A vessel in distress may display any of the following signals to indicate that they are in distress and require assistance. The obligation of other vessels to assist is absolute.
International Collision Prevention Regulations, 1972
The following signals, used or exhibited either together or separately, indicate distress and need for assistance:
(a) a gun or other explosive signal fired at intervals of about a minute;
The use or exhibition of any of the foregoing signals except for the purpose of indicating distress and need of assistance and the use of other signals which may be confused with any of the above signals is prohibited.
Attention is drawn to the relevant sections of the International Code of Signals, the Merchant Ship Search and Reacue Manual and the following signals
(a) a piece of orange-coloured canvas with either a black square and circle or other appropriate symbol (for identification from the air);
Note: Item 3(a) is the equivalent of a “V Sheet” reqired to be carried by all Australian vessels travelling in open waters.