There are several hardware devices that will provide translation and conversion of Seatalk/SeatalkNS to NMEA.

See these forum threads:
http://www.cruisersforum.com/forums/f134/raymarine-seatalkhs-data-in-ope...
http://www.cruisersforum.com/forums/f134/connecting-seatalkng-138727.html
http://www.cruisersforum.com/forums/f134/sending-routes-to-raymarine-evolution-autopilots-221205.html

NOTE: Differences between NGT-1 and NGW-1

See this page for links to Ocenav's capable devices. Ocenav - Nmea0183, Nmea2000 and Seatalk Converter with Wifi. Ocenav does it all. For example, the ATM 105 will simplify your wiring with integration of Nmea0183, Nmea 2000 and Seatalk with Wifi converter. Interconnect all instruments. 3 Models to choose from. Compatible with all major manufacturers (Raymarine, Garmin, Simrad, Lowrance, Furuno, B&G, NKE, VDO) sending data to all mobile apps. They allow pilot control from navigation applications (OPENCPN, MaxSea, iSailor, etc …) in track mode. The optional ATM 105-B remote control allows control of the autopilot (small portable remote control attached to a neck lanyard). Check the link above for more information.

Acticsense NGW-1 (two programmable versions one for Instruments, another includes AIS)

NGW 1 is NMEA 2000—→NMEA 0183 —→ PC via USB. OpenCPN can use NMEA 0183

• If you want to transfer certain NMEA 2000 messages from an existing bus system in your boat to NMEA 0183 and to OpenCPN the NGW 1 would be the best choice. Search the Actisense site for more info.
• If you want to transfer pure serial NMEA 0183 to USB and OpenCPN USG 2 would fit.

The Actisense NMEA 2000 to NMEA 0183 Gateway is the easiest way to link between a boat’s old and new data networks. Bidirectional converter from NMEA 0183 to NMEA 2000. Allows use of NMEA 0183 devices on NMEA 2000 network. 10-35 VDC.

Acticsense NGW-1-STNG converts NMEA 0183 data into SeaTalk NG and vice-versa, providing seamless integration with Raymarine products. The NGW-1-STNG option combines a standard NGW-1-ISO with a Raymarine SeaTalk NG adapter cable to interface legacy instruments to the NMEA 2000 based SeaTalk NG bus.

• Now available with the SeaTalk NG to NMEA 2000 adaptor Cable - STNG-A06045
  
• Upgrade NGW-1-STNG to NGW-1-STNG-AIS with a simple firmware update operating at 38400 baud. to get all data on a NMEA 2000 network, including AIS. With Opencpn Com port set to 38400 access and display all data and control the autopilot. If the autopilot is on your NMEA 2000 network it will respond to commands at 38400. To add wifi you could use Actisense W2K-1 NMEA 2000 to WiFi Gateway but it is not bi-directional. Apparently an upgrade is in the works. (YachtDevices YDWG-02 unit may work).

NGT 1 is NMEA 2000 —> PC via USB.
OpenCPN 5.8.4 + can use NMEA 2000 and NMEA 0183
For OpenCPN use a NMEA2000 - NMEA0183 - PC USB device.

• If you have Nmea2000 you can use NGT-1 and install Signal K server to convert 2000 to 0183 that OpenCPN understands.
• This way is more future proof than NGW, as you can have access to all NMEA 2000 data including data that has no standard sentences in 0183, like electrical and engine data.
• If you have Nmea0183 then NGT-1 is a wrong choice and you should just get a serial to USB converter. Digitech makes a USB to RS422/485 converter which can be had for around A$50. NMEA 0183 uses the RS 422 electrical specification.

Actisense W2K Nmea Wi-fi Gateway NMEA 2000 backbone to any device (e.g. laptop, tablet or smartphone) connected to it via Wi-Fi. Built-in conversion of NMEA 2000 messages into NMEA 0183 sentences thus allowing a wide variety of vessel data (e.g. position, speed, course, wind speed, depth, engine data, AIS messages etc.) to be shared with NMEA 0183 compatible software applications running on connected devices.

All the data received (or a selected subset) can be logged to its internal micro SD card for later downloading to use for analysing the voyage. This is very useful for analysing race data, generating logbooks, diagnosing problems or even sharing your voyage details. Approximately 16 days of data can be stored on the pre-installed industrial grade micro SD card, which can be upgraded should the user require more storage.

Yachtd Devices devices may be less expensive than Actisense.

Yacht Devices has two terrific ways to get data from a SeatalkNG (or DeviceNet/NMEA2000) network into OpenCPN. The first is the direct method with a YDNU-02. NMEA2000 USB Gateway. The YDNU-02 is a USB to N2K adapter that comes in two flavors – one with a SeatalkNG connector and the other with standard DeviceNet. Simply plug this end into a “drop cable” T or a white SeatalkNG connector and plug the other end into a USB port on your computer. Drivers for Windows 10, MacOS and Linux are not required. Drivers for Windows 8 and below are maintained on the company's download page at https://www.yachtd.com/downloads/.

