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Customer Advisories 2012

Draught Information System

The St. Lawrence Seaway is a vital link in one of the major inland waterways in the world, connecting inland ports in the United States and Canada on the Great Lakes to the Atlantic Ocean through the St. Lawrence River.  Shipping on the Seaway is limited by the draught and size of the ships that can navigate the canals and locks.  The safety of navigation on the St. Lawrence Seaway is increased by providing the mariner with better information about under-keel clearance as they make maximum use of the available water column.

The St. Lawrence Seaway Management and Development Corporations (The St. Lawrence Seaway) in cooperation with the shipping industry are developing a Draught Information System to increase the safety of navigation by providing the mariner with better information about under-keel clearance.  High resolution bathymetry combined with current water level measurements and information about ship dynamics allow for under keel conditions to be predicted ahead of the vessel in motion.  Studies have been completed on the behaviour of different classes of vessels with respect to ‘squat’ (the lowering of a moving vessel in water due to fluid dynamic effects).

In March 2011, an initial Implementation Specification for the Draught Information System was published, and in July 2011, proposed revisions to the Implementation Specifications were posted for comments.  Since then, all comments received were addressed, and the revised Implementation Specification is now available at the link below.  A test data set has also been developed and is available upon request for validation of functionality and/or certification of a Draught Information System.   Requests for the test data set may be submitted by email to, to The St. Lawrence Seaway Management Corporation (Attention: L. Lefebvre) or to the Saint Lawrence Seaway Development Corporation (Attention:  T. Lavigne).


February 15, 2012