SeaTalk is a proprietary protocol developed by Raymarine®. This protocol is used for communication between Raymarine navigation instruments like the ST40, ST50 and ST60 series.
SeaTalk is often referred to as SeaTalk1 and should not be be confused with SeaTalkNG. Seatalk is the "old" protocol/network that uses the well known 3 wire cables (red, yellow and shield) whereas SeaTalkNG is Raymarines flavour of NMEA 2000 with a different connector.
All MiniPlex-3 multiplexers are capable of transmitting data onto the SeaTalk1 bus. From firmware version 1.13.0 onwards, the MiniPlex-3 converts SeaTalk1 data into NMEA 0183 and NMEA 2000 vice versa: from NMEA 0183 and NMEA 2000 into SeaTalk1.
The following table lists the SeaTalk1 datagrams by their number and function and wether they are transmitted (TX) and/or received (RX).
| Datagram | Function | TX | RX |
| 00 | Depth | • | • |
| 10,11 | Wind angle and speed | • | • |
| 20,26 | Speed through water | • | • |
| 21,22,25 | Log (trip and total) | • | • |
| 23,27 | Water temperature | • | • |
| 50,51,52,53,54,56,58 | GPS | • | • |
| 84,9C | Rudder angle | • | |
| 89,99 | Magnetic heading and variation | • | • |