Maps spinning

[Fishndav]

I have an 1198 HDSi at the console that is networked with ethernet switch to a 360 TM and a Helix 12 Chirp SI at bow. Both units have AS GPS HS antennas.

When running in a good chop, the mapping on the 1198 spins around intermittently. It might do it for a 20 seconds, and then it clears up, then it starts up again a while later. I have selected all other GPS antennas to try and fix, as common sense would say it is a heading sensor problem. Even with the internal antennas (no HS) the problem persists. Any of you experts have a guess as to what is going on? I have not tried reloading the software yet. This did not happen after an update, it started out of the blue.

Thanks

fishndav

[exx1976]

There's one spot on one lake I fish that does that.

I found that it is actually changing from one section of the map to another. Zooming out when driving through that area helps.

In your case that could be the cause, or there could be EMI that is screwing with the compass in the heading sensors (high tension power lines, for instance), or possibly satellite interference.

If you are unable to narrow down a specific location that does it, check both your units. Are they both doing it? If so, the people is likely environmental or location-specific, even if you haven't identified it. If it's only one unit, try swapping the units and run through that spot again. That will help you narrow down if the problem is with the unit, or the location of the graph.

I've also heard that when stators begin to fail they can generate a lot of EMI, but I'm not sure the truth to this. How's your outboard doing?

[bobcoy]

Heading sensors are subject to problems if you are bouncing around. If they are tilted side to side and or front to back the direction they think they are pointed gets confused. You may want to select COG instead of Heading for those conditions. That uses GPS generated course rather than magnetic Heading. Under the chart tab then select chart orientation then set to course up rather than head up when choppy. Bob

[Fishndav]

Thanks for the ideas. I will check this out.