Tiller pilot mounted near outboard motor in a cockpit well - compass issues?

[Petertheking1982]

I had an st2000 on an achile's 24 with motor in well directly under the tiller. It would be fine if motor off, but went haywire if the motor was running. I ended up going the external compass route (if your brave / skint you can remove internal compass and solder on extension lead!). I think main problem with my motor was the magneto charging coil which was a big ring of magnets on top of the engine.

 

[chris-s]

Previous Pegasus 700 with an outboard in a well and tiller pilot running over it, definite interference tho we found that if you left the revs alone it would settle out, but then go haywire for a while when you adjust the throttle.

 

[Refueler]

Thank you for this! I haven't yet explored the idea of having a remote compass, connected to the tiller unit by NMEA or similar. The ST1000 may be able to operate this way, as it has a data connection. The TP10 has no data connection, though the larger TP20 & TP30 apparently have one. And I think I had an Autohelm 2000 (?) back in the 1980s, that had a control unit connected to the tiller actuator by a cable.

[/QUOTE]
The 2000 would have been ideal for this ... I have one on my 38 .... didn't like it at first - so used my later 1000 ... but then tried it again and I actually like it.

I imagine modern autopilots have fluxgate compasses, mounted on the internal printed circuit board.

I appreciate your thoughts about magnetic objects 'stalling' the compass.[/quote

Maybe - I haven't opened a current model but most I've seen have similar separate fluxgate as the old 100's etc.

It doesn't take much to do it ... its trying to work with earths magnetic field ....

I'm not hugely worried about the accuracy of the compass in the autopilot - I can always check it against the boat's main compass. I'd just like it to be able to maintain a heading, more-or-less.
I'm not particularly interested in waypoint turns either, I'm happy to do that stuff manually.

- Geoff

The reading on a later pilot - unless its mounted in a really good position with literally no interference - then you could compare with main compass - but most are under some influence so I would not rely on it or consider it indicating actual heading ....

No Tiller pilot I know of makes waypoint turns without first plotter giving alarm as approaching WP ... user then accepts that plotter can direct pilot to next WP. Even ships cannot do it without OOW accepting the course change.

 

[LittleSister]

. . . the recommeded attachment position (the pin) for the ST1000+ (Raymarine) and the TP10 (Simrad) is 18" from the rudder pivot, which is right over the motor.

Strictly speaking it is 18" measured perpendicular to the rudder pivot axis (including an extension of that axis if need be). If your rudder pivot is not vertical by any significant amount (as is the case on some boat designs) this will give a different length along a horizontal tiller from the pivot, and likewise if the rudder pivot is vertical, but the tiller significantly different from horizontal.

Note also that the tillerpilot should be mounted so that it is horizontal when in operation, and not angled up or down towards the tiller. Raymarine sell a range of fittings (albeit at a 'marine kit' price) to either raise the socket on the coaming (or whatever) that the tiller pilot fits into; or to raise or lower the 'pin' on the tiller that the tiler pilot fits into. I suspect Navico also sells such fittings, but also believe the two brands' fittings are interchangeable because the mounting pins and sockets dimensionally identical.

PS. For efficient Tillerpilot operation the ram stroke should be VERY close to center when the tiller is centered. When I bought my boat the cockpit pin socket was fitted the only place it could be. But I was never really satisfied with the operation. I measured and found it was 40 mm off center stroke. Made up a jig the relocated the pin socket so the ram was centered and it was the world of difference. In my view 20mm off center is the max.

I agree it is important to have a tiller pilot mounted with the centre of its stroke with the tiller centred, giving a full half-stroke of the ram in either direction, otherwise the autopilot will too often not be able to recover when the boat yaws too far off the intended heading in one direction.

But you do not need necessarily need to rig up a jig to achieve this. Raymarine will sell you (at a price!) ram extensions of various lengths to achieve, near enough, the the end of the extended and retracted ram being equal either side of the boat's centreline. As above, It is likely that Navico also sell such fittings, but I believe the ram diameter and the thread inside the ram end are the same in both brands, so that those parts are interchangeable between brands.


Now back to the original electrical interference problem!

1 - I am assuming that the interference is magnetic, rather than with the power supply to the tillerpilot (by e.g. an insufficiently smoothed 'charging' electrical output from the motor to the shop's battery).

2 - Can the more knowledgeable among you advise whether fitting an earthed plate under the tillerpilot might provide a degree of shielding of it from the magnetic interference from the motor below?

