If you own or use a Marine VHF Radio make sure you know the procedures for radio use 
National and international systems exist to provide prompt and effective search and rescue assistance to ships in distress. By complying with the correct radio protocols and procedures, ship station operators can ensure that these systems continue to work effectively for the benefit of all users.

Calling a coast station or ship station on channel 16 
Keep it clear—call and switch.  Call on channel 16, then switch to an appropriate working channel that will keep channel 16 clear for someone else to use.

Marine Rescue Broken Bay monitor a repeater station Channel 21 located on the Central Coast. These Channels give better coverage when well offshore and skippers are encouraged to use these repeater Channels

Repeater stations along the NSW coast

Alternatively, before you leave the wharf, arrange a sked on an appropriate working channel. When calling and working with other vessels—use channels 72, 73 or 77. When calling and working with a coast station—use channel 73.

Note: Position reports can be transmitted via DSC to Marine Rescue Broken Bay VMR213

The following link will assist you in understanding the use of Digital Selective Calling 

Further information on the above items can be obtained from the following web site

Radio Operation Documentation and videos.