[DG] [DG11] NMEA 0183 to ST2000 Queston

[nssailor]

Hi,
I just bought a new plotter (B&G Vulcan 9) and am trying to integrate it (while on the hard) into my system which includes an ST2000+ tiller pilot.
The plotter goes through an Actisense converter (NGW-1 2000 to 0183) which then feeds into a Raymarine NMEA multiplexer along with wind, depth, speed, etc. from Tacktick NMEA. All seems to work well with each other, however, the 0183 stream that gets to the ST2000 from the Raymarine multiplexer output passes Bearing to Waypoint as True in RMB sentence. Variation is output from the multiplexer but in the HDG sentence which is not in the ST2000 list of recognized NMEA sentences. I have put the variation manually into the ST2000 but this does not seem to change the displayed bearing.

If the variation is programmed into the ST2000, will it steer correctly despite displaying the True bearing to waypoint? If not, assuming I can change the Actisense conversions, what would the best sentence be to provide the information needed?

Thanks for any help you can offer.
Colin

[Louise - Raymarine - Moderator]

Dear nssailor,

Thank you for your post.

What variation are you manually applying to the ST2000? Are you also aligning the heading to match the ships compass?

The heading displayed is only ever shown as magnetic on the ST2000, it does not accept heading data as it has the internal compass and is a closed system.

The manual variation will be applied by the pilot to the true bearing to waypoint as the ST2000 only displays magnetic variation.

Have you true or magnetic selected on your chart plotter?

Many Thanks
Louise

[Louise - Raymarine - Moderator]

Dear nssailor,

Thank you for your post.

What variation are you manually applying to the ST2000? Are you also aligning the heading to match the ships compass?

The heading displayed is only ever shown as magnetic on the ST2000, it does not accept heading data as it has the internal compass and is a closed system.

The manual variation will be applied by the pilot to the true bearing to waypoint as the ST2000 only displays magnetic variation.

Have you true or magnetic selected on your chart plotter?

Many Thanks
Louise

[nssailor]

Hi Louise,

Thanks for the reply. I am applying -17 to the ST2000 (local variation here in NS is 17W). The boat is on the hard at the moment but the boat fluxgate compass and the compass heading on the ST2000 are within a couple of degrees (and I suspect will match when both are calibrated when the boat is in the water again).
The ST2000 is being fed a bearing to waypoint and distance via the NMEA stream and what is being displayed is the true bearing that the stream is passing. My plotter is displaying magnetic but seemingly will only pass true bearing via NMEA.

To clarify with an example:

Boat fluxgate compass displays heading as 17 deg Mag. ST2000 displays heading as 21 deg Mag (neither has been calibrated recently so I'm sure will match when they are). I put a waypoint in the plotter which is directly in front of the bow of the boat at a distance of 1.5nm. Plotter shows bearing to waypoint on its display as 17 deg Mag; dist 1.5nm. RMB sentence shows bearing to waypoint as 0 deg True; dist 1.5nm. Tillerpilot displays bearing to waypoint as 0 deg; dist 1.5nm.

Does the tillerpilot recognize that the bearing it receives is True? Will it correct it with the variation I have put in via calibration level 9? What should it display?

Colin

[Louise - Raymarine - Moderator]

Dear nssailor,

The ST2000 should apply the magnetic variation you have manually input to the bearing to waypoint being displayed on the ST2000. The ST2000 accepts the RMB sentence and will apply the variation.

When putting the pilot into track mode are you seeing the expected true or magnetic value?

You should see the magnetic value on the display.

Many Thanks
Louise

[nssailor]

Hi again Louise,

Unfortunately, the situation is as I gave in the example. The tillerpilot displays the expected True bearing on the display. I have attached pictures showing:

1) Chartplotter - display is true north up; waypoint is placed at 1 deg True = 18 deg Mag; at 1.01nm. Chartplotter displays 18 deg M to waypoint;

2) Information is passed to both ST2000+ tillerpilot and TackTick network via the Actisense converter and Raymarine NMEA concentrator.

3) TackTick display shows 17 deg Mag to waypoint (rounding difference of 1 degree) and 1.01nm.

4) Unfortunately tillerpilot shows 0 deg and 1.01nm. In other words tillerpilot is displaying True (and presumably will attempt to steer to 0 deg Mag??) I also show the ST2000 display showing the correct -17 variation is programmed in.

It would appear the ST2000 will not apply the variation to the True bearing to waypoint?

Colin

(03-10-20 09:02 AM)Louise - Raymarine - Moderator Wrote:  Dear nssailor,

The ST2000 should apply the magnetic variation you have manually input to the bearing to waypoint being displayed on the ST2000. The ST2000 accepts the RMB sentence and will apply the variation.

When putting the pilot into track mode are you seeing the expected true or magnetic value?

You should see the magnetic value on the display.

Many Thanks
Louise

[Louise - Raymarine - Moderator]

Dear Nssailor,

Are there other NMEA0183 sentences on the data network with bearing to waypoint?

My suggestion is to turn off local magnetic variation the pilot. Currently the correction is only cancelling out he magnetic variation difference. The pilot is seeing the magnetic variation to waypoint, this is available in BWR and BWC. Both NMEA0183 sentences offer magnetic and true bearing to waypoint data, I am unsure if the pilot prioritises any of these sentneces, I would need to investigate further.

We can be sure that with a -17 degree magnetic variation applied to the pilot and it is displaying 0' when the bearing is 17' magnetic on the plotter, you are just negating a bearing with the magnetic variation already applied.

Many Thanks
Louise

[nssailor]

Hi again Louise,

Unfortunately, it is not behaving as you suggest. I took the magnetic variation out of the tillerpilot, depowered and repowered, and it still displayed 359 degrees (as it did before taking it out). I also put the variation back in. In all circumstances it displayed 359 deg as bearing to waypoint which was the true bearing. I've also attached the sentences that are on the network. The RMC sentence is only displaying true bearing (not magnetic) and I don't believe there is any way to change that.
I'm puzzled that there is no change on the tillerpilot whether the variation is programmed in or not.
-17 programmed in does not subtract 17 from the bearing supplied. It just indicates that magnetic north is west of true north. In fact, it should then add 17 to the true bearing.

Colin

[Louise - Raymarine - Moderator]

Dear nssailor,

Thank you for the response.

I have tried to source the original code from when the unit was designed, I cannot confirm if the ST2000 does apply the variation to a BTW in true.

It looks like it does not I am afraid. If you can send out the bearing to waypoint NMEA0183 sentence from your plotter with magnetic applied - it should show this.

On this occasion I cannot help further.

Many Thanks
Louise