could sail into Lake Ontario and perhaps into the Upper Great Lakes.

Environmental opposition cancelled plans to deepen the navigation channels along both the Lower and Upper St Lawrence River. Under the revised plans, only partially laden Panamax-2 ships will sail into the Port of Montreal, transferring cargo to other ships and to the railways at a point near the mouth of the St Lawrence River. The withdrawal of plans to sail Panamax-2 ships into Lake Ontario still keeps the door open to explore other methods by which to enhance the productivity of Seaway-max ships.

Seaway Locks:

A close-up examination of the design and location of navigation locks along the St Lawrence Seaway reveals some interesting possibilities. It appears that the original designers may have realized long ago, that longer ships would sail the seas and the lakes at some future time. There is actually space near all the navigation locks between Montreal and Lake Ontario, to extend the length of the basins at each lock while maintaining the identical beam and draft.

The waves along the St Lawrence River system and in the Great Lakes are a fraction of the amplitude of ocean waves. An extended length Seaway-max ship may carry bulk cargo with minimal complication within the Seaway and Great Lakes system. Much bulk freight moves domestically, between ports located on the Great Lakes and Seaway system. One company actually has an ocean going ship concept on their drawing board and in their computers, that combines the length of a Panamax-2 ship with the draft and beam of a Seaway-max ship.

Such a ship may carry double the payload of a Seaway-max ship, burn about 10% more fuel and require the identical size of crew. During times when low water levels occur in the Great Lakes and along the St Lawrence Seaway, ships are required to sail at part-payload. Such operation reduces the viability of maritime transportation for conventional Seaway-max ships. However, an extended-length Seaway-max ship may still be viable when operating at part-payload. The operation of such a vessel requires that it be possible to length the basins at the navigation locks.

Sailing upriver from Montreal, there are 2-sets of single locks the suburbs of St Lambert and St Catherine, where there space to extend the lock basins. Further upstream at the power dam, there are 2-sets of single locks built at a considerable distance between them, with sufficient space to extend the navigation basins. At Massena NY, there is also substantial distance between the 2-sets of single-step Eisenhower and Snell locks, with space available to lengthen the basins. There is also available space to lengthen the single-step basin at the lock at Iroquois.

Extending the length of basins at navigation locks between Montreal and Iroquois will provide passage for extended length Seaway-max ships to the ports of Ogdensburg NY, Prescott ON, Oshawa ON, Toronto ON, Hamilton ON and St Catherine’s ON. Toronto has the biggest container port on the Great Lakes. Given that only partially laden Panamax-2 ships may sail to the Port of Montreal, there is scope for extended length Seaway-max ships to interline with Panamax-2 ships near the mouth of the St Lawrence River, where ship-to-ship transfers of containers and other cargo may occur.

Coordinated Loading:

A Panamax-2 ship may begin at the port of origin with all Montreal-bound containers being loaded first, followed by all Toronto-bound containers. Upon arrival at the mouth of the St Lawrence River, the Toronto-bound containers are transferred to an extended length Seaway-max ship that will sail to the port of Toronto. While the operation of the Panamax-2 ship realizes economic benefits on the extended length oceanic voyages, the extended length Seaway-max ship may realize economic benefits in domestic transportation. An ocean-capable version of such a ship may also realize economic benefits on some oceanic voyages.

There may be economic benefit for extended length ships to sail between the Upper and Lower Great Lakes, through a modified Welland Canal that connects Lake Ontario and Lake Erie. There are 8-sets of single-step navigation locks in the Welland Canal system, with considerable distance between most of them. While there is available space to extend the length of basins of most locks, there will be some challenge involved in extending the length of basins of all locks. Most of the main ports and terminals around Lake Erie, the Detroit River, the St Clair River, Lake Huron, Lake Michigan and Lake Superior can already accommodate the length of a Panamax-2 ship, even a scaled-down version built to the beam and draft of a Seaway-max ship.

Design Challenge:

The original Seaway-max ships were designed in an era when engineers used slide-rules to perform complex calculations related to mechanical and structural stresses. In the modern era, engineers have access to computers and techniques in finite element analysis to perform far more complex calculations that related to structural stresses. It would be possible for engineers to use modern computer technology to design an inland lake/river ship of equivalent length of a Panamax-2 ship, with the beam and draft of a Seaway-max ship.

There may be scope for modern computer technology to design an ocean-worthy version of such a ship, to carry bulk freight between lake/river ports and east coast American ports. Such a ship may also sail to several European ports, while an oceanic train version of the ship may be able to sail through the Russian side of the Arctic, to access Asian ports. While the Panamax-2 ship may be the standard to sail via the Panama Canal, an extended length version of a Seaway-max ship may serve certain maritime market niches.

Saving Water:

The European barge canal system and the enlarged Panama Canal include side reservoirs at each lock, reducing water usage by 67% when traversing pairs of ships that sail in opposite directions. An examination of the St Lawrence Seaway between Montreal and Lake Ontario suggests that there may be sufficient space available at each lock basin, to build a side reservoir whenever the lock basins are lengthened. A lock basin of double the length that includes a side reservoir may reduce water usage by 33% over present operations.


There is much environmental opposition to dredge-deepening the navigation channels along the St Lawrence Seaway system to accommodate Panamx-2 ships. The same environmentalists seem unperturbed at the prospect of extended length Seaway-max ships built to the length of Panamax-2 ships, sailing along the St Lawrence Seaway. There is much economic benefit to be gained by extending the basins along the St Lawrence Seaway, for the purpose of allowing passage to extended length ships and Mississippi-style coupled barge-trains.


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About the Author

Mr. Valentine holds a degree in mechanical engineering from Carleton University, Ottawa, Canada, with specialization in thermodynamics (energy conversion) and transportation technology.

He served as a research assistant to Dr Ata Khan, professor of transportation engineering who is still on staff at Carleton University.  Mr. Valentine has a background in free-market economics and has worked as a technical journalist for the past 10-years in the energy and transportation industries.

Over a period of 20 years he has undertaken extensive research, authored and published numerous technical articles in the field of transportation energy.  His economics commentaries have included several articles on issues that pertain to electric power generation.

Mr. Valentine has technical journalistic experience covering low-grade and high-grade geothermal energy, steam generators (with continuous blow down to keep the boiler water clean), engine exhausts, solar thermal (low-grade and low-grade thermal), nuclear and coal-fired thermal steam-power stations. He can be reached at [email protected].

MarEx does not necessarily endorse any opinions herein.

The opinions expressed herein are the author's and not necessarily those of The Maritime Executive.