Setup for the YDNU-02 should be automatic. If internal settings need to be done or firmware upgrades need to be applied, it is done through a Terminal interface that is less than intuitive. Please see the manual for how to do this as it can be quite involved. Manuals can be downloaded from the same site https://www.yachtd.com/downloads/.

Setting up the YDNU-02 in OpenCPN is very straight forward. In the “Connections” pane of the Options menu, click “Add Connection.” Set the connection to “Serial,” select the YDNU-02 from the “Data Port” (If you don't know which one it is, check this before plugging it in and it will be the new one after plug in) and select the baud rate to 230400 from the drop down menu. Give it a name of YDNU or something so you know which connection it is and “Apply”. Now you are receiving NMEA0183 data into OpenCPN through your USB port. This can be verified in the “Show NMEA Debug Window.”

Please note: the YDNU can operate in one of four different “modes.” They are: AUTO, NMEA0183, NMEA2000, and RAW. Its default setting is AUTO and plugging it into OpenCPN should let it know to conver NMEA2000 data from the network and send it in NMEA0183 format. OpenCPN doesn't work with NMEA2000 or RAW data, so those modes should be avoided. Out of the box, it should work just fine in AUTO mode. Please see the User Manual for more information.

For boats with WIFI aboard, the WDWG is an excellent alternative to the YDNU. It is a small device in two flavors (same as YDNU) for either SeatalkNG or DeviceNet. It has no cable attached. Once plugged into the network and receiving power and N2K data, it creates a small WIFI connection that you can connect to with your computer and handheld devices to recieve N2K data over TCP/IP. It can also connect as a client to a boat's WIFI router and can act as a connection to send N2K data and converted NMEA0183 data to all your wireless devices connected to your boat's router, thereby putting all your marine data onto your boat's LAN without disrupting your regular internet service by having to disconnect from your router to connect to the YDNU for you marine data information. Unlike the YDNU-02, the YDWG is configured through a web interface and it much easier to control settings and update firmware.

Assuming you have a WIFI connection to it and have turned the server “on” in the YDWG, connecting OpenCPN to the YDWG is simple. In the “Connections” pane of the Options menus, choose “Add Connection.” Set the connection type to “Network” and select the network protocol you want to use, either TCP or UDP. Enter the IP number off the YDWG. If you have changed the IP by connecting it as a client to your boat's WIFI router, you will need to know what that IP address is (again, please see the manual). If you are using UDP, the IP will be 0.0.0.0. Enter the “Port” number and click apply. Port number is defined in the web interface, but the defaults are 4156 for TCP and 4157 for UDP. Enter your user comment so you'll know what device you are connected to and click “Apply”.

The YDWG can be set up with three internal servers to send TCP, UDP, and RAW data all at the same time, depending on the connection. OpenCPN doesn't read RAW data, so that server will be of no use in this senario. Please see other areas of this manul for the differences in TCP and UDP. The YDWG also offers a webserver with simple, customizable pages of gauges displaying network data that can be connected to with any wifi connected device and a web browser.

Both the YDNU and the YDWG act as NMEA2000-to-NMEA0183 translators between a marine network and OpenCPN. They both have bi-directional capabilities with features that help translate and send data to Raymarine Autopilot, as well as auto confirm waypoint advancement for the autopilot. Yacht Devices also has other options available beyond the scope of these two offerings.

One example: Yacht Devices now offers an ethernet version of the their network connectors. It is assumed it operates similarly to the YDWG, but with a wired connection ethernet connection instead of the WIFI connection.

I was following this nice guidance above for using the YDNU02 adapter, which looks straightforward enough…

Unfortunately, it did not work from the start. I then started digging a bit and alas, eventually I found out that the information presented in the “easy approach” via System Settings” on a Mac is not the same as when using the Terminal application. See the screenshot attached. The System Settings is somehow cutting off the last digit, it seems.

So, not sure whether this is something special for my case, but also look at the Terminal application using the ls command as seen to double check, if it does not work out of the box.

QK-A034 Bi-directional WiFi to NMEA 2000 Gateway Multiplexer with NMEA 0183 and SeaTalk input options $280 https://www.quark-elec.com/product/qk-a034-nmea-0183-seatalk-multiplexer-with-nmea-2000-usb-wifi-outputs/

Seamless connection of NMEA 0183 and Raymarine SeaTalk1 sensors, NMEA 2000 equipment and WiFi and USB devices.

