Background & Theory

The majority of deep sea vessels destined for Fraser Port are required to schedule their inbound and outbound times to the tide cycle. Avadepth, an acronym for available depths, was first developed in 1986 for the Canadian Coast Guard, and is designed to assist the mariner in determining the maximum draft and the best sailing times on the river to safely transit the Fraser River - South Arm Channel.

A complete redevelopment of the reporting system was undertaken to increase flexibility and to bring the program in line with current computer technology. The reporting system now enables clients to recalculate depth forecasts to incorporate any significant change in river discharge that can occur daily during periods of heavy rain or during "freshet" - a term used to describe the rising water levels and increased flow conditions during spring run-off of a melting snowpack.

Theory of Operation

Avadepth calculates the depth at any point along the river channel by adding together the effective channel sounding (surveyed depth below nominal low-water level), and the tidal assist (height of the water surface above low-water level), subject to the following time-sensitive restrictions: