I will take a bite. Marine electronics
are various devices connected via networking protocols. If you want to have a solid installation, I suggest you pay attention to the following:
1. Main devices, chartplotter, radio
need to have solid and appropriately sized connections to power (typically 12V, positive and negative).
2. Most older Garmin
devices interconnect via plain simple serial
interface which is called nmea 0183
in the boating
world. Garmin serial
connections connect the negative to ground. In this case you need to run only one wire for the positive serial signal between the devices. Other serial devices use differential signalling, called RS485. Do not worry about that for now. The trick with serial devices is that the signal goes only one way, there is a talker and a listener. Typically, your GPS
is a talker and sends its data to the chart plotter and the VHF radio
. You can have multiple devices listening to the talker. Then you take the AIS
signal from the radio output port (typically called nmea
out) and feed it back to the chart plotter. You need to make sure that the chartplotter and the radio connect at the same speed or baud. For AIS this is 38400 but sometimes it could be 4800.
3. Most older Raymarine
devices connect through a protocol called Seatalk
. This again is a serial interface and is bidirectional. You have a red wire for 12V, yellow for the positive serial signal and ground. You can connect many Raymarine devices with just these three wires and they will work
fine. However, AIS does not travel on top of Seatalk
which is limited to 4800 baud.
All serial connections are very low current
, so you can splice the wires anyway you want, the signal is very robust.
It is incredibly difficult to interconnect Seatalk and nmea 0183
instruments. They just do not get along. If you get an ST60 wind
instrument, there will be five wires going from the sensor to the ST60 display. You will not be able to display wind information on the Garmin chartplotter unless you have another Raymarine chartplotter on the system. Vendor lock.
3. A third protocol is called nmea 2000
. It deserves a separate email
4. Sometimes vendors use Ethernet for radar
, sonar and weather
Let us know if you have specific questions.