[TG] [TG11] SPX-5 / ST70 Issues

[vshtonov]

I have a system cobbled together from older parts and while it performs relatively well, I would like to fix a couple of issues if possible.

Sailboat, SPX-5 Wheel autopilot, ST70, ST6002 and ST6001 control heads interfaced to the autopilot via the Seatalk converter, Raymarine C80 chartplotter, remote keypad for the chartplotter and Sirrius SR50 weather receiver. All latest firmware.

I have two independent nmea 2000 networks, one is for the autopilot, the ST70 and the Seatalk converter to the 6001/2 heads and another one that connects the remote keypad and the weather receiver to the C80.

Finally, there is nmea 0183 10 Hz wind sensor feeding the nmea in of the autopilot and a Garmin DV44 that provides GPS signal. All of this works quite well, except:

Q1. The ST70 only displays magnetic heading. The other heads and the chartplotter can be set and display correctly either magnetic or true. My understanding is that something prevents the ST70 from showing true heading even if selected from the menus. What could be it? I have tried disconnecting the devices but still no luck.

Q2. The nmea in on the autopilot works well but I do not get fast heading output on the nmea out from the autopilot. If I connect the nmea 2000 output from the Seatalk converter to the Seatalk 2 port of the C80 I get fast heading output but my wind display (ST60+) that was showing wind fine would continue showing direction correctly but speed is reduced by a factor of ten, i.e. if wind is 10-12 knots, as soon as I connect the nmea 2000 to the C80, wind speed on the Seatalk 1 network goes to 1.0-1.2 knots, while direction is OK. Wind speed continues to be displayed correctly on the C80. My guess is that the C80 confuses the Seatalk 2 network somehow. Would a Seatalk 2 wind instrument correct this issue?

Q3. The SPX-5 compass alignment is 110 degrees, even though the fluxgate is mounted facing forward. Could this be an issue with autopilot or an indication of a failure mode? It steers OK. The fluxgate passes the resistance tests.

Q4. Would the SPX-5 autopilot work with an external KVH-1000 10 Hz compass? The manual suggests that this is possible while on this forum I have read that the fluxgate is still needed. The logic here is that I can feed the fast heading both to the compass and the C80 for MARPA? On a related note, if the Seatalk converter receives fast heading from the nmea 2000 port on the SPX, how often does it output it on the Seatalk network? 2 Hz or higher?

Q5. What would be the recommended upgrade? EV1+the biggest Axiom I can afford? Will the ST70 head still be useful or do I need a complete package upgrade?

Thank you,
Vassil

[Tom - Raymarine - Moderator]

Hello Vassil,

Quote:I have two independent nmea 2000 networks, one is for the autopilot, the ST70 and the Seatalk converter to the 6001/2 heads and another one that connects the remote keypad and the weather receiver to the C80.
...
Q1. The ST70 only displays magnetic heading. The other heads and the chartplotter can be set and display correctly either magnetic or true. My understanding is that something prevents the ST70 from showing true heading even if selected from the menus. What could be it? I have tried disconnecting the devices but still no luck.

I would suggest having the pilot, C80 and ST70 all connected on ST1 rather than STNG/NMEA2000. I don't think there's any benefit to having this split between ST1 and STNG, all of these products talk ST1 and that is likely to resolve that ST70 issue (which I expect is from Variation not being bridged across from ST1 to STNG.)

Quote:Q2. The nmea in on the autopilot works well but I do not get fast heading output on the nmea out from the autopilot. If I connect the nmea 2000 output from the Seatalk converter to the Seatalk 2 port of the C80 I get fast heading output but my wind display (ST60+) that was showing wind fine would continue showing direction correctly but speed is reduced by a factor of ten, i.e. if wind is 10-12 knots, as soon as I connect the nmea 2000 to the C80, wind speed on the Seatalk 1 network goes to 1.0-1.2 knots, while direction is OK. Wind speed continues to be displayed correctly on the C80. My guess is that the C80 confuses the Seatalk 2 network somehow. Would a Seatalk 2 wind instrument correct this issue?

The SPX range outputs heading on NMEA0183 or NMEA2000/STNG at 10Hz, but ST1 can only carry heading at 2Hz. Which NMEA are you using, 0183? If so, how are you confirming that it's not 10Hz? Do you really need 10Hz heading? That was commonly only used for radar-chart overlay and MARPA. Don't be tempted to try to connect NMEA0183 and ST1 to the C80: that's a recipe for NMEA data loops and therefore static or missing data. I would stick with ST1 and accept 2Hz heading on the C80.
Don't use the ST2 port on the C80 for standard navigation data: it was never fully implemented/approved for that purpose and is not expected to work fully.

Quote:Q3. The SPX-5 compass alignment is 110 degrees, even though the fluxgate is mounted facing forward. Could this be an issue with autopilot or an indication of a failure mode? It steers OK. The fluxgate passes the resistance tests.

If the heading data looks ok, don't worry about it.

Quote:Q4. Would the SPX-5 autopilot work with an external KVH-1000 10 Hz compass? The manual suggests that this is possible while on this forum I have read that the fluxgate is still needed. The logic here is that I can feed the fast heading both to the compass and the C80 for MARPA? On a related note, if the Seatalk converter receives fast heading from the nmea 2000 port on the SPX, how often does it output it on the Seatalk network? 2 Hz or higher?

Ok, this answers my question above. SPX can take external heading data, but this disables the internal rate gyro and AST steering algorithm. We'd only recommend this on a steel boat that couldn't use a standard fluxgate.
ST1 heading is always 2Hz maximum.

Quote:Q5. What would be the recommended upgrade? EV1+the biggest Axiom I can afford? Will the ST70 head still be useful or do I need a complete package upgrade?

NMEA2000. Getting everything on one standardised network, regardless of manufacturer, will likely resolve almost all of your headaches above.
Beyond that, yes, the EV pilots are miles ahead of the SPX in course-keeping accuracy, and the modern MFDs are even further ahead of the 15-year-old C80. If you were going to do one first I'd pick the MFD, along with a new STNG network, and then the autopilot later. Keep the pilot and ST600x displays on ST1 and everything else on NMEA2000/STNG, connected at a single point, your ST1-STNG convertor.

Regards,
Tom