Important Information

Important Note Regarding AHS Products

Australian Hydrographic Service (AHS) products include all significant hydrographic information obtained by the AHS at date of compilation. Significant information is updated by Australian Notices to Mariners.

All reasonable efforts have been made to ensure the accuracy and completeness of the information, including third party information, incorporated in AHS products. The AHS regards the third parties from which it receives information as reliable, however the AHS cannot verify all such information and errors may therefore possibly exist.

Where possible, indications regarding the reliability of information are noted or symbolised in the product. Users should familiarise themselves with the meaning of any notes or symbols. The AHS does not accept liability for errors in third party information or the inappropriate use of published products.

Accuracy and Reliability of Charts and ENC's

How accurate are nautical charts? How much faith can be placed in them? Unfortunately, the answer is quite complex – far more complex than simply saying one chart is accurate whilst another is not.

All charts, whether paper or electronic, contain data which varies in quality due to the age and accuracy of individual surveys. In general, remote areas away from shipping routes tend to be less well surveyed, and less frequently, while areas of high commercial traffic are re-surveyed frequently to very high levels of accuracy, particularly where under-keel clearances are small. It is quite accurate to consider a chart as a jigsaw of individual surveys pieced together to form a single image. Having the necessary skills to determine how much confidence should be placed in the surveys which combine to form a chart should be essential for any mariner venturing into unfamiliar waters.

The attached guide on Accuracy and Reliability of Charts contains both explanations and examples intended to assist mariners in vessels of all sizes to determine how much confidence they should place in charts.

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