Raymarine ST1000 tiller pilot and connection to chart plotter

[bremar]

My boat is a Hunter Minstrel 23 with an outboard well. I also have a Raymarine ST1000 tiller pilot which I understand can not keep a specific course because of the magnetic effect of the engine which is very close to the internal compass of the tiller pilot. The answer is a remote compass which you attach to the st1000 and then position somewhere up front away from the effects of the outboard.
However, I'm also considering a second hand cheap chart plotter such as a Garmin gpsmap 450 or 550S (with fish finder) Etc or other max £200 ish plotter/fishfinder for my Christmas present.
I think I can connect the ST1000 to a chart plotter and program the tiller pilot from there, thus doing away with the need to buy the remote compass (at about £80-£90.)?
These are the questions that I can't find answers to.
1. Is this correct? I.e. That it will replace need for the remote compass
2. On the Raymarine website it says connections NMEA 0183 input/SeaTalk. can I connect it to any NNME plotter or only to the older NMEA 0183 standard plotters
3. Is it simpler to buy a Raymarine plotter.

Thanks Bremar

 

[RupertW]

I'm not an expert on connecting pilots to chart plotters (and slightly dislike the concept of automated turns as I've seen them done in the Med and they are alarming).

However the heading cannot be determined by a chartplotter unless it already has a remote compass fed into it separately. All the chartplotter can do is use GPS to determine your track over the ground which is not precise enough at all for steering as it will either be so damped that it's too slow or more likely, so full of spurious innaccurate position readings that get averaged out that the tiller will twitch all over the place.

My second thought is surprise that the proximity of the engine stops it keeping a course. I have certainly had times where the actual heading shown on the pilot was innaccurate at at various headings due a nearby object but unless this is extreme if you set the course yourself, hit "Auto" the course should be fine even if the heading shown is 170 not 210 (or whatever).

 

[AntarcticPilot]

No, it isn't, or at least, not entirely. The Chart plotter doesn't have a built-in compass, so it will take the compass signal output from the tiller-pilot in the absence of other compass signals. I don't entirely understand how a chart plotter and the tiller-pilot interact, but it is certainly true that although it could manage without a compass signal to navigate to a waypoint, in practice an error-prone or faulty compass signal DOES interfere with the ability of the chart-plotter to navigate to a waypoint. I suspect that the chart-plotter says "Steer X magnetic course", and then checks the cross-track error until it becomes large enough for it to say "OK, move to Y course". The point is, the chart-plotter isn't replacing the controller in the tiller-pilot, it is simply giving it courses to steer. If it tried to continuously correct the course, it would interfere with the control feedback in the tiller-pilot, which is quite a complex and tricky algorithm.

 

[AntarcticPilot]

My second thought is surprise that the proximity of the engine stops it keeping a course. I have certainly had times where the actual heading shown on the pilot was innaccurate at at various headings due a nearby object but unless this is extreme if you set the course yourself, hit "Auto" the course should be fine even if the heading shown is 170 not 210 (or whatever).

From a previous thread, I think the problem is that the engine causes a varying compass offset - it's not the constant offset caused by a lump of iron, it's a varying magnetic field from the electrical system of the engine. There was a long thread about whether this could be shielded from the tiller-pilot (it can't!)

 

[RupertW]

From a previous thread, I think the problem is that the engine causes a varying compass offset - it's not the constant offset caused by a lump of iron, it's a varying magnetic field from the electrical system of the engine. There was a long thread about whether this could be shielded from the tiller-pilot (it can't!)

Ah - gotcha - that would make things awkward

 

[bremar]

Ok I think I've got it.
The tiller pilot has to have an accurate compass, remote or otherwise to properly respond to any imput from the gps chart plotter.
Think I may need to get the remote compass and see how it goes.

Thank you. Bremar

 

[shaunksb]

Ok I think I've got it.
The tiller pilot has to have an accurate compass, remote or otherwise to properly respond to any imput from the gps chart plotter.
Think I may need to get the remote compass and see how it goes.

Thank you. Bremar

I had exactly the same problem as you on my Jaguar 24 with a well and a Honda 9.9 in it.

However when I changed the engine to a Tohatsu 6hp the tiller pilot worked perfectly.

(Both engines have charging coils)

I can only think later engines have better suppression.

________________________

 

[pvb]

Ok I think I've got it.
The tiller pilot has to have an accurate compass, remote or otherwise to properly respond to any imput from the gps chart plotter.
Think I may need to get the remote compass and see how it goes.

That's not actually correct. You don't necessarily need a compass input at all. Your tiller pilot will respond to cross-track error messages from the plotter to maintain a course between waypoints, with no need for a compass. If, on the other hand, you just want to steer a course and then have the tillerpilot maintain that heading, you'll obviously need a reliable compass input.

 

[Ruffles]

i think the tiller pilot will still need a working compass to work in any kind of a sea.
Also XTE can be a bit of a pain. If you deliberately move off the line say, to avoid a ship, put it back on auto and it will take you back to the line rather than heading for your destination.

