Glad the blogs have been helpful.
I got rid of the AC12. As best I could tell, the problems were interactions between the AC12/48, AP24/28, FU80s, and the NSO EVO. On my last boat
I had an AC42 with AP24 heads and it worked just fine. The only thing different on my current boat
was the NSO EVO and FU80s. And the issues all involved those other devices as part of the AP problems.
And yes, the difference between the AC12 and 42 is the current
drive capability. They also say that you can only use the AC12 with solenoid controlled pumps. I'm not sure why the AC42 wouldn't work
too, but they say not to use it.
I don't think I've ever seen PGN 130577 on a network. Simrad lists is as an acceptable form of heading input, but they also take 127250 and that's what I've always seen. I checked the RC42 and HS70, Simrad's own heading sensors, and none of them generate 130577. So I wouldn't worry about it.