3 - You could perhaps mount the tillerpilot elsewhere, with a bit of 'traditional PBO' jiggery-pokery. Because of layout challenges on my own boat (unrelated to electrical interference) I've pondered, but not yet tried:
(a) mounting the tillerpilot along the length of the boat, with it acting on a supplementary 'tiller', 18" long, and at right angles to the original tiller.
(b) attaching a continuous line to the ram end, line run across the cockpit using small blocks, and using tiller mate-type clamp under the tiller to attach/detach the tiller to/from the line at the pre-marked 'centralised' point.
(c) I have a neater, more elaborate and too-complicated-to-explain-here plan for the slightly unusual set up in my own boat, which has a latching/unlatching quadrant on the rudder shaft below the aft deck, by which the boat can currently be steered by a wheel in a wheelhouse (the tiller also moves but can be left in place or quickly removed), or the connection to the wheel detached when steering by tiller in the cockpit (making for lighter, faster tiller movements).


Good luck!

 

[thinwater]

Strictly speaking it is 18" measured perpendicular to the rudder pivot axis (including an extension of that axis if need be). If your rudder pivot is not vertical by any significant amount (as is the case on some boat designs) this will give a different length along a horizontal tiller from the pivot, and likewise if the rudder pivot is vertical, but the tiller significantly different from horizontal.

Yes, of course. I truncated my description because this is a forum. The instruction are in the manual.

Note also that the tillerpilot should be mounted so that it is horizontal when in operation, and not angled up or down towards the tiller. Raymarine sell a range of fittings (albeit at a 'marine kit' price) to either raise the socket on the coaming (or whatever) that the tiller pilot fits into; or to raise or lower the 'pin' on the tiller that the tiler pilot fits into. I suspect Navico also sells such fittings, but also believe the two brands' fittings are interchangeable because the mounting pins and sockets dimensionally identical.

I agree it is important to have a tiller pilot mounted with the centre of its stroke with the tiller centred, giving a full half-stroke of the ram in either direction, otherwise the autopilot will too often not be able to recover when the boat yaws too far off the intended heading in one direction.

But you do not need necessarily need to rig up a jig to achieve this. Raymarine will sell you (at a price!) ram extensions of various lengths to achieve, near enough, the the end of the extended and retracted ram being equal either side of the boat's centreline. As above, It is likely that Navico also sell such fittings, but I believe the ram diameter and the thread inside the ram end are the same in both brands, so that those parts are interchangeable between brands.


Now back to the original electrical interference problem!

1 - I am assuming that the interference is magnetic, rather than with the power supply to the tillerpilot (by e.g. an insufficiently smoothed 'charging' electrical output from the motor to the shop's battery).

2 - Can the more knowledgeable among you advise whether fitting an earthed plate under the tillerpilot might provide a degree of shielding of it from the magnetic interference from the motor below?

3 - You could perhaps mount the tillerpilot elsewhere, with a bit of 'traditional PBO' jiggery-pokery. Because of layout challenges on my own boat (unrelated to electrical interference) I've pondered, but not yet tried:
(a) mounting the tillerpilot along the length of the boat, with it acting on a supplementary 'tiller', 18" long, and at right angles to the original tiller.

Or 14-16 inches long. Better for a smaller boat.

(b) attaching a continuous line to the ram end, line run across the cockpit using small blocks, and using tiller mate-type clamp under the tiller to attach/detach the tiller to/from the line at the pre-marked 'centralised' point.
(c) I have a neater, more elaborate and too-complicated-to-explain-here plan for the slightly unusual set up in my own boat, which has a latching/unlatching quadrant on the rudder shaft below the aft deck, by which the boat can currently be steered by a wheel in a wheelhouse (the tiller also moves but can be left in place or quickly removed), or the connection to the wheel detached when steering by tiller in the cockpit (making for lighter, faster tiller movements).


Good luck!

Like any autopilot, it needs to be tuned to the boat. One of the limitations with tiller pilots, particularly at the 18" setting, is that the tiller range of motion (+/- 16 degrees) is far less than the 25 degrees or so commonly used during tacking. Installing it at 14 inches increases this to 21 degrees, as well as hastening the motion.

It's a smaller boat tuning issue.

 

[MontyMariner]

You can check the ob's magnetic field by looking at the deflection using a hand bearing compass and moving it around the ob when running.

