Fluxgate compass;- where to site.

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Graham_Wright

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Gloucestershire
www.mastaclimba.com
The recommended location is near the centre of rotation of the boat, not less than 1m from metallic components, dry, safe from knocks etc, etc etc.

Seems to rule out everywhere on my fit.

What have forum members got away with breaking the above rules?
 
Mine is on the bulkhead (the one that goes between the shroud plates), under the saloon settee.
 
Graham_Wright said:
The recommended location is near the centre of rotation of the boat, not less than 1m from metallic components, dry, safe from knocks etc, etc etc.

Seems to rule out everywhere on my fit.

What have forum members got away with breaking the above rules?
Click to expand...

I mounted mine (Raymarine SPX5 Autopilot) on the forward leg of the saloon table. It is obviously too close to the keels as there is quite a bit of error on it, 5 or 6 degrees on most headings. I raised it as far as I could under the table and it improved, but I'm still not happy with it. I have spoken to another Fulmar owner and his is mounted in the hanging locker on the bulkhead that divides the saloon and forward cabin. It is off the centre line of the boat but much higher than mine is mounted. He is happy with his, so its one of the jobs planned for this winter to re-route the cabling and try it there.
 
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Wherever you put it, it's a compromise. Mine is in a hanging locker in the fwd cabin, and it works OK.
 
In a hanging locker in the aft cabin. Previously in the lazarette. Worked in both cases (same boat). Deviation well within capability of the autocorrection.
 
I have a couple, one for the autohelm which lives in a hanging locker about a quarter of the way up the boat from the stern. It works fine but have to be careful not to put oily jackets with heavy metal harness clips next to it. The other one is a quite expensive (£750ish) stand alone one that is connected to the plotter. That lives in a locker close to the Vhf and a marine stereo, again not near the midships. It seems very forgiving and is always within a degree or two of the steering compass that I know is accurate.

Is there anywhere under the cabin sole where you could mount it. I made a bracket for it there on Saumur and again it worked well.
 
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I am sure that mine is within a metre of a three ton iron keel, but it still seems to work. It is in an under seat locker, just below seat level, at the front of the saloon, and about 18 inches to starboard of the centre line
 
I mounted mine inside the saloon table, which has a bottle locker in the middle, at the forward end. It's quite close to the mast support pillar but that's stainless so I assume non-magnetic. It seems reasonably happy there but I did notice a significant deviation just recently, but it now has a tubular heater alongside the table so I am assuming that's the cause. It was previously mounted under the starboard settee on the bulkhead which has the chart table on the other side, with the cabling for the plotter, radar and radio close by, it did not like that at all!
 
Graham_Wright said:
The recommended location is near the centre of rotation of the boat, not less than 1m from metallic components, dry, safe from knocks etc, etc etc.

Seems to rule out everywhere on my fit.

What have forum members got away with breaking the above rules?
Click to expand...
Mine is under the hanging locker sole just forrard of the main bulkhd, its 800m/m off the C/L, my keel is 3 tons of lead
 
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The original, Raymarine, on my last boat was in stbd, aft hanging locker. The replacement, Lowrance, was under a seat stowage in the main saloon. No idea where the one on my new boat is as I haven't found where they've hidden it yet :)
 
Mine is on an internal partition of the locker we use for food and drink stowage. This is a crappy location, as I discovered when my dad stowed a dozen steel cans of beer right next to it. The autopilot performed so badly that my mate didn't believe we had one fitted.

During this winter I plan to move it to the saloon table leg, where there's nothing metallic too near by.

Pete
 
Flux gate sensor location

I would think important things to avoid mounting it near an iron keel, engine, anything with a loud speaker in anything with a small motor or moving pointer electrical meter.
The latter things having a magnet inside. You could try checking with a hand bearng compass for any deviation. If possible avoid stowge places as people can stow iron objects or earphones with magnets. I am not sure how important it is to have it near the centre of rotation and pitch of the boat. good luck olewill
 
Mine is below the saloon floor on a transverse stringer. Unfortunately it is between the two bilge keels which, allegedly, contain iron. The control unit shows a large deviation. The manual says this happens on steel-hulled boats. But it holds a course fine, just not the one it says.
 
guernseyman said:
Mine is below the saloon floor on a transverse stringer. Unfortunately it is between the two bilge keels which, allegedly, contain iron. The control unit shows a large deviation. The manual says this happens on steel-hulled boats. But it holds a course fine, just not the one it says.
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Similar but lead keel and works very well. This is middle is saloon floor so not effected by anything magnetic
 
Thanks for all the responses. I have a very substantial mast support pillar 150 x 100 but it is stainless.

I'll try attaching it to that. I don't know what grade the pillar is but I'll see if it affects the hand bearing compass first.
 
Graham_Wright said:
The recommended location is near the centre of rotation of the boat, not less than 1m from metallic components, dry, safe from knocks etc, etc etc.

Seems to rule out everywhere on my fit.

What have forum members got away with breaking the above rules?
Click to expand...

IIRC, the older 63' BT Challenge yachts, all steel boats, had their fluxgate compass mounted above deck either on/near the mast.

No auto helm on these, hand steering all the way.
 
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