Magnetic interference from outboard on tiller pilot

erbster

erbster

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I am looking to install a tiller pilot on my 19' boat. I want to be able to use it when motoring, but my outboard generates a great deal of magnetic interference and would be inches from the tiller pilot.

The two models of tiller pilot I am considering are the simrad tp-10 or the raymarine st1000. I was considering a second hand simrad from fleabay, but I think will not work well with my outboard. Afaik, it cannot be connected to an external compass (which could be sited well away from interference).

It has been suggested to me that I could use self-adhesive lead sheeting on the inside of my outboard cover to suppress the interference. This would be a cheap and simple alternative, but would it work? Does the collective wisdom of the forum have any experience of this?:confused:

Ta.
 
erbster said:
I am looking to install a tiller pilot on my 19' boat. I want to be able to use it when motoring, but my outboard generates a great deal of magnetic interference and would be inches from the tiller pilot.

The two models of tiller pilot I am considering are the simrad tp-10 or the raymarine st1000. I was considering a second hand simrad from fleabay, but I think will not work well with my outboard. Afaik, it cannot be connected to an external compass (which could be sited well away from interference).

It has been suggested to me that I could use self-adhesive lead sheeting on the inside of my outboard cover to suppress the interference. This would be a cheap and simple alternative, but would it work? Does the collective wisdom of the forum have any experience of this?:confused:

Ta.
Click to expand...

Lead sheeting would have absolutely no effect on the magnetic field generated by your engine; for some reason this is a widely held belief that simply isn't correct. There was even a case where a fisherman got lost in poor visibility partly because he thought lead sheeting would be an effective way of screening his compass (there were other issues as well, but that was part of it). There is no way of shielding a magnetic field, except for total enclosure in an iron box, and that wouldn't be practical for an engine, and would shield the tiller-pilot from the earth's magnetic field!

If it was a static magnetic field, the tiller-pilot might be able to compensate for it by doing the usual calibration by turning circles. However, as I suspect the magnetic field will be varying according to engine revs etc., I doubt that would work.

The Raymarine unit can use an external compass sensor - I have an ST2000 that uses a compass sensor that feeds into the rest of the electronics. The sensor is mounted well away from any magnetic interference which is a good thing as I have a command mike for the VHF right next to the tiller-pilot, and that also causes errors in the built-in compass sensor.
 
How are you going to supply the power for the tp. anyway there would not be any interference when sailing. I presume that you are charging the battery from the o/b?
 
erbster said:
I am looking to install a tiller pilot on my 19' boat. I want to be able to use it when motoring, but my outboard generates a great deal of magnetic interference and would be inches from the tiller pilot.

The two models of tiller pilot I am considering are the simrad tp-10 or the raymarine st1000. I was considering a second hand simrad from fleabay, but I think will not work well with my outboard. Afaik, it cannot be connected to an external compass (which could be sited well away from interference).

It has been suggested to me that I could use self-adhesive lead sheeting on the inside of my outboard cover to suppress the interference. This would be a cheap and simple alternative, but would it work? Does the collective wisdom of the forum have any experience of this?:confused:

Ta.
Click to expand...

The magnetic field from the flywheel magnets will affect the TP compass even when the outboard is not running and the effect will vary according to the position in which it stops. It might even be worse than when its running

As Antarctic pilot says you cannot shield it with lead. It's good for shielding radioactivity and x rays but not effective against magnetic fields.
 
AntarcticPilot said:
Lead sheeting would have absolutely no effect on the magnetic field generated by your engine; for some reason this is a widely held belief that simply isn't correct. There was even a case where a fisherman got lost in poor visibility partly because he thought lead sheeting would be an effective way of screening his compass (there were other issues as well, but that was part of it). There is no way of shielding a magnetic field, except for total enclosure in an iron box, and that wouldn't be practical for an engine, and would shield the tiller-pilot from the earth's magnetic field!

If it was a static magnetic field, the tiller-pilot might be able to compensate for it by doing the usual calibration by turning circles. However, as I suspect the magnetic field will be varying according to engine revs etc., I doubt that would work.

The Raymarine unit can use an external compass sensor - I have an ST2000 that uses a compass sensor that feeds into the rest of the electronics. The sensor is mounted well away from any magnetic interference which is a good thing as I have a command mike for the VHF right next to the tiller-pilot, and that also causes errors in the built-in compass sensor.
Click to expand...

Thanks for the replies. Well, I was surprised but the person who told me about the lead shielding was insistent. I've held a compass
Next to my outboard and the needle jigs about all over the place. Was trying to avoid the expense of an external compass.
 
