Tide and Current Predictions



Raymarine Navigation System




 

PC Coastal Explorer Navigation Software

During our travels north of Vancouver Island, we have noticed that there is a discrepancy between the different sources that provide tide level predictions and current flow predictions for the northern waters of British Columbia.  We use three different sources to obtain tide and current predictions:  1) our Raymarine Navigation System, which has built-in tide level and current flow predictions;  2) our Personal Computer Coastal Explorer Navigation software; and  3) the printed tables issued by Fisheries and Oceans of Canada.  All three sources show different prediction times which are off by an hour or more.  After some investigation, we discovered the following:  1) the built-in predictions for the Raymarine equipment is configured with the incorrect off-set from Greenwich Mean Time so it has an error of 1 hour too early;  2) the Coastal Explorer PC software uses Alaska based reference stations (Alaska time zone) for its calculations so predictions are 1 hour later than they should be;  3) the government printed Fisheries & Oceans Tables are extremely limited in the number of locations that provide predictions.  To confirm his speculation and research, Leonard called the Coastal Explorer software service department regarding the time discrepancy for predictions in northern B.C. waters.  He was told that they are aware of the Alaska time zone issue for the northern B.C. waters and are making corrections to the PC software.  As it stands, we adjust the Coastal Explorer predictions by one hour, knowing that it is one hour late; and adjust the Raymarine prediction, knowing that it is one hour too early; and then cross-reference with the government Printed Tables for comparison.  Sometimes boating is a little more complicated than it first appears.



Government Printed Tide & Current Tables