GPS inconsistent between units?

I was fishing Cutfoot/Winni this weekend and the HDS gen1 on the bow and the HDS gen1 on the dash were quite a bit different showing my GPS location compared to the structure. Both are chipped with Lake Insight maps….a 2013 version and 2014 version. The 2013 version was on the bow and seemed more accurate.

Anyone have any ideas or suggestions as to why they are not showing a consistent position?

I checked the Lowrance website and it looks like the most recent update is from Feb 2012 and both units have been updated with that update….is that right…there haven’t been any updates since 2012 for the gen 1 units?

The odd thing…I bought the units new and there hasn’t been a problem until this year….nothing changed with the boat or chips.
Thanks

Are the units networked?

Yes….they are networked

HDS also has an Auto Select feature, when this is enabled the HDS will choose the antenna with the best
Signal to Noise Ratio (SNR) from the available satellites. Depending on mounting location, view of the
sky, etc.

You should be at the same location if you’re using one antenna.

Possible windshield interference at the console if you’re not using one
antenna.

I have 3 HDS and only use one map chip. Ethernetworked.

I have them networked with the ethernet, but I thought each unit has to have it’s own chip to have the contour lines so they are both chipped.

I have them just running the GPS on the internal antennas so each unit is getting it’s own signal.

The confusing part is they’ve been set up the way they are for a couple years and I haven’t noticed the discrepancy in the past. Both units have an unobstructed view of the sky. The console unit sits with about half the unit above the top of my smoked windshield on my Ranger so there shouldn’t be clear line of sight issues.

They are probably 20-30 yards different so it is pretty significant discrepancy.

Even though they deregulated the signal, there is still some scrambling of the signal. 20 to 30 yards difference between units isn’t that far off. I don’t know for sure if that is what is causing the difference, its just a thought. I have a elite7 at the helm and a x26 on the bow and see a half mph difference between the two units while trolling. Surface temps are sometimes a degree or two different at times, this could be because the bow unit is on the bow mount and is about a foot deeper in the water than the transducer mounted on the transom.