74 volumes the suppliments of whose, are published every two , three or five years interval.(R2, R3 & R5 can be obtained from admiralty catalogue.)
Here , R2 means published at 2 years interval.
R3 means published at 3 years interval.
R5 means published at 5 years interval.
- Popularly known as pilots.
- Provide valuable information that may be needed by a mariner regarding any area.
- Various navigable areas all over the world are covered by different ASD volumes.
- A diagrammatic key showing boundaries of geographical areas covered by different volumes may be found in admirality chart catalogue
- Gneral information about any area and knowledge of local regulations, climatic conditions, anchorages, port facilities, harbour approaches etc may be easily acquired by reading the appropriate volume.
- Corrections to ASD are found in section 4 of weekly notices to mariners.
- Those in force at the end of the year are reprinted in the annual notices to mariners.
- Each succesive publication supercedes the previous one.