Sounds like you need the remote fluxgate compass, if that is an option.
It would be happier in the centre of the boat anyway, with less motion.
 
guernseyman said:
Sounds like you need the remote fluxgate compass, if that is an option.
It would be happier in the centre of the boat anyway, with less motion.
Click to expand...

My Seawych had a Yam 4hp and the Autohelm worked fine. It was fed off a battery that was charged off the boat as the ob had no charging circuit.
The same tp went on to have hissy fits two boats later with an inboard. The plots of circles to calibrate in Morecambe Bay were hilarious!
Try a friends?
 
NickRobinson said:
My Seawych had a Yam 4hp and the Autohelm worked fine. It was fed off a battery that was charged off the boat as the ob had no charging circuit.
The same tp went on to have hissy fits two boats later with an inboard. The plots of circles to calibrate in Morecambe Bay were hilarious!
Try a friends?
Click to expand...

My Autohelm works fine sailing or motoring with an Evinrude with battery charging.

I did once blow the voltage stabiliser circuit using it with the old Volvo outboard running without having the battery connected.
 
Like others I can only speculate on interference to the TP. As said onewould expect the interference to be worse when the o/b is stopped and then that depending on where the magnets in the flywheel end up. I would imagine the TP might be imune to the constantly varying magnetisme from the flywheel when motoring. However may be not.
If you already had the TP and it was suffering from interference I would suggest a piece of iron sheet mounted between the engine and the TP. Iron can be effective at shielding a magnetic field. I am not convinced that you would need a sealed box. However as you don't have a TP yet it seems like it will be a gamble as to risk buying a cheap TP which might or might not be useless due to interference versus buying one witha remote compass which will have no problems. Sorry not really any help olewill
 
I have an Raymarine ST1000 located near my outboard.
There is no doubt that the outboard affects the internal fluxgate compass. The effect on the compass depends on whether the motor is tilted or not and also whether it is running or not.
What i do is set the course according to the steering compass which is well away form both OB and Tiller pilot.
Basically i use the + and - buttons to get the boat on the course i want according to the steering compass or the mark 1 eyeball and disregard the compass display on the Tillerpilot.
Seems to work, and i assume deviation will be constant on a given course for a given motor status.(Tilted or not, running or not.)
You are still obliged to keep watch so you may as well watch your course according to the GPS and steering compass at the same time, so i dont see a big problem here.

When i get around to it i will interface with the chart plotter and be also able to steer for a waypoint. I assume that this will also bypass the Tiller pilot fluxgate compass?
Cheers
John
 
Thanks for the additional comments, folks. On my boat (a Cape Cutter 19), the outboard sits in a well in the cockpit directly under the tiller, so could hardly be closer to the tiller pilot. A number of fellow owners have TPs of both brands and all report that it is fine under sail. However, the problem seems to be with the Honda BF-5A, which seems to create a particularly large amount of magnetic interference, causing problems when motoring. One of my main motivations for getting a tp is when single handed to be to hold the boat head to wind when reefing, or putting out warps and fenders, as well as when on passage. I think I might look for a secondhand Raymarine, so that it is at least capable of being connected to an external compass and then see how I get on.
 
John the kiwi said:
I have an Raymarine ST1000 located near my outboard.
There is no doubt that the outboard affects the internal fluxgate compass. The effect on the compass depends on whether the motor is tilted or not and also whether it is running or not.
What i do is set the course according to the steering compass which is well away form both OB and Tiller pilot.
Basically i use the + and - buttons to get the boat on the course i want according to the steering compass or the mark 1 eyeball and disregard the compass display on the Tillerpilot.
Seems to work, and i assume deviation will be constant on a given course for a given motor status.(Tilted or not, running or not.)
You are still obliged to keep watch so you may as well watch your course according to the GPS and steering compass at the same time, so i dont see a big problem here.

When i get around to it i will interface with the chart plotter and be also able to steer for a waypoint. I assume that this will also bypass the Tiller pilot fluxgate compass?
Cheers
John
Click to expand...

We use an ST2000, with an internal gimballed fluxgate. It works OK most of the time. It is possible to recalibrate so it reads the same as your boat compass, but I just live with the occasional offset. We haven't wired in reverse from the chart plotter, so the steer to waypoint function has never been tested, though the NMEA input should work. ( I doubt I would trust that function anyway, as I prefer to keep a good watch...!!)
Mobile phones in crew or helm pockets can cause havoc - be warned.
I have seen the TP behave in a crazy manner due to magnetic rock anomalies in the seabed, where the steering compass did not respond so much- another external influence you have to live with occasionally.

It is more successful for motoring than sailing, and I would say it is least reliable on any kind of broad/deep reach, with a sea running. Those conditions are better with a human at the helm!
 
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