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Stand: 29.07.2017

SeaTalk Technical Reference        Revision 3.23

General Information

SeaTalk is a simple interface for networking Raymarine/Autohelm marine equipment so that all devices of a ship can exchange and share their data. SeaTalk is a proprietary solution of Autohelm and not compatible with NMEA or CAN. Unfortunately Raymarine keeps the technical details of SeaTalk secret. To assist users who want to develop hard- or software to connect their devices to the SeaTalk bus these pages uncover some of the mysteries. Part 3 adds hints how to interface SeaTalk with a PC. The information is unsupported by Raymarine and was found by watching the bits travelling on the bus. Therefore the description is incomplete inaccurate and may even be wrong. Corrections and contributions are welcome.


The technical description of the SeaTalk protocol is divided into three parts:
  1. Part 1: How SeaTalk works
    1. Hardware-Interface describes the function of the three SeaTalk wires
    2. Serial Data Transmission describes the parameters of the asynchron serial port
    3. Composition of Messages describes the structure of datagrams
    4. Collision Management describes the arbitration between simultaneous talkers
    5. Data Coding describes common rules for coding numerical values
  2. Part 2: Recognized Datagrams describes the SeaTalk messages and their meaning
  3. Part 3: Processing SeaTalk Data with a PC
    1. Circuit example for an unidirectional SeaTalk => PC interface
    2. Circuit example for a bidrectonal SeaTalk <=> PC interface
    3. Simple SeaTalk monitoring utility for download
    4. SeaTrack: VisualBasic software for trip documentation
    5. SeaSigma: A small SeaTalk command generator for download

Revision History:

Rev 3.23: [July 2017] Commands 85 and 89 corrected thx Mindert Sprang and Hans Almquist
Rev 3.22: [May 2014] Command 53 corrected thx John Rhind and Meindert Sprang
Rev 3.21: [March 2011] Time coding in command 54 clarified thx  Tim Thornton
Rev 3.20: [January 2011] Some observations with Raystar 120 GPS included thx Tim Thornton
Rev 3.19: [August 2010]  Command  A2 revised thx Frank Wallenwein
Rev 3.18: [March 2009]  Several commands edited and new commands 05 and 68 added thx Frank Wallenwein
Rev 3.17: [February 2009] Command A4 added thx  Tord Lindner
Rev 3.16: [October 2008] Commands 65, 66, A8 and AB added thx Ray Holland
Rev 3.15: [June 2006]  Command 61 added thx Ian Molesworth
Rev 3.14: [January 2006] Minor changes to commands  26, 01 and  6C thx  Ian Molesworth
Rev 3.13: [December 2005]  Additional bits found in command 26 by Pim Snoeks


Many thanks to

Knut Wiren, Finland
Mikael Wahlgren, Sweden (developed a PIC-based SeaTalk remote control)
Reiner Patommel, Danmark
Arnold de Maa, Holland
Wouter van Ooijen, Netherlands (developed a PIC-based SeaTalk protocol converter)
Jürgen Saniter, Germany (developed a SX-28 based SeaTalk remote control)
Harald Sammer, Scotland
Ales Janhar, Slovenija (developed the SeaSigma utility)
Jon Fick, USA (developed a PIC-based SeaTalk remote control)
Frank Wallenwein, Germany (NMEA <=> SeaTalk Bridge and several boat electronics projects)
Dave Martin, Great Britain
Horacio Martinez del Pezzo, Argentinia (developed an intelligent SeaTalk / NMEA multiplexer)
Pit Förster and Jochen Buttkereit, Germany (supplier of third party SeaTalk equipment for instance Brookhouse interfaces)
Louis Zammit Mangion, Malta (developed a PIC-based SeaTalk remote control)
Meindert Sprang, Netherlands (develops and manufactures NMEA/SeaTalk/Bluetooth/RS232-multiplexers)
Dennis Hambleton, Australia
Fernando MAS CADIZ, Spain
Ray Holland, Australia (developed a WakeUp Marine Alarm box)
Tord Lindner, Sweden and
Tim Thornton, United Kingdom
(TeamSurv project for navigational data logging and Smartcom Software Ltd.)

who contributed valueable information for this page.

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