Raymarin ST2000 and deviation

[Misil2]

I intend to buy a Raymarine ST 2000+ autopilot to my small sailingboat. It is independent and is not intended to be connected to other instruments.

I have identified that the place of placement has magnetic interference (loadspeakers). I realize that this will lead to the wrong course on the autopilot (deviation?). As I understand it, the deviation will vary depending on the course.

However, I will only use the autopilot for short periods. If I set a course with my other magnetic compass with the right rudder angle, can I lock the autopilot on this "wrong" course (according to autopilot) and trust that the course will be straight and correct according to the magnetic compass?

 

[john_morris_uk]

Yes and it’s exactly what we do. Our Raymarine autopilot compass rarely agrees with the ships main compass. I’ve swung the Raymarine one and gone all through its set up a couple of times but it makes no difference. I just put the boat on the right course by the main compass and press ‘auto’. I rarely bother to look at what the Raymarine Autopilot thinks it’s steering as I have total confidence in the main binnacle compass.

PS Sorry but I deleted your second attempt to post the same thing.

 

[Misil2]

Thanks for the reply. However, I get worried when I got this answer from Raymarine's help desk on the exact same question.

"Somehow, you've identified the issue: the proximity of the speaker will affect the reference heading store when you press AUTO and the calculation of the course deviation to make the correct ram movement to correct the course.

You pilot will not work close to a magnetic field."

Is there anyone who can sort out this question? I feel completely confused.

 

[RupertW]

Thanks for the reply. However, I get worried when I got this answer from Raymarine's help desk on the exact same question.

"Somehow, you've identified the issue: the proximity of the speaker will affect the reference heading store when you press AUTO and the calculation of the course deviation to make the correct ram movement to correct the course.

You pilot will not work close to a magnetic field."

Is there anyone who can sort out this question? I feel completely confused.

I agree with the post above and that’s how we have used all our autohelms and I never look at what it is saying and they will steer well for hundreds of miles at a time.

The sentence in bold is really saying that if it is so close to a magnetic field and so strong that the autohelm compass gets fixed to a particular reading now matter how the boat is pointing. If that is the case you do have an issue but in almost all cases if you swing the boat around you will see that the compass course does indeed change round the clock, but not necessarily at exactly the right rate - and that’s fine for all practical purposes unless the chart plotter is trying to control autopilot course changes.

 

[john_morris_uk]

Thanks for the reply. However, I get worried when I got this answer from Raymarine's help desk on the exact same question.

"Somehow, you've identified the issue: the proximity of the speaker will affect the reference heading store when you press AUTO and the calculation of the course deviation to make the correct ram movement to correct the course.

You pilot will not work close to a magnetic field."

Is there anyone who can sort out this question? I feel completely confused.

As Rupert says, what Raymarine are almost certainly saying is that if the autopilot fluxgate compass is so close to a magnetic field that it’s overwhelmed and can’t usefully detect the earth’s magnetic field then it won’t work. The advice to try and keep magnetic compasses (fluxgate or conventional) as far away from local influences is always true, but assuming you’re not mounting your autohelm compass on top of the speaker, the autopilot should still work. Just don’t take the course heading on the autopilot too seriously. Check your heading on the boats main compass (that’s presumably been swung and corrected!)

Remember that the official help desk will be a touch ‘risk averse’ in their ‘official’ advice. The real life solution is to try it and see.

 

[Misil2]

Hello guys Bear with me. What you write seems logical to my ears. But I want to be sure before I make this investment

I contacted Raymarine again for clarification. I basically asked if I could ignore the autopilot's compass.

I wrote: If I set a course of 90 degrees with the help of my magnetic main compass. If the autopilot shows 180 degrees when I turn it on auto. Will the boat keep the real course at 90 degrees with the help of the auto-pilot?

When I finish this distance, I put the autopilot on "standby". If I take a new magnetic course of 180 degrees, maybe the autopilot will show 160 degrees when I set it to "auto". Will the boat keep the real course at 180?

I got the following answer:

You have to understand that the real value of the heading does not matter for the autopilot, what I mean is that my you press AUTO the autopilot store whatever value that it used as a reference, putting a speaker next to the compass will probably "blind" the sensor and make wrong calculation of the course change. Most certainty, the autopilot will very quickly loose track of the boat's course change and the steering performance will be very poor.

Do anyone understand what he means? I get a feeling of beeing misunderstod.

 

[john_morris_uk]

Hello guys Bear with me. What you write seems logical to my ears. But I want to be sure before I make this investment

I contacted Raymarine again for clarification. I basically asked if I could ignore the autopilot's compass.

I wrote: If I set a course of 90 degrees with the help of my magnetic main compass. If the autopilot shows 180 degrees when I turn it on auto. Will the boat keep the real course at 90 degrees with the help of the auto-pilot?

When I finish this distance, I put the autopilot on "standby". If I take a new magnetic course of 180 degrees, maybe the autopilot will show 160 degrees when I set it to "auto". Will the boat keep the real course at 180?

I got the following answer:

You have to understand that the real value of the heading does not matter for the autopilot, what I mean is that my you press AUTO the autopilot store whatever value that it used as a reference, putting a speaker next to the compass will probably "blind" the sensor and make wrong calculation of the course change. Most certainty, the autopilot will very quickly loose track of the boat's course change and the steering performance will be very poor.

Do anyone understand what he means? I get a feeling of beeing misunderstod.

