GPS Source

I have two Pilothouse Garmin 7612 units and currently they are using their own GPS source. This causes slight speed differences, AIS separate warnings etc. I was thinking about using a single source for data. Am I missing something? Assuming I can select a master source for GPS?

I have Raymarine chartplotters and I have one designated as Master and the other designated Slave, I know, not PC but it's their terminology. Can you do that with Garmin?

I think (but not am electronics guru) that your NMEA network should be able to handle one source to multiple units for you.

I can select a master GPS source, yes. I think I’ll try that. Thanks.

jimdavi said:

I can select a master GPS source, yes. I think I’ll try that. Thanks.

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I have a similar setup to you. I have the plotter on the Fly bridge act as the source for GPS for all the NMEA2k components. By default it is set to auto which allows it to bounce around.

I have 3 separate GPS antennas. One is an older Raymarine antenna that supports a Raymarine GPS head and the Raymarine chartplotter. I also use Coastal Explorer on a laptop that can select which of the 3 GPS sources I want it to use with automatic switching to another unit should the first priority go down. The other GPS sources are a GPS puck and an antenna that signals my Vesper XB8000 AIS. Currently on CE my priority is the Vesper unit. There are small difference occasionally between the older Raymarine and the new Vesper, but not enough that it worries me.
As backup, I also run 2 separate IPads with Navionics and each IPad has it's own built in GPS, so in essence, I have 5 GPS antennas (signal sources). Now, let's make sure the entire system does not go down

if all your instrumentation is utilizing the MMEA2k, then yes you can select one of the units as a master (preferably the one up on the Fly Bridge if you have one).
Good luck,

Hmmmm... I guess I'm wondering about the comment that you are reading different SOG readings. On my Simrad (3 mfd's) equipment all read pretty much exactly the same SOG even though they are using their own GPS's directly. Understand that the averaging algorithm of each probably adjusts for any instantaneous variations but still I have NO detectable differences. So maybe an investigation into why these differences are occurring may lead you to a resolution of your difficulties?

I agree with rbcooper. When underway, I am often using 4 different GPS sources at once and my SOG never varies more than about 0.1 knots between units. To me, not enough to worry about, especially at 7-8 knots.

I have 2 Garmin 740's connected via nmea2000 and they share 1 gps. If your 7612's are connected, then you should be able to designate 1 as master.