Tidal Information

Tidal Products & Publications

For more information on our range of tidal products and publications, please see our Products & Services Publications page or indivdual publications below:

Survey Operations Support

The AHO Tides and Geodetic section determines sounding datum levels for RAN and HIPP Hydrographic surveys. This includes but not limited to providing tidal heights predictions and model reduction method for survey areas using tidal and geodetic collected during the survey.

Hydrographic Office Cartographic Support

Accurate charts cannot be compiled without tidal information. The AHO Tides & Geodetic section determines an appropriate Chart Datum for every chart, supplies tidal and tide stream information for charts, and determines if and where tidal stream information should be shown.

Tidal Information Service

There is a considerable demand for tidal information - especially predictions. The range of requests handled by the AHO Tides & Geodetic section is diverse, supporting such things as offshore resource exploration, scientific study and general inquiries from the public. Simple inquiries can often be addressed quickly and at little or no charge. More complex inquiries or access to certain tidal information will require a formal request and may incur charges or the need to take out a licence.

Lunitidal Intervals

The lunitidal interval is defined as the time interval between the transit of the Moon over the local or Greenwich meridian and the next local high water or low water. It can be described as local or Greenwich, depending on the transit reference meridian; assumed to be local unless otherwise specified.

Lunitidal intervals can be calculated for any location but is meant for places where the semidiurnal component of the tide is dominant.

The lunitidal interval changes through the lunar phase cycle. The variation about the mean is approximately +/- 30 minutes.

Please Note:

  • Lunitidal intervals are considered obsolete and should not be used for navigation or any other critical purpose.
  • Users are advised to use AusTides for higher quality predictions than what is available at: www.bom.gov.au/marine/
  • The State Authorities produce their own Official Tide Tables with time differences for secondary ports.
  • Australian National Tide Tables and AusTides provides National coverage.
  • Automatic Tidal predictions for Secondary ports are available with AusTides.

All locations listed in the Australian National Tide Tables can be found here: Lunitdal Interval 2024 . This table is updated every five years.

Tidal Glossary

There are many words and terms that are used in hydrographic circles. Here is a concise list of terms and their definitions: