Furuno GD1700 and Raymarine Smartpilot S2



Hi all,

this is my first post so let me introduce myself: my name is Francesco and I come from Italy. I'm 40 years old and I use to sail with my family on a "Dufour 40" Sailing boat that's located near Genova, in the mediterranean sea.

I admit I crossposted on the Raymarine forum the same question :oops: I hope you'll never mind :)

This boat is 10 years old and the previous owner installed all the instrumentation. In particular there are:

Furuno Chartplotter GD1700
Furuno GPS Receiver GPS32

Raymarine Smartpilot S2 (not sure) + ST6001 controller
Raymarine ST60 Wind
Raymarine ST60 Tridata
Raymarine ST60 Graphic Display

I'm quite new to nautical instruments, so please, excuse me if I use wrong terms or I miss something.

The GD1700 and the GPS32 are connected using the DATA1 port. I think (quite sure) that the GPS32 send position informations to the Chartplotter. Even if the GPS32 is a navigator, I only use the chartplotter for navigation purposes (I don't set waypoint on the GPS32, only in the Chartplotter).

Raymarine instruments are connected using Seatalk 1.

Is there a way to connect the Chartplotter to the Raymarine autopilot? If so, what will I be able to do once they are connected? (e.g. let the autopilot follow the route on the chartplotter?)

On the autopilot main unit there are two NMEA port (2xIN e 2xOUT). I think that NMEA should be used to connect.

Just to remember, those are NMEA senteces the GD1700 is able to send:

AAM - Waypoint Arrival Alarm
APB - Auto Pilot B sentence
BOD - Bearing Origin to Destination
BWC - Bearing using Great Circle route (BWR - Bearing using Rhumb Line)
DPT - Heading – Deviation & Variation
GGA - Fix information
GLL - Lat/Lon data
GTD - Geographic Location in Time Differences
MTW - Water Temperature
RMA - recommended Loran data
RMB - recommended navigation data for gps
RMC - recommended minimum data for gps
VHW - Water Speed and Heading
VTG - Vector track an Speed over the Ground
WPL - Waypoint Location information
XTE - measured cross track error
ZDA - Date and Time
HDT - Heading – True
HDG - Heading – Deviation & Variation
MWV - Wind Speed and Angle
TTM - Tracked Target Message

and those are the NMEA senteces the chartplotter is able to read:

Own ship’s position: GGA>RMC>RMA>GLL
Ship’s speed: RMC>RMA>VTG>VHW
External waypoint: RMB>WPL>BWR>BWC
Heading (True): HDT>HDG>HDM
Depth: DPT>DBT
Temperature: MTW
Time: ZDA
Other ship’s information: TTM
Insight satellite information: GSV
Wind speed and angle: MWV>VWT>VWR

Thank you for your help
Dear Johnny,

thank you for your reply! Unfortunately the specs on the Raymarine manual only say "NMEA v2.3 In/Out" with no other informations.

By the way, I omitted something important and the general situation has changed.

I omitted to tell you I also have a Furuno Radar connected to a device that is similar to a GD1700 but it has a connection for the Radar antenna on the back: it's a 1722 Radar/Chartplotter.
I also have a Furuno Navtex (NX300).

I was wrong about the Raymarine course computer model: it's a "150 Course Computer" and not a "S2".

Yesterday I went on board since the display (gd1700) and the "radar/chartplotter" (1722) didn't connect, so I changed the network cable. Now they work perfectly and I'm able to see the radar and the charts coming from the 1722 on the GD1700 display: very good :furuno

Probably, after changing the cable, some already defective Seatalk cable or connection, broke, and the Seatalk connected instruments are partially dead. The important thing is that, trying to find the defect, I investigated on the existing Furuno instruments connections: it seems like the GP32 NMEA OUT is connected to the Navtex NMEA IN, to the 1722 DATA1 Port using NMEA IN pins, and, finally, to the NMEA IN on the Autopilot main unit (150 Course Computer).