  NMEA 2000® certified product
  Combines different data sources into one cohesive system
  Bi-directional NMEA 2000, WiFi and  USB
  Additional allows for adding three NMEA 0183 inputs and a SeaTalk1 bus input to the NMEA 2000, USB and WiFi data
  NMEA 0183 output (choose A034-B option)
  A powerful MPU converts, combines, filters and routes your data with minimal user configuration required
  Filtering functionality removes redundant or unnecessary data
  Routing functionality decreases risk of data over-flow

Quark-Electronics has a broad range of marine electronics.

From: $388.00 From: $283.38

SeaYak ST1 to NMEA USB Bridge http://www.yakbitz.com/ST1toUSB1.aspx CF Thread

Excellent overview of Seatalk, Seatalk1, SeatalkNS: Boat Projects: Beginners Guide to Raymarine's Seatalk and Derivatives

Raymarine Seatalk or Seatalk1 to/from Nmea0183 Bridge Converter E85001
Raymarine NMEA Multiplexer E55059
Raymarine SeaTalk NG Networking
PC/SeaTalk/NMEA Interface Box
Raymarine NMEA 0183 Multiplexer
Raymarine Seatalk - NMEA bridge for Brookhouse multiplexer
Thomas Knauf a SeaTalk Technical Reference
Shipnetwork OpenSeaMap-dev
Miniplex NMEA 0183 Multiplexers

For direct connection to PC or Laptop device use an FTDI USB to Serial Converter.
USB RS232 Cables

The E55053 SeaTalk 2 / NMEA 2000 Interface Cable (1.5m) is for connecting E-Series displays to Raymarine SeaTalk 2 or 3rd party NMEA 2000 Devices. The SeaTalk 2 / NMEA 2000 Interface Cable features a twist-lock connector at the E-series display end, and a standard 5-pin waterproof SeaTalk 2 style connector at the other.

The E55054 SeaTalk / Alarm Output Interface Cable (1.5m) is for connecting E-Series displays to Raymarine SeaTalk instrument networks. Also supports connection to an external alarm. The SeaTalk / Alarm Output Interface Cable 6-Pin twist lock connector a E-Series display end, and wire leads at the other.

The E85001 PC/NMEA/SeaTalk Interface Box converts signals between SeaTalk, NMEA 0183, and RS232 formats. Enables RayTech navigation software to converse in SeaTalk with compatible devices. Can be used to host PCs running NMEA based navigation software on a SeaTalk network. Also supports operation of the Raymarine Main Alarm when an alarm condition exists on the SeaTalk bus. This item is no longer available

The E86001 PC Serial Data Cable (2M) is used for connecting computers running RayTech navigation software to the E85001 interface box. Also used to tie NMEA GPS units to a PC's serial data port. The cable is fitted with a screw-lock DB-9 female connector on one end, and bare wire leads at the other, suitable for connection to your GPS or PC interface

Raymarine Converter Panbo http://www.panbo.com/archives/2010/08/raymarine_seatalk-seatalkng_conver...
Raymarine SeaTalk 1 to SeaTalk ng Converter Kit
Model #: E22158 Defender Item #: 254238 $87.99
http://search.defender.com/search.aspx?expression=254238&x=0&y=0
Works with Select SeaTalk 1 Instruments, GPS sensors and LifeTag,
Easy Plug-and-Play Connectivity with SeaTalk ng Networks. Good for ST60 Instruments.
Use the Panbo “N2K Cable Mixxing not a big whoop” directly below to connect to Nmea2000.

Modify Raymarine Seatalk NG cable by adding a Nmea2000 Adapter
Panbo: “N2K, cable mixing not a big woop” by Ben Ellison and posted on Feb 5, 2008
http://www.panbo.com/archives/2008/02/n2k_cable_mixing_not_a_big_woop.html

Raymarine SeaTalk NG To NMEA2000 DeviceNet Male Connector, Adapter Cable
Mfg #:A06046Defender Item # : 257913 $28.99
http://search.defender.com/?expression=257913&x=0&y=0
NMEA 2000 micro male connector on one end and SeaTalk NG connector on the other end
Used when connecting NMEA2000 standard devices to Raymarine SeaTalkng data network & visa versa.
The adapter cable has a standard white Raymarine spur connection on one end, and a NMEA2000 DeviceNet Male connector on the other. The adapter is approximately 10-inches long. This adaptor has a DeviceNet connector with pins (“male”). That's what you need to plug into a DeviceNet T-connector as the drop cable.

“I have been advised that these connections will send and receive data both ways.”

“As it turns out, I could not get either of those cables to resolve the ambiquity, and I made my own by cutting some other cables in half and splicing them. (A male devicenet connector at the tee end of every drop (or “spur” in STng talk) because a standard tee has two female and one male connectors. ) http://www.panbo.com/forum/2009/08/nmea-2000-and-seatalkng.html –Seatalk-to-STng converter also produces valid NMEA 2000 PGNs…”

“As far as I can determine, True Wind info is not present on the Seatalk bus, in either Seatalk1 or SeatalkNG, at least in a hybrid system. I have ST60 displays and ST70 pods and displays, and I can only find Apparent Wind data present on either bus. Which means that each display must be calculating its own True Wind data.”

