Ships GPS selector switch ?

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Boo2

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Hi,

Sunrunner has 3 possible sources of NMEA GPS data :

  1. Handheld GPS
  2. Handheld VHF
  3. Chartplotter
It would be nice if there were a way to select which of these was used as the ship's GPS. Something like a 3 pole (NMEA+, NMEA-, Gnd) 4 way (3 I/P, 1 O/P) waterproof ('cos on a boat) rotary selector switch would be ideal. But I'm open to other ideas too...

Any suggestions ?

Thanks,

Boo2
 
What do you mean by "ship's" GPS? My slightly eclectic instrument fit on Ariam has 4 GPS receivers feeding various different things. And does it necessarily make sense to redirect the NMEA output of whatever's on the other side of the switch between these three devices? What is (say) the handheld VHF going to make of it?

EDIT: Just realised you weren't talking about NMEA output; I jumped to the wrong conclusion from the mention of two NMEA conductors and a ground. But why both NMEA - and Gnd?

Nevertheless, RS or Farnell will let you filter their catalogue of switches by things like IP rating and number of poles.

Pete
 
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Navmon PC?

http://www.navmonpc.com/downloads.html

A PC based system that is user configured to allow you to choose which gps source and where your NMEA is distributed.
Quite a powerful tool but not a simple switch and needs a PC to manage it.

Why the need redundancy?

Navmon Pc allows you to specify which source takes priority and which one takes over should the primary fail etc...
 
Just to elaborate on my four GPS receivers...

1: The sailing instruments and main plotter. Raymarine GPS mushroom connected to Seatalk, with ST60 instruments, a C70 radar/plotter, Raymarine autopilot. All the typical light grey kit state of the art circa 2005 :). Everything except the plotter is on one panel switch, the plotter is on another. Turning on the plotter without the instruments doesn't make much sense because it will have no position or heading data to work with, but vice versa is perfectly fine and common when pottering around my local area. Seatalk data (especially log distance as I write this next to fixes along with the time) is also displayed on an ICS Navtex at the chart table via a Seatalk -> NMEA bridge.

2: BR355 GPS "puck" supplying the DSC VHF and the AIS display, all three of which are on one switch so come on and off together and independently of anything else. An additional NMEA link carries the AIS data from the VHF to the display.

3: Garmin GPS128, connected to a Yeoman plotter and a basic cockpit repeater. Again on its own switch so from the electrics panel onwards it's a completely independent system. NMEA output from the GPS to the Yeoman and the repeater, and the Yeoman output goes to the GPS in order to create waypoints by "clicking" on the physical chart.

4: Small Lowrance 4m plotter on the binnacle, for use by the helmsman for the last mile up an unfamiliar harbour and usually turned off most of the time. Self-contained GPS, but takes its power (no data) from the nearby Seatalk bus.

These systems are independent (apart from the batteries) not out of a specific desire for redundancy (though that's a nice bonus) but because they do different things and are used differently, and there's no particular reason to connect them. With NMEA being a point to point system, one needs to consider what data needs to get from which device to which other device, and put the appropriate links in place. A lot of people seem to just come at it with a vague idea of connecting everything to everything else and then unspecified "stuff" will happen.

What other device(s) will be on the other side of your "ship's GPS" switch?

Pete
 
Talulah said:
Chartplotter may have a menu option to turn off the internal GPS and set the plotter to repeater.
Click to expand...

Since he's only talking about using the plotter as a source of position data, not piping data into it from elsewhere, I'm not sure what that has to do with the question at hand :)

Still, it's indicative of the general confusion on the subject. Boo2 - what are you actually trying to do here?

Pete
 
prv said:
Since he's only talking about using the plotter as a source of position data, not piping data into it from elsewhere, I'm not sure what that has to do with the question at hand :)

Still, it's indicative of the general confusion on the subject. Boo2 - what are you actually trying to do here?

Pete
Click to expand...

Also not applicable as he has a C70. I don't think the C70 has an internal GPS so can't be a source of data although it can bridge some Seatalk to NMEA sentences.

(C wide series had internal GPS)

The original question is wrong!
Sunrunner has 3 possible sources of NMEA GPS data :


  1. Handheld GPS
  2. Handheld VHF
  3. Chartplotter


Option 3 should be the Raystar, not the chartplotter.
 
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prv said:
GPS source for what?
Click to expand...
Main VHF + laptop + anything else I ever attach.

I am not saying it is a key requirement but I am wiring up / have just wired up the e7 and the VHF so now would be a good time to do it. And if a waterproof 3 pole, 4 way rotary switch was readily available then it would be rather easy to achieve so no particular reason not to...

Boo2
 
Boo2 said:
And if a waterproof 3 pole, 4 way rotary switch was readily available then it would be rather easy to achieve so no particular reason not to...
Click to expand...

RS or Farnell then, as I said in post #2. Take your pick from hundreds :)

Still don't understand why 3-pole for a one-way NMEA link though.

Pete
 
I have two sources of GPS positional data, a Garmin GPS and Navman Plotter. I used to simply feed the NMEA into the VHF for DSC mayday situations from the plotter. Then one day the plotter went "funny" for an hour, the Garmin still behaving perfectly. Made me think, during that down time on the plotter I had no positional data etc going into the VHF. A simple single pole change over switch to select either the Garmin or chart plotter into the VHF provided a simple instant back up. Minimum cost for a miniature sealed SPCO switch from RS. Only needed to switch the NMEA +.
 
prv said:
RS or Farnell then, as I said in post #2. Take your pick from hundreds :)

Still don't understand why 3-pole for a one-way NMEA link though.

Pete
Click to expand...

He is planning on switching the ground as well as nmea + and -! Silly boy.
 
Only three?

last time i was on my boat we had seven -chartplotter - old chartplotter left in place -3X mobiles-2X tablets

The only gismo that gets (rather than gives) a position is the DSC

Funnily enough they all read the same so i don't feel the need to switch
 
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