Multifunction navigation displays such as the Raymarine C and E Series equipment do so much more than traditional chartplotters.

As well as showing the boat's position on an electronic chart, they can show the presence of all commercial vessels and many leisure boats by interfacing with an AIS receiver. An input from an electronic compass or an autopilot can enable a radar image to be superimposed on that of the plotter. Navtex information can also be displayed on the screen when a suitable receiver is installed. In some parts of the world weather information via satellite can also be viewed.

All this is great news for the boat-owner, but there is one small snag: all this wonderful information tends to be transmitted in different data formats and at different speeds. Boat owners the world-over being independent people, they all have different ideas which systems they need to include, or not, on their vessel. So much so that it is almost impossible for a chartplotter manufacturer to predict what the customer may need.

There is a solution however: by drawing up a plan of which equipment needs to be integrated in the system and allowing a little slack for further additions a suitable NMEA multiplexer can be specified. These 'black boxes' integrate the data streams from the various sources and transmit all the data in an easily-recognisable flow to enable the display to work at its optimum.

Many boaters wish their own notebook computer to talk to their on-board navigation system. No problem, be it via serial port, USB or Bluetooth: there is an interfacing solution available.