[CA] [CA11] ST60+, seatalk1, seatalk NG, ray55e, A70D and ST2000+

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Hi Chuck,
Thanks for another very helpful response.

Regarding your response to question 6b, as follows, “consider interfacing the autopilot's NMEA 0183 input port to the NMEA 0183 output port of the MFD (NMEA 0183 output may be paralleled). The MFD will not transmit heading data to the autopilot.”

This is a much neater solution than my idea of using a switch to change heading sources. Thanks for the suggestion.

Q1. Am I correct in assuming I can have the autopilot and third party compass both permanently connected?

Q1. I assume that the autopilot still uses it’s own compass but the MFD and other instruments use the third party compass’ heading data in this arrangement, hence the need for both compasses to be closely aligned?

It seems to me that the only time heading discrepancy might be an issue is when using track mode on the autopilot.
Q2A. If there was any discrepancy between the two heading sources the autopilot (when in track mode) would see the discrepancy as current or leeway and compensate accordingly. Initially the boat might be off course by the amount of the discrepancy but it would soon return to the track. True?
Q2B. Are there any other problems you foresee regarding heading discrepancies?

In summary, could I connect up as follows:
- Autpilot NMEA IN, pin 6 (+) and pin 5 (-) connected to MFD NMEA OUT Orange/Yellow (+) and Orange/Brown (-).
Provides wind data from ST1 instruments, via ST1/STNG Converter, to the MFD. Then the wind and navigation data go by NMEA to the autopilot.
Autopilot heading data is not output to the system on the MFD NMEA OUT connection. And compass heading data is not sent from the MFD to the autopilot.
- Third Party compass NMEA OUT connected to MFD NMEA IN Orange/White (+), Orange/Green (-) [or to ground depending on compass comm type].
Provides Heading data to the MFD and hence via STNG/ST1 converter to the ST1 instruments (for heading display and set/drift and true wind calculations etc.).
- Autopilot Seatalk 1 (pins 2 and 4) disconnected (to exclude autopilot heading data from the ST1 bus). Autopilot has only power and NMEA IN connected.
- the MFD’s other NMEA IN/OUT ports (white/green and yellow/brown) will remain connected to the Ray55e VHF (so there’s no need to parallel the NMEA connections).

Does that sound ok?

Thanks again for the great support and good ideas.
Regards
Dave