[chouliha]

First time poster on this forum. I did a search but could not locate anyone reporting this issue.

We have been using the ipad and iNavX charting for more than a year now. Full time cruisers currently in Western Panama.

We are also running 3 other GPS/ charting programs. OpenCPN, Furuno GPS32 , Furuno radar chart plotter and a Vesper Marine AIS 850. Each of these units provides GPS information.

When underway, COG as displayed in iNavX on the iPad is not in agreement with my other onboard GPS receivers. Carefully watching the OpenCPN program being fed by the Vesper marine 850 AIS and the Furuno chart plotter being fed from a standalone GPS antenna and the Furuno 32 GPS all 3 show the COG if not the same very close (within 1 degree). But the iPad / Inavx is off by up to 15 degrees!!!

In the example sent to iNavx the boatspeed was 4-7 knots. They have been very responsive and I respond to them with all my current settings. But currently there is no solution. Hence my note to the group

The interesting thing is that even though the COG line shows we are way off the course line the boat still appears tracking right on the WP line. The vessel would show staying on the track but the velocity vector would show us steering off course. I could not use this feature as it was incorrect.

iNavx responds: I have not heard of COG being incorrect. iNavX displays exactly what the iPad reports as COG. So if iNavX has COG wrong, every other app would also. COG is computed by taking the bearing from the previous GPS position to the current position. So if HPE: were a high value then it could explain an incorrect COG. (Less than 20 is ok.)

Our ipad HPE is under 20. Is there another setting on the ipad that could be causing a issue?

Has anyone else experienced this problem?

Thanks in advance for suggestions

Chuck
Jacaranda

[GPSNavX]

Are your other iPad navigation apps reporting incorrect COG?

[chouliha]

This is the only Ipad navigation app that I currently have on our ipad.
Chuck

[AlanR]

My COG is unusable, because it changes from GPS fix to fix, and because of the small uncertainties in the position each fix, the COG varies, sometimes even more than the 15 degrees you quote.
My Furuno navigator overcomes this by averaging the course over a selectable period. I usually set this to 60 seconds, but in some sea condition increase it to 120 seconds. I would really like to see this feature on iNavx
Even a pre-set period of one minute would be better, but being able to adjust tie period is the gold standard.