 

[LittleSister]

Yes, of course. I truncated my description because this is a forum. The instruction are in the manual.

Or 14-16 inches long. Better for a smaller boat.

Like any autopilot, it needs to be tuned to the boat. One of the limitations with tiller pilots, particularly at the 18" setting, is that the tiller range of motion (+/- 16 degrees) is far less than the 25 degrees or so commonly used during tacking. Installing it at 14 inches increases this to 21 degrees, as well as hastening the motion.

It's a smaller boat tuning issue.

I see the point, but only likely to be feasible on either a smaller, lighter boat, or with a higher cost model tillerpilot than the normal recommendations. Otherwise tillerpilot likely to be overwhelmed or overworked.

Ensuring the rig is balanced may avoid the need to reject the manufacturer's recommendations.

 

[thinwater]

I see the point, but only likely to be feasible on either a smaller, lighter boat, or with a higher cost model tillerpilot than the normal recommendations. Otherwise tillerpilot likely to be overwhelmed or overworked.

Ensuring the rig is balanced may avoid the need to reject the manufacturer's recommendations.

In my case my F-24 is ~ 1500 pounds and has VERY light helm. Two fingers is nearly always enough. And I prefer the TP2000 for it's speed, which also provides greater force. It's a better unit.

Yes, only smaller boats. That is the point. A heavier boat probably does not need the greater helm angle and quicker response; they don't stall when tacking as easily. And of course, proper rig balancing is basic and vital to the performance of any autopilot. If the boat is yawing you are working it to death. Don't ask it to do what would tire you. Off the wind reef the main first.

 

[garymalmgren]

Morning Geoff
A bit of miscommunication here,

RE: Thanks for the info about compass locations being much the same in the two tillerpilots. It seems like the logical place for it to be, near the pivot pin (mounting end), rather than at the end where the tiller arm comes out of the housing.

The fluxgate compass on both models is actually mounted at the end where the ram leaves the plastic casing. This locates them as far from the internal drive motor as possible, but very close to the printed circuit boards.

 

[Chris_Burns]

Hello Geoff,

I have a 20' Red Fox RF200E which has a central outboard well, so a similar arrangement to your Baroness. For nearly 20 years I used either an ST1000+ or (later) ST2000+ without any problem….. But last year I changed the original series A Tohatsu 6 sailpro for a series D model and had significant auto-pilot problems.

The symptoms when sailing were tacking through abnormal angles when using the auto-tack and very "wobbly" course holding when motoring.

To begin with I thought that my AP had perhaps lost compass calibration over the winter but further investigation showed that it was actually the new outboard that was the cause of the problem.

To test, I set the autopilot to show the heading whilst tied up on the pontoon with outboard not running. I then very slowly pulled the starter cord to rotate the flywheel and found that the compass heading shown on the AP changed considerably. With the motor running the indicated heading was erratic.

When I examined the two outboards further I found that the A series has a good cast metal cover over the top of the flywheel, whereas the new D series cover is made of plastic. The difference in magnetic shielding was enough to make the AP unusable.

So my point is the model of outboard may be significant to the ability of your AP to operate when mounted close to the outboard, especially if the outboard has a charging coil and flywheel magnet.

In my case it prompted me to undertake a project to remove the fluxgate compass and control board from the main AP body and to mount them separately in dry locations. It got quite involved but if anyone is interested I can post further information and photos on how I did this, and the 3D printed mounts I used to fit limit switches to protect against the well-known problem of the ST units stripping drive belts/gears when hitting the end-stop buffers.

Regards

Chris.

 

[GeoffDDDD]

I had an st2000 on an achile's 24 with motor in well directly under the tiller. It would be fine if motor off, but went haywire if the motor was running. I ended up going the external compass route (if your brave / skint you can remove internal compass and solder on extension lead!). I think main problem with my motor was the magneto charging coil which was a big ring of magnets on top of the engine.

Hi Petertheking,
Thank you very much for this info.
That is very clear, that the physical motor is not the problem, the problem is when it is running.
As you point out, that may well be the battery charging. Though it could also be the ignition system.
I'd been considering connecting an external compass via the NMEA or the other data port. But very expensive.
I love your solution, to remove the compass and mount it elsewhere with an extension lead.
Did that fix the problem? Completely?
Did you need to use screened cable for the extension lead? Twisted pair?
I'd love to hear more about your solution.
Best wishes - Geoff

 

[GeoffDDDD]

Morning Geoff
A bit of miscommunication here,

RE: Thanks for the info about compass locations being much the same in the two tillerpilots. It seems like the logical place for it to be, near the pivot pin (mounting end), rather than at the end where the tiller arm comes out of the housing.