I powered on the autopilot main unit, the Furuno GPS and a Raymarine Graphic Display that is connected only to the seatalk network and I was able to read Lat and Long data on the Raymarine Graphic Display!!! That's the sign that NMEA between Furuno and Raymarine works :jump

Since the NMEA cables are in a very small box, it's difficult to understand the connections. Tomorrow I'll be on board again and I'll design a detailed schematics of the connections, and I'll be back to you trying to solve my confusion about connections and how to use instruments correctly ...

The Furuno GPS32 actually send position, heading and routes informations to every Furuno instruments and to the Autopilot main unit. That's a fixed point.

When I'll be able to have every connection working, I think I'll be able to let the Autopilot follow the route on the Furuno GPS (not the chartplotter since the chartplotter NMEA OUT is not connected to anything).

See you on Monday, and thank you for reading :spam
The GP32 NMEA output is White (+) and BLUE (-) for RS422 NMEA and/or Yellow (+) and Blue (-) for RS232 NMEA. RS232 can drive one RS232 listener. The RS422 output can drive up to three RS422 listeners depending on what they are. Radios are normally counted as two listeners because of the current they pull. Although you got it working, you will want to make sure you are not mixing NMEA types because it can damage your unit(s).
Dear Johnny,

thank you for your reply! I didn't post further more because Saturday I had to debug a problem I had on the seatalk network. I finally discovered it was caused by a defective wind instrument. On the remaining time I checked the existing connections and I designed this schematics:


I have just learned from you that the connections I found are correct since they use the white and blue wires on the GP32 for two listeners (the Autopilot and the Radar/Chartplotter).

I probably put at risk the instruments because i used the same white and blue wire to connect to my Personal Computer's RS232 port! I connected the white wire to the Rx pin and the Blue wire to the GND pin on the RS232. Next time do I have to use the Yellow wire instead of the White one?

I also tried to do a GOTO cursor on the GP32 and, after a while, on the Autopilot controller appeared the text "Next WPT?" and a heading to go to the next waypont that was the same I read on the GP32. So I had the confirmation that autopilot and GP32 talk together :D Very Good news! :jump

There are still some questions, just to uderstand which are the possibility of my instruments. I have data coming from the Seatalk network (wind data, speed over water, depth, magnetic heading ... ) and position and navigation data coming from the GP32 via NMEA.

On the chartplotter "input" I have "just" the GP32 data but no Seatalk network data. Same thing if I connect my PC. There is no Chartplotter output so I cannot communicate with the autopilot with the chartplotter (I cannot do a "GOTO Cursor" as I did Saturday on the GP32 and be listened by the autopilot)

I also have a Raymarine Graphic Display with a NMEA output that can do Seatalk to NMEA bridge.

How can I share NMEA and Seatalk informations between the Chartplotter, the PC and the autopilot?

I saw that there are some NMEA multiplexer also with WIFI or USB port. Do you think they are a good solution?

I know that there is not a real "problem" on the units but I would really like to better understand how those instruments interconnect.

I'm sorry if I do not speak correctly, please forgive me.

Thank you
I probably put at risk the instruments because i used the same white and blue wire to connect to my Personal Computer's RS232 port! I connected the white wire to the Rx pin and the Blue wire to the GND pin on the RS232. Next time do I have to use the Yellow wire instead of the White one?

Correct. When using the PC (RS232) you should use the yellow not the white wire.
Also note: your current label of the yellow and green wires of your drawing for the GP32 is not correct. Yellow is an output not an input.

If you always use the pilot, you could have the pilot send NMEA 0183 data into the plotter instead of the GP32. This way your plotter will get not only GPS but the other data as well. The only problem is to ensure you do not allow heading data on that plotter port. Only data 2 on the 7" is for heading. If you put heading into data one or three; you will have problems. Much depends on if the autopilot allows you to pick what data is transmitted.

Many users with only a single 7" display choose to use NMEA expanders and/or multiplexers. It can be helpful but remember 4800 baud rate only carries about 6 to 7 NMEA sentences.

Your English is good, especially when dealing with a technical subject. :cool