single gps antenna for multiple chartplotters

On my boat, I will have 6 Raymarine units(4 12", 2 7"), a Timezero professional system, and two Garmin units(12").

The Raymarine is for augmented reality and object detection as well as system monitoring (7") units. The Garmin units are the Panoptix 51, and the Timezero is for larger monitors for easier visibility for navigation.

My question, is it possible to have a single GPS antenna providing the data feeds to all the units? Or is there a unit that will plug it into the N2K backbone and all the GPS to feed all units?

My Raymarine AR200 is connected to the backbone and supplies both MFDs GPS data.

I would say, yes. As long as the GPS unit/receiver and all MFD can use a NMEA2k backbone.

Since the GPS is the only talker in this arrangement, it can use nmea 0183 to talk to all instruments that need GPS data.

Don't the Raymarine units (at least) have GPS? If so they are already broadcasting it on the N2K backbone (though you can turn that off in the setup). Probably the other MFDs as well. Your problem is more likely to be too many sources, than lack of one.

Thank you. Any recommendations of a GPS antenna then for this?

Lets back up in this. So none of you MFDs have a GPS receiver built in or attached to them. Yes? You just want one external GPS receiver?

From my experience, anything hanging off the N2k network that is sending data the whole network/backbone should see it. The other question is, is that receiving device setup to receive that data. Some MFDs in its settings, you can pick which sending device to accept and ignore others.

sndog said:

Thank you. Any recommendations of a GPS antenna then for this?

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Iggy said:

Lets back up in this. So none of you MFDs have a GPS receiver built in or attached to them. Yes? You just want one external GPS receiver?

From my experience, anything hanging off the N2k network that is sending data the whole network/backbone should see it. The other question is, is that receiving device setup to receive that data. Some MFDs in its settings, you can pick which sending device to accept and ignore others.

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Depending on where you plan to cruise, it may be worth having 2. As mentioned above, generally you can select in each device, which GPS to use.

When picking a GPS unit, one of the considerations is how many times per second it takes and transmitts another position on the NEMA 2000 network. The more transmissions per second, the smoother your positioning is on the chart plotter and the faster it will show changes in your boats heading.

I think currently there are 9 devices that take GPS data off the NEMA 2000 network. Not bad for one unit.

Ted

sndog said:

My question, is it possible to have a single GPS antenna providing the data feeds to all the units? Or is there a unit that will plug it into the N2K backbone and all the GPS to feed all units?

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Yes.

You may already have that, if at least one of your MFDs has a built-in GPS and if everything is already networked together.

We foound an external GPS to be noticeably more accurate that an internal GPS in a shaded MFD, though.

Ours happens to be the external mushroom GPS that came with our AIS but probably everybody makes one.

You have to enter the menu/setup system on each dependent unit to select whatever GPS source you want from among those on your network.

-Chris

Sounds like this is largely a new setup? If so, I would definitely get a satellite compass which is a high precision GPS and compass in one unit. Both parts are better than the stand-alone alternatives, and the cost is around the same as the two stand-alone devices. Around $1200 seems to be the current cost, and the data can be used by all your devices, assuming connected and configured correctly.

The builtin GPS in our Axiom MFD is set back further into the unit. So it doesn’t reliably pick up the satellite signal. I added an AR200 to the network and it shows up on both our MFDs.

I want to make sure to have a strong GPS signal. As my boat is steal, and above the helm is a stell deck, followed by a subframe, then solar panels. So, I do not want to have any type of GPS issue, hence my looking at putting an external antenna onto my antenna mast, so that it has a completely clear and free view of the sky.

sndog said:

I want to make sure to have a strong GPS signal. As my boat is steal, and above the helm is a stell deck, followed by a subframe, then solar panels. So, I do not want to have any type of GPS issue, hence my looking at putting an external antenna onto my antenna mast, so that it has a completely clear and free view of the sky.

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Smart move. Once the antenna receives the signal and the microprocessor converts it to NEMA 2000, the signal travels through shielded cable through out the network.

In addition to a clear view of the sky, it's also important to follow directions on proximity to things like radar. It's all covered in the installation manual, but many people seem to not pay attention to optimal installation practices.

Ted

twistedtree said:

Sounds like this is largely a new setup? If so, I would definitely get a satellite compass which is a high precision GPS and compass in one unit.

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Strongly agree.

O C Diver said:

Smart move. Once the antenna receives the signal and the microprocessor converts it to NEMA 2000, the signal travels through shielded cable through out the network.

In addition to a clear view of the sky, it's also important to follow directions on proximity to things like radar. It's all covered in the installation manual, but many people seem to not pay attention to optimal installation practices.

Ted

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No way, people don’t follow the directions???

I have three chartplotters and an AIS transponder. The two Garmins run off one GPS antenna, the coastal explorer system runs off a second GPS, and the AIS equipment came with its own GPS antenna (and has a separate vhf antenna). The chartplotters were installed that way by the original owner, who had a thing for redundant systems!

The AIS required its own GPS, not sure why….

Spinner said:

The AIS required its own GPS, not sure why….

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Every AIS I've used has it's own GPS but I never really knew why, so a bit of research. I found conflicting information, no surprise there.

From Jeff Cote at Pacific Yacht Systems Says the AIS needs it's own dedicated GPS.
"An AIS transmitter (not receiver) requiresa GPS signal; not only to determine navigationinformation, but also to time themessages it sends and receives. It will need its own dedicated GPS antenna. Youcannot hook up the GPS signals from your chartplotter or VHF radio, because the timing information will be wrong and itjust won’t work. Also, the GPS data from the AIS antenna is not repeated. You’ll need another GPS antenna if you wantGPS information on other devices, for example the VHF radio for DSC emergency."
https://www.pysystems.ca/resources/tech-talk/the-abcs-of-ais/*

Doug Miller at Miltech Marine says that a dedicated GPS for AIS is no longer necessary. But that seems to be relatively new. The quote is from at December 2022 update to an original September 2011 article.
"One question we get asked a lot when customers are looking to buy an AIS Class B transponder is: "can I use my existing GPS instead of needing to install yet another GPS antenna on my rail"? Up until recently, the answer to this question has been "no - you need to use the internal GPS system in the transponder and connect a compatible GPS antenna in order for the transponder to work correctly". Now we have a different answer!"
https://www.milltechmarine.com/Using-an-external-GPS-with-an-AIS-transponder_b_10.html

It seems the answer is that if your AIS is older than late 2022 it will have it's own GPS.

In the for what it's worth column a long time ago I ran a boat with that had a Furuno FA-100 Class A AIS transciever installed. I was told by the installer at that time a dedicated GPS was a regulatory requirement as was external GPS feed as backup. But, that was a long tome ago and I could have that detail wrong.