I think they’ve just written another version of what I wrote.
If you put the speaker really close the autopilot won’t work.

 

[AntarcticPilot]

Agree with all of the above; if the tiller pilot is in a strong magnetic field, it won't be able to compensate for it and so won't hold a course. I had that problem with the command mike for my VHF, which is near the tiller pilot. Because my instruments are integrated, I had to install a separate fluxgate compass mounted in a location well away from anything magnetic - when the tiller pilot was not attached to the tiller, I was getting extremely misleading heading information in the system! The separate compass over-rides the internal compass, so that was a robust fix.
The other point is that depending on your speaker, it is possible that the strength of the magnetic field could vary according to whether the speaker is powered or not.

 

[Misil2]

Thanks all.

1. is there any possibility to determine if magnetic interference is too great for an installation if the boat is on land?

I have tested with a hand compass and it does not seem to be too much of a deviation.

2. if there is too much deviation, I can solve it with an external fluxgate compass without connecting it to other instruments. Do you have suggestions for a cheap solution?

 

[Iliade]

Put your hand bearing compass where you plan to mount the TP base socke, sail the boat in a circle and watch the compass. If it goes round with little or no disturbance all should be fine; If it points determinedly in one direction you need to move the speakers.

 

[Misil2]

It is not possible to do it on land?

 

[AntarcticPilot]

It is not possible to do it on land?

No - you need to be able to vary the orientation of the complete system with respect to the Earth's magnetic field. So, you need to have the tiller-pilot in its operating position, and turn the entire boat.

What you're investigating is whether the compass simply exhibits a large deviation from the influence of the external magnetic field (which might be able to be compensated for) or whether the external magnetic field completely overwhelms the Earth's magnetic field so the compass only moves through a small arc rather than the full circle as the boat's heading changes.

Given the strength of modern magnets, the latter is a very real possibility, and the only solutions are either to move the speakers or to install a remote compass sensor. The considerably less powerful magnets of a command mike messed up my tiller-pilot; though in that case the effect was compunded by the mike not being fixed.

I can't think of a way of testing it without being able to rotate the entire boat; you need to be able to maintain the geometric relationship between the compass sensor and the speaker while altering heading. Most fluxgate compasses automagically self-correct for external effects by being steered in a circle a few times.

 

[Buck Turgidson]

Move the speaker.
To be honest I would ask how close is the speaker to the tiller pilot? Does the speaker need to be on?

Great boat by the way "Misil2" I thought about getting one a few years ago but couldn't find one near by.

 

[Misil2]

Thanks everyone for the help. It is much appreciated. It's starting to be time to finish the project of a possible installation a raymarine st2000. I enclose a picture of the placement area.

According to the instructions, the pilot should be placed about 10 centimeters behind the low-magnet speakers. The pilot is placed on the rim and tiller, ie a few centimeters above the speaker.

If I have calculated correctly, the fluxgate compass itself is about 40-50 cements from the speaker on the starboard side. With the help of an app that measures the magnetic field, the value is about 45-55 uT in the area affected. Surprisingly, it is not slightly higher than other areas in the boat.

Is it possible to determine from these calculations whether the fluxgate compass will work?

 

[Misil2]

Addition to previous post.
References I have found about magnetic felds.

"In general finding a location with fewer than 75 uT (micro-Teslas) can be accommodated by onboard calibration of the Pelagic compass".

Speaker to magnets

 

[Buck Turgidson]

Thanks everyone for the help. It is much appreciated. It's starting to be time to finish the project of a possible installation a raymarine st2000. I enclose a picture of the placement area.

According to the instructions, the pilot should be placed about 10 centimeters behind the low-magnet speakers. The pilot is placed on the rim and tiller, ie a few centimeters above the speaker.

If I have calculated correctly, the fluxgate compass itself is about 40-50 cements from the speaker on the starboard side. With the help of an app that measures the magnetic field, the value is about 45-55 uT in the area affected. Surprisingly, it is not slightly higher than other areas in the boat.

Is it possible to determine from these calculations whether the fluxgate compass will work?

are your measurements with the speaker on?

 

[Misil2]

No.

 

[john_morris_uk]

I can see your potential problem. Those speakers are in exactly the wrong place.
Have you thought of upgrading your autopilot to one with a remote compass and course computer?
eg EV-100 Tiller | Raymarine Evolution Autopilot

We used to have an earlier version on our Sigma 33 and it was vastly superior to the entirely self contained autopilot.

 

[GHA]

If I have calculated correctly, the fluxgate compass itself is about 40-50 cements from the speaker on the starboard side. With the help of an app that measures the magnetic field, the value is about 45-55 uT in the area affected. Surprisingly, it is not slightly higher than other areas in the boat.

Is it possible to determine from these calculations whether the fluxgate compass will work?

I have removable speakers about 50cm from the main compass, all that happened after first use was that they cancelled out the 5deg variation. Though varied a bit with different points of sail. Very likely you'll be OK, tiller pilot isn't going to give you a perfect course anyway but point and click should be plenty good enough.

Edit - also, know anyone nearby with a tiller pilot you could borrow? Lay it out on a board or something with a speaker and spin the board to see just what happens in the real world, might be more productive than getting lots of contradictory forum guesswork.

 

[doug748]

Buy the Autohelm and see how you get on, if you have problems fit these:

Pair of Waterproof Non-Magnetic Speakers - White | Float Your Boat

.