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Furuno “Loss of GPS”/DOP Error alarm and AIS help


tony wells
 
Edited

Hi All

Grateful for your thoughts:

1. My 2008 A54 #102 has the Furuno GPS Navigator GP-150. It’s recently started sounding an intermittent No GPS alarm and, more frequently, a DOP Error alarm. It self tests fine. In Alarm settings I’ve selected OFF for the GPS alarm. I have selected RAIM OFF. I have tried to smooth the fixes by selecting a long interval. I’ve selected 3D/2D instead of 2D because the DOP threshold is (counter-intuitively?) less sensitive. But No GPS or DOP Error alarms still sound when underway. Sometimes several times in a few minutes and then, as I say, after an interval of over 30 minutes for just one time. In the port currently, 5-8 satellites are showing. 

I’m replacing all the Nav this winter but would like the equipment to work on passage tomorrow from Kefalonia to Malta via Sicily (320Nm). If I turn the GPS Navigator off (and use papercharts and iPad) then the Furuno auto pilot No Speed alarm sounds (despite me switching off that Alarm on the Autopilot!). 

One thought (credit Bill Rouse, thanks) is UV damage to the GPS antenna (in presumably usual location starboard side cockpit under hard Bimini roof). Any other thoughts / straightforward Autopilot workarounds please? 

2. AIS. I have Furuno Navnet vx2 at the Nav station. There does not appear to be an AIS option despite the boat having a receiver. It seems AIS vessels were only displayed on the helm repeater (not the Nav station plotter where there is no AIS option) but this plotter has ‘frozen’ and does not show current position regardless of repeated reconnection. I have tried Corrosion X in the terminals. Any thoughts on why this may not be working or can anyone tell me how to display AIS at the Nav station plotter please? 

UPDATE: Corrosion X has now solved the problem. Nav AIS working too. Still grateful for any help on Point 1 re GPS/DOP Error alarms please 



Thanks very much!

Tony Wells
A54 #102 Argostoli,
Kefalonia, Greece


 

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On Thu, Sep 19, 2019 at 11:30 AM tony wells via Groups.Io <tony.wells=me.com@groups.io> wrote:

[Edited Message Follows]

Hi All

Grateful for your thoughts:

1. My 2008 A54 #102 has the Furuno GPS Navigator GP-150. It’s recently started sounding an intermittent No GPS alarm and, more frequently, a DOP Error alarm. It self tests fine. In Alarm settings I’ve selected OFF for the GPS alarm. I have selected RAIM OFF. I have tried to smooth the fixes by selecting a long interval. I’ve selected 3D/2D instead of 2D because the DOP threshold is (counter-intuitively?) less sensitive. But No GPS or DOP Error alarms still sound when underway. Sometimes several times in a few minutes and then, as I say, after an interval of over 30 minutes for just one time. In the port currently, 5-8 satellites are showing. 

I’m replacing all the Nav this winter but would like the equipment to work on passage tomorrow from Kefalonia to Malta via Sicily (320Nm). If I turn the GPS Navigator off (and use papercharts and iPad) then the Furuno auto pilot No Speed alarm sounds (despite me switching off that Alarm on the Autopilot!). 

One thought (credit Bill Rouse, thanks) is UV damage to the GPS antenna (in presumably usual location starboard side cockpit under hard Bimini roof). Any other thoughts / straightforward Autopilot workarounds please? 

2. AIS. I have Furuno Navnet vx2 at the Nav station. There does not appear to be an AIS option despite the boat having a receiver. It seems AIS vessels were only displayed on the helm repeater (not the Nav station plotter where there is no AIS option) but this plotter has ‘frozen’ and does not show current position regardless of repeated reconnection. I have tried Corrosion X in the terminals. Any thoughts on why this may not be working or can anyone tell me how to display AIS at the Nav station plotter please? 

UPDATE: Corrosion X has now solved the problem. Nav AIS working too. Still grateful for any help on Point 1 re GPS/DOP Error alarms please 



Thanks very much!

Tony Wells
A54 #102 Argostoli,
Kefalonia, Greece


Dean Gillies
 

Hi Tony,
The Navnet3D system has a failover action with GPS that I’ve observed, which may be relevant to your problem.

Typically there is more than one GPS data source available in a system. In my case it was the FA50 AIS and the GP150. The source to be used is selected as you step through the system installation process. In my case it was selected to be the GP150.
If during normal operation, the source of GPS fails then the system automatically changes to the other GPS source. In my case, the GP150 failed and the system started to use the FA50 AIS as the source of GPS. I knew nothing about the change, as the system just did it automatically.
It took some time before I noticed the GP150 had actually failed and was not supplying GPS data anymore.

This does not help with the question of why your GP150 is faulty, but may help in your understanding of what has happened in your system.

Furuno would not repair my GP150 so I bought a a couple of inexpensive GPS antennas with NMEA outputs and located them behind the instrument table. They are now my (dual redundant) primary source of GPS for the system.

Good luck!
Dean
SY Stella
A54-154


tony wells
 

Thanks Dean

That’s helpful in developing my understanding, as you say.

In fact it turned out the AIS issue was compounded by an intermittent power drop out with the router which we identified on passage to Sicily.

The “No GPS” and DOP alarms are still sounding intermittently. I can’t see how there’s any correlation but it seems more prevalent when closer to land?! There were no alarms when 100Nm offshore!

Thanks again,

Tony
Balthazar A54 #102, Syracuse, Sicily

On 20 Sep 2019, at 13:33, SY STELLA <stella@...> wrote:

Hi Tony,
The Navnet3D system has a failover action with GPS that I’ve observed, which may be relevant to your problem.

Typically there is more than one GPS data source available in a system. In my case it was the FA50 AIS and the GP150. The source to be used is selected as you step through the system installation process. In my case it was selected to be the GP150.
If during normal operation, the source of GPS fails then the system automatically changes to the other GPS source. In my case, the GP150 failed and the system started to use the FA50 AIS as the source of GPS. I knew nothing about the change, as the system just did it automatically.
It took some time before I noticed the GP150 had actually failed and was not supplying GPS data anymore.

This does not help with the question of why your GP150 is faulty, but may help in your understanding of what has happened in your system.

Furuno would not repair my GP150 so I bought a a couple of inexpensive GPS antennas with NMEA outputs and located them behind the instrument table. They are now my (dual redundant) primary source of GPS for the system.

Good luck!
Dean
SY Stella
A54-154




Scott SV Tengah
 

We had a similar problem with our GP-150. The errors showed up right as we left Las Palmas to cross the pond!

I called Furuno and they suggested that we check all of the connections as the head unit itself is not likely to be the problem given our symptoms. 


--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com