NMEA 0183 - GPS, Chartplotter, and VHF

[willingham]

Hi,

I have a dedicated NMEA 0183 GPS unit (Raystar 125) that I’d like to connect to my chartplotter (GPSMAP 942XS) and my VHF radio (VHF850).

This base case seems simple enough, but I’d also like to connect the VHF output to the chartplotter to display DSC calls.

If I connect the GPS -> VHF -> Chartplotter, will the VHF pass along the GPS messages so the chartplotter can see them?

If not, is there another way to configure this without getting a multiplexer?

 

[tiltrider1]

You will need to look at your manuals. I doubt your VHF has the capability to listen to 0183 and then rebroadcast. However, many chartplotters have the capability to receive multiple 0183 inputs.

 

[willingham]

Unfortunately I don’t beleive the chartplotter supports multiple inputs based on this.

 

[Iggy]

You would need to go with a NMEA 0183 Multiplexer to do what you want to do. Cost is about $150 https://www.yachtd.com/products/multiplexer.html

You may want to look at a NMEA2k and you may have to upgrade your VHF with NMEA2k port. It may cost more but a simpler install. Also, giving you the ability of adding more NMEA2k devices.

 

[twistedtree]

A lot of VHFs do repeat incoming GPS sentences on their output. I just don't know about your particular model. You can take a look at the manual for the VHF. They usually list transmit sentences, and if there are gps sentences included, it's a pretty good bet that it will work. Just keep in mind that your Chart plotter will only receive the GPS info if the VHF is turned on. That may be an issue if, for example, you want to leave the chart plotter on as an anchor alarm, but turn the VHF off.

 

[Portage_Bay]

Daisy chaining NMEA0183 signals from device to device has some pitfalls. In addition to turning off a unit as Twistedtree mentions the failure of a device will stop traffic downstream.

Back in the day when 0183 ruled the marine date world I used mutiplexers by NoLand Engineering. I found them to be robust and reliable. The only problems I had were dirty power supply. I haven't kept up with their current product line because I don't need them anymore. But one important feature for me at the time was they had was the ability to feed the output from one multiplexer to the input of the next thereby doubling minus 1 the capacity of a single multiplexer if needed.

If you want/need to mix 0183 with NMEA2000 that will take a different device.