[CA] Seatalk to Garmin 740s?

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum skipmac,

Contrary to your statement, the ST40 Instruments were indeed designed to be installed and operated in direct exposure to the marine environment. These instruments were designed to be waterproof to the IPX5 Standard. Should an ST40 Instrument have experienced a water intrusion failure and should one be seeking to install it in a location which will be exposed to weather, then it would be recommended that the instrument be serviced by Raymarine’s Product Repair Center or replaced with an i40 Instrument.

Q1. From photos it appears that converter comes with a cable that plugs directly into the 3-pin Seatalk port on the back of the ST40 bidata display? The transducers will stay connected to the ST40 display as before.
A1. Correct. The supplied SeaTalk to SeaTalkng Cable will be used to interface the SeaTalk socket (yellow) of the SeaTalk to SeaTalkng Converter to the SeaTalk socket of the instrument or a D244 Junction Block within the vessel's SeaTalk bus.

Q2. Connect the ST-STng converter to a T on my NMEA backbone which I think will take an adapter cable? Which cable and part number?
A2. The ST-STng Converter is designed to be installed a NMEA 2000 backbone component, not as a spur component. Accordingly, the ST-STng Converter will be interfaced to the currently installed SeaTalkng backbone via one of the following methods:
- at the end of the backbone: SeaTalkng Blanking Plugs (black) will be installed within the ST-STng Converter's two spur sockets (white). A SeaTalkng Termination Plug (blue) will be installed with one of the backbone sockets (blue) of the ST-STng Converter. The NMEA 2000 Terminator will be removed from the end node of the existing NMEA 2000 backbone to which the ST-STng Converter will be interfaced. An appropriate length SeaTalkng Backbone Cable will be connected to between one of the ST-STng Converter's backbone sockets (blue) and a backbone socket within the currently installed NMEA 2000 backbone. Please click here to view a FAQ addressing how the SeaTalkng backbone cable may be modified/adapted to be mated to the backbone socket of a NMEA 2000 backbone which has been constructed from third party NMEA 2000 networking components.
- within the middle of the backbone: SeaTalkng Blanking Plugs (black) will be installed within the ST-STng Converter's two spur sockets (white). A SeaTalkng Termination Plug (blue) will be installed with one of the backbone sockets (blue) of the ST-STng Converter. An appropriate length SeaTalkng Backbone Cable will be connected to between each of the ST-STng Converter's backbone sockets (blue) and a backbone socket within the currently installed NMEA 2000 backbone. Please click here to view a FAQ addressing how the SeaTalkng backbone cable may be modified/adapted to be mated to the backbone socket of a NMEA 2000 backbone which has been constructed from third party NMEA 2000 networking components.

Q3. Is that all or will I need any additional cable, converter, adapter or black box?
A3. See the response to Q2.

Q4. The converter has 5 ports and includes two cables (power and ST) and two plugs, two terminators. Do all the ports have to be filled with cables, plugs or terminators? Assume the manual will cover this?
A4. See the response to Q2. Should the currently installed NMEA 2000 backbone be powered, then the supplied SeaTalkng Power Cable will not be used, as the ST-STng Converter will instead receive power from the currently installed backbone when installed as specified within the response to Q2.