[Fuzzdr]

Thanks to Captain J Clark for his enlightened comments and his interest in my situation. I boat in the fresh waters of Georgian Bay. I wonder if this makes a difference to the RF ground source? I am not sure if my chart plotter was set for North Up mode or not- will check on that. When I first noticed the boat going backwards on the display, I was actually travelling some flavour of east. This continued even after I had turned north and then westward and then north again. Early on I could see short glimpses of land even through the rain and poor visibility. I knew exactly where I was at that point even though I had lost my gps fix and had no working radar.
I think that after that I must have started to travel in circles inadvertently. Eventually our gps fix returned; it showed our position to be far south and west of our intended route! A circle course most probably took us there and it seems simultaneously calibrated the heading sensor of the autopilot which had been in standby mode. After the gps fix returned, everything improved and we were able to reach our destination without incident. Since then we have not had the opportunity to do a sea trial to determine what is working and what is not. That sea trial has top priority now.
Thanks again Captain J Clark. Please feel free to comment further as you see fit.

Fuzzdr