[DG] [DG11] 400G AST, ST6001+ auto pilot system malfunctioning

[nscott54]

My Island Packet 420, displacement 38000 lbs, has 2004 vintage Raymarine electronics, including an RL80C plotter, 400G AST course computer, ST6001+ A/P control head and a Type 2 long linear drive.

Over the past couple of years the auto pilot system has been playing up intermittently, but not consistently. Initially, about 2 years back, the system would jump from auto to standby with no alarm. It still does this, but now, when in Track mode, the auto pilot will, on occasion, start wandering off course. The frequency of these symptoms can vary from several times in a day to maybe only once every 2 or 3 days, both of these during long, multi-day passages.

I have checked power supply connections and for adequate voltage - these appeared to be OK.

It is probably time to upgrade the autopilot side of my electronics.
I think that the appropriate new equipment would include an EV-1 course computer, a P70S control head and an ACU-400 actuator control unit.

I have a couple of questions/requests for clarification:

1) would this new equipment interface with the RL80C?
If so, can the new equipment be hooked directly into SeaTalk, or would they need to go through a Seattle/SeaTalkNG converter?

2) My read of the 2016 Forum post entitled "Replacement for a ST6xxx, ST7xxx, or ST8xxx AutoPilot control head" is that a current generation Control Head could work with some earlier generation Course Computers. Does this work in reverse? That is, would an EV-1 be compatible with an ST60001+?

3)If the answer to 2) is yes, if I purchase an EV-1, is the ACU-400 also required, or can the EV-1 operate off my existing ACU (if I indeed have one)?

thank you for your help with the questions.

Neil Scott