"Nav Data Not Present"



I have a Navnet 10 with a 500 Autopilot. I was using the boat each day in the keys and the Nav function worked fine.

At some point, day 4 in the keys, the Autopilot started giving the "Nav data not present" error message. It still works on the Auto setting but not on Nav.

I am reasonably sure nothing was changed in the settings. All the connections seem to be o.k.

Any thoughts on what the problem is and better yet, how to resolve it?

Assuming your wiring is still good and no one changed your output settings, it is doubtful the port quit working. I would guess someone switched the NAV input on the pilot. Try holding the NAV button for 3 to 5 seconds and switch your NAV source and then try a goto and NAV.
Thanks. My manual says hold course control knob 5 secs to change ports. That did not work. Neither did holding the Nav button 5 secs. However, I was able to use the menu key and get to parameters. I was then able to change the port. The choces are Port 1, Port 2, and Both. Mine was on Port 1. Change to Port 2 was not successful. But, when I selected the Both option, Nav data appeared on the Autopilot. Success!

Thanks for putting me on the right track. I am befuddled by why the Both option works when neither Port option works but I am happy it works.

It sounds like you have some really old software in pilot, or there is a NMEA level issue going on. For example if you take RS232 level NMEA into an RS422 input port, it can work but only about 90% of the time. (not recommended) It is best to use a proper level converter or wire into the proper level port. Glad it started working for you.
The unit is a 2004, so I am rooting for the old software theory--as opposed to some level issue I don't understand. I got the boat a couple years ago. There were no problems until now.

I'll use it and hope it keeps working. If not, I will cry for help.

Thanks again.