Seatalk/Seatalk1 (3wire) to Nmea 0183 Bidirectional - gadgetpool.de

• http://www.gadgetpool.eu/product_info.php?products_id=70
• http://www.gadgetpool.eu/

1. There are issues with the translation of SeaTalk to NMEA ( and vice versa ), and the openCPN users should know that.
2. I still hope I can solve it - but until than, the openOpn community and the SeaTalk NMEA Bridge users should know what difficulties they can expect.

Frank advises that the firmware for the Seatalk Tiny Converter can be downloaded at: http://www.gadgetpool.eu/nuke/downloads/gadgets/SeatalkNmeaLink/stLinkV1_73.hex http://www.gadgetpool.eu/nuke/downloads/gadgets/SeatalkNmeaLink/stLinkV1_73.eep

and the manual can be found at: http://www.gadgetpool.eu/nuke/downloads/gadgets/SeatalkNmeaLink/ManualUsbV3-5_OptoSw1.70.pdf also Frank has provided the revised hex code and the update software below. Updated Software

Also he advises that Sourcecodes are available from me. If anyone want's sources - just drop me a mail from the website GadgetPool where there are other multiplex devices available.

(NOTE: This problem is now fixed with the software update above.) This note applies to older Tiny Seatalk Devices that have not had the software updated. There were three serious problems with the Bridge's logic, and the side by side comparison of the raw STALK datagrams and the translated NMEA sentences show the issues:

1. Datagram 53 outputs COG, and Knauf's reference work says this is in degrees magnetic, not in degrees true. In my data dump example, I get a datagram 53 that gives 359 for COG. Given that my COG as seen from my track is clearly 015T, that confirms that datagram 53 is in degrees magnetic. The issue is that the Bridge uses this value directly in RMC sentences, which require COG true. So that's why my COG predictor line is off - it's giving me the value of datagram 53 which is in degrees mag. Suggested fix: RMC field 8 should be COG true, not COG mag; use datagram 53 and correct for deviation, which is in datagram 99.
2. The output of Datagram 53 also gets inserted directly into field 1 of the VHW sentence. I think this is also incorrect. VHW, according to the NMEA references should be heading only, given in both true (field 1) and magnetic degrees (field 2). There is no COG data in a VHW sentence, but I think the Bridge is using datagram 53 (COG mag) in field 1, and the mag heading from datagram 84 or 9C in field 2. When I filter out VHW sentences in OpenCPN, my ship heading is correct, but when I allow them, I get an incorrect ship heading. So I think OpenCPN uses field 1 in preference to field 2 to determine heading. At any rate, I think the VHW sentence construction is wrong. Suggested fix: VHW field 1 should be HDG in degrees true, calculated from magnetic heading and deviation, not COG.
3. In the file stAlldata.h, the variables latPositionF and lonPositionF (fraction of minutes) are defined as type u08, so have a length of 1 byte. They therefore only have the precision to store fractions of minutes at 0.01 minute resolution. This is fine for datagrams 50 and 51, which use two bytes & 0x7FFF (so 15 bits, with the 16th bit used for N/S or E/W) to store minutes and fractions of minutes, and so can only output 0.01 min precision. The SeaTalk reference says that 50 and 51 only output stable filtered position. A precision of 0.01 minute is about 18.5 m, this gives a very choppy track and makes the Bridge output useless for things like anchor alarms. Knauf says that Datagram 58 is the raw position data. This datagram uses a full two bytes for minutes and fractions of minutes, and outputs to 0.001 min precision, or approximately 1.85 m precision. This is much better for navigation. Suggested fix: latPositionF and lonPositionF would have to be u16 (two bytes) in size to be able to store the necessary three decimal places that are output by datagram 58. Because datagrams 50 and 51 only output 0.01 min precision, additional logic would be required to prefer datagram 58 and ignore 50/51 if 58 is available on the bus.

More minor issues:

1. Datagrams 23 and 27 are both water temperature, but datagram 27 is given in degrees C with 0.1 degree precision. Datagram 23 is given in degrees C and in F, but to 1 degree precision. The SD128 outputs an MTW sentence for both datagrams, so you get ping pong values for water temperature like 16C, 16.7C, 16C, 16.7C etc. It's quite noticeable on both the bridge display and OpenCPN. Suggested fix: If datagram 27 is available on the bus, ignore datagram 23 (i.e. use only data with highest precision level)
2. The same is true for STW - there are two datagrams that provide it, and each has a different degree of precision. If the higher precision datagram is available, the lower one should be ignored.

1. Be aware that older versions of Tiny Seatalk Bridge should not be used for navigation until the software is updated.