Hydrographic Note Information

Forwarding information for Australian, British Admiralty Charts and Hydrographic Publications

INSTRUCTIONS:

1.	Mariners are requested to notify the Hydrographer, Locked Bag 8801 Wollongong, NSW 2500 (Fax 02-4223-6599), when new or suspected dangers to navigation are discovered, changes observed in aids to navigation, or corrections to publications are seen to be necessary. The Mariner's Handbook (NP 100) Chapter 8 gives general instructions. The provisions of international and national laws should be complied with when forwarding such reports.
2.	This form and its instructions have been designed to help both the sender and the recipient. It should be used, or followed closely, whenever possible. Copies of this Form may be obtained from the Hydrographic Office, 8 Station Street, Wollongong, NSW 2500, or from principal Chart Agents (see Australian Notice to Mariners No 2 published annually).
3.	When a position is defined by bearings (true or magnetic being specified) more than two should be used in order to provide a check. Distances observed by radar should be quoted. However, when there is a series of fixes along a ship's course, only the method of fixing and the objects used need be indicated. Latitude and longitude should only be used specifically to position the details when they have been fixed by astronomical observations or GPS and a full description of the method and equipment used should be given.
4.	A cutting from the largest scale chart is the best medium for forwarding details, the alterations and additions being shown thereon in red. When requested, a new copy will be sent in replacement of a chart that has been used to forward information, or when extensive observations have involved defacement of the observer's chart. It is preferred to show the amendments on a tracing of the largest scale chart (rather than the chart itself) these should be in red as above, but adequate detail from the chart must be traced in black ink to enable amendments to be fitted correctly.
5.	When soundings are obtained The Mariner's Handbook (NP 100) should be consulted. The echo sounding trace should be marked with times, depths, etc, and forwarded with the report. It is important to state whether the echo sounder is set to register depths below the surface or below the keel; in the latter case the vessel's draught should be given. Time and date should be given in order that corrections for the height of the tide may be made where necessary. The make, name and type of set, together with stylus speed/sound velocity, should also be given.
6.	Modern echo sounders frequently record signals from echoes received back after one or more rotations of the stylus have been completed. Thus with a set whose maximum range is 500 m, an echo recorded at 50 m may be from depths of 50 m, 550 m or even 1050 m. Soundings recorded beyond the set's nominal range can usually be recognised by the following: the trace being weaker than normal or the depth recorded, the trace passing through the transmission line, the feathery nature of the trace. As a check that apparently shoal soundings are not due to echoes received beyond the set's nominal range, soundings should be continued until reasonable agreement with charted soundings is reached. However, soundings received after one or more rotations of the stylus can still be useful and should be submitted if they show significant differences from charted depths.
7.	Reports which cannot be confirmed or are lacking in certain details should not be withheld. Shortcomings should be stressed and any firm expectation of being able to check the information on a succeeding voyage should be mentioned.
8.	Reports of shoal sounding, uncharted dangers and navigational aids out of order should, at the mariner's discretion, also be made by radio to the nearest coast radio station. The draught of modern tankers is such that any uncharted depth under 30 metres or 15 fathoms may be of sufficient importance to justify a radio message.
9.	Port Information should be forwarded on Form AH 102a together with Form AH 102. Form AH 102a lists the information required for Admiralty Sailing Directions and should be used as an aid memoire. Where there is insufficient space on the form an additional sheet should be used.
	Note: An acknowledgment of receipt will be published and the information then used to the best advantage which may mean immediate action or inclusion in a revision in due course. When a Notice to Mariners is issued the sender's ship or name is quoted as the authority.