Options for New Ballast Water Rules on the St Lawrence Seaway

by Harry Valentine 

The St Lawrence Seaway provides maritime passage between North America’s Upper Great Lakes and the Atlantic Ocean. During earlier times, ships destined for ports along the St Lawrence River could carry ballast water from other parts of the world. Then some foreign marine species such as the Zebra Mussel became resident along the St Lawrence River and in the Great Lakes. Revised shipping rules required that ships exchange ballast water prior to sailing upriver to points upriver of Montreal.

The environmental department of New York State has announced the intention to enforce new rules for ballast water after 2012. Future ballast water will quite literally have to be of municipal drinking water quality, minus the chlorine and fluoride. The second set of navigation locks upriver of Montreal, the Snell locks and the Eisenhower locks are both located inside the American border and would likely be the location where ballast water will be inspected and analyzed.

The closest dock on the Canadian side of the border capable of serving oceanic ships is at the town of Cornwall, in Eastern Ontario. It was de-commissioned following the closure of several mills in that town that depended on ship transport. However, new rules for ballast water upriver of Cornwall may prompt a possible re-commissioning of the dock facility at the Port of Cornwall. Ships sailing upriver of Montreal may have several possible services in order to transport cargo to ports on the Great Lakes. The options would be:

- Exchange ballast water from a water purification service located at the Cornwall dock. Such companies could rent or sell such water. A ship may take on ultra-clean ballast water on the westbound voyage, then return the ultra-clean water on the eastbound voyage. The water company may rent ultra-pure ballast water for a fee or to sell such water to ships. Cornwall’s close proximity to New York State will allow their environmental officials to regularly visit the water purification service at Cornwall, possibly pre-clearing westbound ships upon their departure from Cornwall.
- Ships may gain the option to transfer cargo to rail transport at Cornwall, except that the railway line that served the Port of Cornwall had been removed. There may be scope to install a new railway line to serve a re-commissioned Port of Cornwall. At the present time, most ship-rail transfers occur at the Port of Montreal.
- Undertake ship-to-ship transfer of cargo and freight at or near Cornwall, from where specialized ships may sail the St Lawrence River without need for ballast water. Such ships would use specially designed, height-adjustable propulsion technology described in the section below.

Ballast-free River Ship:

Most designs of ships require ballast water when sailing on the ocean. It provides stability and keeps propellers and rudders at a depth that assures optimal operational efficiency. Without ballast water, a lightly loaded ship would be unstable at sea and sail with portions of the propeller and rudder riding above water. While ballast water is a crucial necessity for most designs of ocean going ships, it may be possible for ships that sail along inland waterways to sail without need for ballast water.

Flat-bottomed ships that are unsuitable for oceanic sailing may serve well along rivers and inland lakes where wave amplitude is minimal. Such ships sailed the Mississippi River for decades and using this precedent, there may be scope to modify some older oceanic ships to purely inland service along the St Lawrence Seaway and inland lakes. Such a conversion would include the installation of height adjustable propulsive and steering technology that would adjust in relation to the ship. While being totally unsuitable for oceanic service, such technology may be well suited to the calmer waters of inland waterways and lakes.

Height-adjustable azipods with electrically driven propellers that can be raised and lowered with respect to the deck of the ship would provide efficient propulsion and steering functions. A similar height adjustable azipod may be installed under the ship near the bow and function as bow thruster. The low-speed diesel engine would drive electrical generating equipment instead of a propeller shaft and propeller. There may be scope to modify the ship hull to enhance stability for operation along inland waterways.

Modern Stern Paddle Wheeler:

New York State’s new environmental rules for ship ballast water may herald in a new era of a modern stern paddle-wheel riverboat that may sail the St Lawrence Seaway between the Port of Cornwall and ports around the Great Lakes. The modern stern paddle wheeler will borrow propulsive technology from tugboats equipped with vertical axis thrusters, of Voith-Schneider design. These units are capable of providing propulsive effort when operating on either the vertical axis of a tugboat or on the transverse-horizontal axis of a modern paddle wheeler.

The modern transverse-horizontal axis marine thruster would be mounted on a height-adjustable lever system that may be raised or lowered in relation to the deck of the ship. Such a feature would ensure that the working side of the thruster operates close the river floor where it will achieve optimal propulsive efficiency. A deflector mounted near the upper side of the thruster would divert the water stream to the side and away from the drag side of the thruster. Speed restrictions imposed on ships that sail along the St Lawrence River would enable the transverse-axis thruster to achieve competitive propulsive efficiency against the propellers of ocean going ships.

Propellers achieve optimal propulsive efficiency when pushing a given volume flow rate (cubic feet per second) of water at specific RPM when sailing over a specific speed range on the ocean. The speed restrictions along the St Lawrence Seaway result in ship propellers operating at lower RPM and lower propulsive efficiency. Diesel engines operate at peak efficiency when at full load on the open ocean, but operate at reduced efficiency when at part load and restricted speed along an inland waterway. A modern paddle wheel driven ship could operate at comparatively competitive levels of propulsive efficiency along speed restricted inland waterways.

It may be possible to design height-adjustable bow and stern thrusters into a modern riverboat that can sail without ballast water. There may also be scope to design several degrees of steering capability into the height-adjustable assembly that holds the transverse-axis propulsion thruster. While electric motors may drive a thruster that includes steering capability, there may be scope for a mechanical drive system to connect a transversely mounted engine to a thruster without steering capability. One option would be 2-casings on either side of the thruster that house closely-spaced tension rods set at either 90-degrees or 120-degrees apart.

Conclusions:

New York State’s new rules for ballast water aboard ships that sail along the St Lawrence Seaway after 2012 may result in the development of a modern design of river ship with height adjustable propulsion and steering. Such a river ship may sail inland waterways without need to carry ballast water. Oceanic ships that sail along the Seaway may take on ultra-pure ballast water at a re-commissioned Port of Cornwall that may also serve as the eastern terminal for river ships.

Canada’s Federal Department of Transportation has decision power as to whether or not to re-commission the Port of Cornwall. Their willingness to do so would offer ship transport companies the ability to access ballast water of a quality that would comply with New York State’s post-2012 standards. Should the Port of Cornwall remain closed to shipping, Canada’s Federal Transportation Department may ultimately seal the fate of the international shipping along the St Lawrence Seaway.
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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]

 

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