The fluxgate compass on both models is actually mounted at the end where the ram leaves the plastic casing. This locates them as far from the internal drive motor as possible, but very close to the printed circuit boards.

Aaaah, my apology. Thank you for clarifying. Of course, locating the compass as far as possible from the autopilot drive motor makes sense.
I'm not familiar with the innards of a tiller pilot - as you can tell!
Thanks again - Geoff

 

[GeoffDDDD]

Previous Pegasus 700 with an outboard in a well and tiller pilot running over it, definite interference tho we found that if you left the revs alone it would settle out, but then go haywire for a while when you adjust the throttle.

Hi chris-s,
Thank you for this info.
Clearly a problem with the tiller pilot over the outboard. At times anyway.
A bit mystifying about the effect of changing the revs. Any thoughts or impressions why this occurred?
- Geoff

 

[Refueler]

Hi chris-s,
Thank you for this info.
Clearly a problem with the tiller pilot over the outboard. At times anyway.
A bit mystifying about the effect of changing the revs. Any thoughts or impressions why this occurred?
- Geoff

Think about your outboard and its magneto / ignition / coil ... as you change throttle - that lot alters its output. Outboards do not have alternators in the small sizes .. so the output varies with RPM. Plus those magnets are whizzing round at different speeds based on RPM.

 

[GeoffDDDD]

Hello Geoff,

I have a 20' Red Fox RF200E which has a central outboard well, so a similar arrangement to your Baroness. For nearly 20 years I used either an ST1000+ or (later) ST2000+ without any problem….. But last year I changed the original series A Tohatsu 6 sailpro for a series D model and had significant auto-pilot problems.

The symptoms when sailing were tacking through abnormal angles when using the auto-tack and very "wobbly" course holding when motoring.

To begin with I thought that my AP had perhaps lost compass calibration over the winter but further investigation showed that it was actually the new outboard that was the cause of the problem.

To test, I set the autopilot to show the heading whilst tied up on the pontoon with outboard not running. I then very slowly pulled the starter cord to rotate the flywheel and found that the compass heading shown on the AP changed considerably. With the motor running the indicated heading was erratic.

When I examined the two outboards further I found that the A series has a good cast metal cover over the top of the flywheel, whereas the new D series cover is made of plastic. The difference in magnetic shielding was enough to make the AP unusable.

So my point is the model of outboard may be significant to the ability of your AP to operate when mounted close to the outboard, especially if the outboard has a charging coil and flywheel magnet.

In my case it prompted me to undertake a project to remove the fluxgate compass and control board from the main AP body and to mount them separately in dry locations. It got quite involved but if anyone is interested I can post further information and photos on how I did this, and the 3D printed mounts I used to fit limit switches to protect against the well-known problem of the ST units stripping drive belts/gears when hitting the end-stop buffers.

Regards

Chris.

Hi Chris_Burns,

Thank you very much for your informative post.

Your tests tied to the pontoon are very interesting. If I may interpret them, it seems that the flywheel position, even with the motor not running, makes a major difference to the compass reading. Not entirely surprising of course, given there are magnets in the flywheel, but good to get the confirmation.

The erratic reading with the motor running seems to say the rotating flywheel doesn't somehow "average out" its magnetic influence. I don't know how a fluxgate compass is used in an autopilot, but I'm wondering whether it just takes an instantaneous reading, maybe a few times a second -- if so, you might get several readings with similar flywheel positions, then several with quite another position. Just speculating here, of course.

Your comment about the different flywheel covers in series A vs series D makes lots of sense. I wonder whether adding a soft iron shield to the series D motor might have fixed the autopilot issue. Not pretty of course, unless you were able to fit it inside the motor's outer cover.

I'm very interested in your project to remote mount the fluxgate compass. It sounds like you and Petertheking1982 had the same idea! I'm assuming it was successful in your case? So yes, I'd appreciate photos and more information. And so might many others...

Also, I suspect quite a few people would be interested in your limit switch modification to the ST autopilots. But I guess that would deserve its own thread on the forum.

Thank you so much for sharing this info - Geoff