Upgrade from E120 Classic to C125

[Chuck - Raymarine - Moderator]

Stuart,

Q1. When you refer to the "Seatalk Bus", are you refering to the D244 Junction?
A1. Per the FAQ referenced within my initial response, instruments, autopilot components, GPS sensors, and chartplotters featuring a 1st generation SeaTalk interface which do not additionally feature a SeaTalkng interface (ex. ST40/60 Instrument Displays, ST6001, S2G, Wireless AP Controller, Raystar 125 GPS Sensor, etc.) should be interfaced to one another, in any order, using standard SeaTalk Cables. SeaTalk Cables can be joined using D244 SeaTalk Junction Blocks, splices, marine grade terminal strips, or R55006 SeaTalk Auxiliary Junction Boxes. SeaTalk Cable is available in 15", 1m, 3m, 5m, and 9m lengths. This method of interfacing is referred to as a SeaTalk bus. Should you not be well acquainted with how the equipment has been interfaced onboard your vessel, then you may want to seek the assistance of a Certified Raymarine Installer. The easiest way to disconnect the MFD from the SeaTalk bus would be to unplug the SeaTalk/Alarm Cable from the MFD's SeaTalk/Alarm port.

Q2. to connect the E120 as a spur to the SeaTalkng backbone, would I need another converter, or would the the E120 connect directly to one of the white spur ports on the converter using a Seatalk to SeatalkNG adapter cable?
A2. Raymarine offers a A66061 E-Series Classic to SeaTalkng Adapter Cable to support interfacing an E-Series Classic MFD as a spur to a SeaTalkng backbone.

Q3. As for the auto pilot computer it is a S2G AST. It does not have a gyro connected, only the rudder and fluxgate. Picture attached.
A3. The S2G is a gyro assisted autopilot course computer having an internal gyro mounted to the course computer's processor board.