 

[prv]

That's not actually correct. You don't necessarily need a compass input at all. Your tiller pilot will respond to cross-track error messages from the plotter to maintain a course between waypoints, with no need for a compass.

Is that based on experience? If so, I find it extremely surprising. NMEA0183 XTE messages surely aren't frequent or precise enough to correct for every wave.

Pete

 

[LadyInBed]

That's not actually correct. You don't necessarily need a compass input at all. Your tiller pilot will respond to cross-track error messages from the plotter to maintain a course between waypoints, with no need for a compass. If, on the other hand, you just want to steer a course and then have the tillerpilot maintain that heading, you'll obviously need a reliable compass input.

To do this the AH needs to have a 'Track' function. I don't think that the AH1000 has, unless it's improved since I had one. I don't think it is capable of taking an external compass either.
If the engine is offset the same side as the AH, OP could try mounting the AH on the opposite side, as you can set it up for port or sbd mounting.
The expensive option is to upgrade to a 4000 which does have an external compass!

 

[pvb]

To do this the AH needs to have a 'Track' function. I don't think that the AH1000 has,

The OP mentioned an ST1000. The ST1000Plus certainly has a Track function.

 

[prv]

To do this the AH needs to have a 'Track' function. I don't think that the AH1000 has, unless it's improved since I had one.

This is the ST1000 - the ST stands for "SeaTalk" and means it can optionally accept navigation, wind, and speed data. One of the things this allows it to do is track mode.

I would still expect it to need a compass, though.

Incidentally, there is no mention in the manual of provision for any external compass source.

Pete

 

[pvb]

Is that based on experience? If so, I find it extremely surprising. NMEA0183 XTE messages surely aren't frequent or precise enough to correct for every wave.

XTE update frequency depends on the GPS/plotter, but is typically once per second.

 

[prv]

XTE update frequency depends on the GPS/plotter, but is typically once per second.

Whereas the standard compass for this era of autopilot uses an analogue connection so "updates" are continuous. Of course this will then be sampled into the software; I've no idea at what rate but I'm sure it will be many times per second. Standalone NMEA compass units generally run at 10Hz.

Separately from the rate consideration, the resolution of a Seatalk XTE message is one hundredth of a nautical mile - about 20m. More than sufficient for navigation, but it ain't gonna help the pilot know that the stern's just been slapped sideways by a wave, is it?

I say again, have you actually seen an autopilot working with neither an internal nor an external compass?

Pete

 

[pvb]

Separately from the rate consideration, the resolution of a Seatalk XTE message is one hundredth of a nautical mile - about 20m. More than sufficient for navigation, but it ain't gonna help the pilot know that the stern's just been slapped sideways by a wave, is it?

I can't imagine that the ST1000 is clever enough in Track Mode to respond to anything other than the XTE message. All the autopilots I've experienced have had a working compass.

 

[fergie_mac66]

We have a st1000 and link to a garmin 450s .It steers to a a route ploted on the garmin without difficulty keeping usually within 50 ft of the course in use .I have a socket at home for the garmin andalways take them home to plot routes and waypoints on the computer and transfer to sdcard for the Garmin. We have not found it a problem not using the compass but it takes a bit more planning over ten Nm to take full advantage of tidal flows

 

[fergie_mac66]

We been using it in track mode for 5 /6 years

 

[AntarcticPilot]

This is the ST1000 - the ST stands for "SeaTalk" and means it can optionally accept navigation, wind, and speed data. One of the things this allows it to do is track mode.

I would still expect it to need a compass, though.

Incidentally, there is no mention in the manual of provision for any external compass source.

Pete

I have the big brother, an ST2000. This has an internal compass, which owing to the nearby presence of a command mike, is in chocolate teapot territory (actually, it is usable, but not very reliable, and of course, the heading is incorrect if the tiller-pilot is disengaged). I fitted an external fluxgate compass, and the way the SeaTalk bus operates is that this overrides the compass signals from the ST2000; this appears to be functionality of the chart-plotter and ST bus rather than of the tiller-pilot. I think there are menu options deep in the chart plotter to specify which source is used for compass data, but as it was set up by an electronics company so I'm not sure.

I must admit there appears to be a fair amount of undocumented behaviour around all of this, and of course, mixtures of equipment from different manufacturers may exhibit totally different behaviours. Mine is all Raymarine, so it all operates together pretty harmoniously.

 

[John the kiwi]

I have an ST 1000 on my 26 ft trailer yacht which i originally set up on the starboard side of the cockpit. Right handed bias i think.
Transom mounted OB also on starboard side and quite close to the ST1000 when the motor was tilted.
Performance of the ST1000 under un-tilted motor was OK but when sailing with tilted motor, not so good.
I fitted an ST1000 mount to the port side of the cockpit and it was much better.
OB s have big fixed magnets in the flywheel, surprised the St100 worked at all!
I have also connected the St1000 to a garmin 152h GPS.
This is communicating perfectly, but i haven't done enough with it to tell yet how it performs.
Good luck.