Further to what Ramona said. A new feature of the newer Trek Transponders (4G boat alarm/monitor) is that can output NMEA-0183 nav data from its GPS every one second wirelessly (by Bluetooth) for use by OpenCPN. If you plug a Bluetooth wireless dongle into a PC/Laptop/Tablet as Ramona mentioned you can then use OpenCPN anywhere on your boat. ie. At the helm or below if its raining etc. OpenCPN is free, and OpenCPN charts for East Coast Australia are about $60.
opencpn.org/ This was brought about by popular request, ie many others don't like being ripped off or navigating in the rain!