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Customer Advisories 2016

Draught Information System

The St. Lawrence Seaway Management and Development Corporations (The St. Lawrence Seaway) in cooperation with the shipping industry developed a Draught Information System to increase the safety of navigation by providing the mariners with better information about under-keel clearance as they make maximum use of the available water column.  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.

In February 2012, an Implementation Specification for the Draught Information System was published.   This system has since been installed onboard many vessels regularly transiting the Seaway.  More recently, a typographical error was discovered in the dynamic squat equation for traditional laker type vessels resulting in an overestimation of the amount of squat in a shallow lake.  The revised Implementation Specification with the correction is now available at the link below.

A test data set is also 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: S. Grady) or to the Saint Lawrence Seaway Development Corporation (Attention:  T. Lavigne).


November 8, 2016