The Australian Hydrographic Service is now working with Yachting Australia, Yachting NSW and NSW Maritime to raise awareness of the limitations of the commercially derived charts used within chart plotters and racing software systems. While popular and in common use, fundamentally, all the charts used in these systems are marked as “Not For Navigation” or “Aid to Navigation only” in the various user agreements within them.

This is because there is no guarantee that they faithfully reproduce the details and dangers shown on Australia’s official series of charts. A number of incidents in recent years, including a missing reef ($1.7M yacht destroyed), missing submerged danger, and reportedly even missing islands, as well as GPS and datum problems resulting in vessels apparently being plotted in the wrong place, have highlighted the importance of noting the limitations of these commercially derived charts.

The take home message is simple; these packages are about optimising performance, and for that they are very good. However, they are not intended to be the last word in supporting safe navigation and are not intended to have total reliance for safety placed upon them.

As part of this awareness campaign, the Australian Hydrographic Service has published a number of simple Fact Sheets addressing such issues as learning to interpret how accurate charts are, how to update charts (or tell if you at least have the current edition), how to transfer GPS positions onto non WGS84 charts, and how these commercial charts should be used in conjunction with the official charts that are still required for all offshore races. These Fact Sheets are being progressively distributed by Yachting Australia and Yachting NSW, or can be downloaded free from the Hydrographic Service website at .

Mike Prince

Director Charting Services

Australian Hydrographic Service

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