Well, the plot thickens for me. I took the boat out a couple days ago to test the change in settings on the Lowrance. However, the Xi5 appears to have experienced a failure in the GPS module (per MG support). The GPS lock blue indicator light comes on about 30 seconds after the Xi5 is powered on, then the light goes out, and stays out, after about 3 minutes. The only way to get the GPS lock light to come on at all is by powering off the Xi5 and powering it back on, but the GPS indicator light goes out every time. Definitely something wrong, and maybe it was failing all along and was causing the errors in navigation.
So the Xi5 is heading to an authorized service shop, and I learned there are no repair shops in Washington (my state), none in Oregon, and none in northern Idaho. The closest shop is in Montana, over 360 miles one way from me. Thus the Xi5 has to be shipped, which is not going to be cheap. I haven’t heard back from MG support, but they better reimburse me the shipping charge – it’s not like we live on another planet. With the difficulty in finding a repair shop, coupled with the problems I’ve been having with the Xi5 and its integration with the Lowrance, I think I blew it by not buying a Minn Kota.