Did you know that some VHF marine equipment has an ‘International’/‘USA’ control setting? This is provided by manufacturers to permit communications with stations in the USA that don’t conform to the International VHF channel plan.
It’s important that you keep this control in the International (INT’L or INT) position at all times—unless you’re operating your radio within US coastal waters (some manufacturers of VHF marine radios supplied to Australian operators may substitute ‘AUS’ for ‘International’).
If you’re operating your radio within Australian territorial waters and this control is set to USA, you may not receive transmissions on some channels. This is because the channel configuration in the US differs from the International channels—for example, some channels that are duplex in Australia are simplex channels in the USA.
You may also experience difficulty accessing repeaters stations on channels 21, 22, 80, 81 and 82 for the same reasons. This means that your signal may not be heard in certain areas.
For your peace of mind, check this control and make sure you’re set to International.
More information is available in the Marine Radio Operator’s Handbook and the Australian Global Maritime Distress and Safety System (GMDSS) Handbook 2013.