SeaTalk NMEA Bridge & Repeater - Connecting Seatalk und NMEA devices
Datum: Samstag, 06.Mai. @ 12:11:06 CEST
Thema: Boat electronics - Yachtelektronik

This article is about the original SeaTalk NMEA Bridge developed years ago. 
In our current version of the bridge, we have added a lot of new features and functions.
You can find the new SeaTalk Nmea Bridge  HERE
New Bridge

SeaTalk Interface

The SeaTalk <-> NMEA Bridge is a single chip computer, that translates information between SeaTalk and NMEA.
It can read & write NMEA and read & write SeaTalk data.

In combination with the optional LCD Display, it is also a SeaTalk & NMEA data display.
This creates a Seatalk and NMEA repeater instrument for use at the chart-table.
With this display you can see data like speed, depth, position, windspeed, waypoint info, etc. combined from both systems ( SeaTalk and NMEA ) on one display.

bigger picture - just click on it.

The repeater has 1 SeaTalk bus connector and 1 serial port for NMEA or PC connection
  • ATmega32 Processor
  • 1 * SeaTalk Port ( read & write SeaTalk )
  • 1 * NMEA Port ( RS232 & RS422 )
  • On board volatage regulator
  • LCD display (optional)
  • Boot loader (to update to new Software Versions)
For more details please see -Users Manual-

A bigger picture ? - just click on it !

Here are two simple examples on what you can do with the SeaTalk NMEA Bridge
Connect your SeaTalk Instruments to your NMEA Network
If you have a Raymarine St60 Tridata, a ST40 Wind Instrument or other SeaTalk devices, you can let the SeaTalk NMEA Bridge translate Information from SeaTalk to NMEA. With this function a navigation notebook or a chartplotter can now display wind direction, wind speed, water depth, speed over water and much more. Send Data from your NMEA Devices to SeaTalk Instrumens The speed over water function of a ST60 tridata needs to be adjusted. The paddle wheels are different, waterflow arround different types of boat hulls are different - therfore your log need propper adjustent in order to display a correct speed over water. With the SeaTalk Nmea Bridge, you can send speed information from your NMEA GPS to the SeaTalk Instrument. This makes adjustment accurate, easy, fast. These are just two verry simple examples. With the SeaTalk NMEA Bridge you will many functions and features that havn't benn possible before.

SeaTalk datagram coding/decoding
  • Depth
  • Water temperature
  • Instument Light
  • Speed over water
  • Speed over ground
  • Course over ground
  • Apparent wind speed & angle
  • Total & trip milage
  • Latitude & longitude
  • Time & Date
  • Compass heading
  • Rudder position
From NMEA Protocol it reads GPRMC, xxMWV, xxMTW, xxDBT etc.
  • Position Lat/lon    ( RMC, GLL )
  • GPS status ( RMC, GLL) 
  • Speed through Water ( VHW )
  • Speed over ground (RMC)
  • Heading (HDM, HDG)
  • Time (RMC,ZDA)
  • Date (RMC,ZDA)
  • Water temperature (MTW)
  • Waypoint Information (RMB)
    Distance, Bearing, XTE, Name
  • Waypoint Information (APB, BWC - only for Bridge without LCD Display )
  • Depth below transducer (DBT)
  • Depth below Keel ( DPT)
  • Water temperature (MTW)
  • Total & Trip Milage (VLW)
  • Wind angel & speed (MWV)
Status: Info on LCD Display.
  • Speed through Water ( from NMEA or SeaTalk )
  • Speed over ground ( from NMEA )
  • Depth ( from Seatalk )
  • Water temperature ( from SeaTalk )
  • Position Lon/Lat ( from NMEA or SeaTalk )
  • Time
  • Apparent wind speed & angle ( from NMEA or SeaTalk )
  • Route / Waypoint names, bearing, cross track error, distance.
    ( Read from NMEA Gps )
Functions : Read NMEA Data -> Send to SeaTalk bus
  • Speed over Ground ( SeaTalk 52 )
  • Speed through Water
  • LAT & LON ( SeaTalk 51 & 51 )
  • Water Temp ( SeaTalk 27 )
  • Special SeaTalk sentence $STALK,xx,yy,zz.... ( Sends any SeaTalk)
  • Trip & Total Milage( SeaTalk 25 )
  • Course over Ground
  • Compass course
  • Apparent wind speed & direction
  • Next Waypoint Name, Direction, XTE
Functions: Read SeaTalk -> Send to NMEA port
  • Depth ( $IIDBT )
  • Apparent. Wind speed. & angle ( $IIMWV )
  • Speed through water ( $IIVHW )
  • Compass heading ( $IIVHW and $IIHDM )
  • Water Temp. ( $IIMTW )
  • Trip & Total Milage( $IIVLW )
  • rudder position ($IIRSA)
  • Position from SeaTalk GPS ( $IIRMC, $IIGLL )
  • Speed over Ground from SeaTalk GPS ( $IIRMC )

The pushbutton

The bridge comes with a pushbuttons.
The pushbutton is used to switch between different display pages.
Another function is to switch on/off the display illumination.

Page1: Speed, Position,Trk etc. Page2:Wind data, Compass, time etc.
bridgelcd1kl_200 bridgelcd2kl_200

Page 3: Route & Waypoint Info

If the bridge is connected to other instruments on the SeaTalk bus, it also switches on/off the lights of the other SeaTalk instruments. The other way arround also works. If you switch on the light on any of your SeaTalk instruments, the illumination of the display is also switched on. ( This Function can be disabled)


The SeaTalk NMEA Bridge project is sitll an active project. The Software will be improved continuously.
From the feedback of the users, new function will be added.
The Sources of the software is available. If you know how to programm an AT-Mega Processor in "C", you can change the software to whatever you like.

Special Functions

The Bridge has a few special function for those of us who want to learn more about SeaTalk.
The Bridge can be configured to send all - even unknown - SeaTalk sentences to the NMEA Port.
It will send a "$STALK,xx,yy,zz...." record for every incomming SeaTalk sentence.
With this function we can monitor the SeaTalk Bus and we can learn and decode new SeaTalk sentences.

You can order a SeaTalk NMEA Bridge at our web-shop. Before ordering please read the -Users Manual-
to make sure that you really get what you need. Kasse
Order a SeaTalk NMEA Bridge in our WebShop

Note: Meanwhile we have a new pcb version 3.5. and new Software Version 1.45
        New added : send next Waypoint data to your SeaTalk autopilot.
Latest news, details and discussions about this changes can be found in our Forum. New ideas, discussions and sugestions are allways welcome.

Note: We have shiped quite a few bridges and We're still extending the functions.
The boards are on boats in Germany, Great Britain, Netherlands, New Zealand, France, Singapore, Australia, Canada, Sweden ...... The latest change is Display of route and waypoint information and send waypoint data to SeaTalk.

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