The ideal position is as close as possible to the pitch and roll centre of the boat.

On a sailing boat this often conflicts with the position of other equipment and may also be subject to interference from the iron keel/ ballast. The handbook offers many suggestions, but in principle, move the fluxgate aft and outboard until a position is found which has minimal deviation. This position should also be checked with a hand bearing compass, for sources of hidden deviation. Often positions 3-4 feet off the centreline and 2-3 feet above the waterline will give excellent performance.
On a power boat, the ideal position often ends up between the engines, so it is important to relocate the fluxgate. Since height has a much better effect at reducing deviation, the sensor can be raised to a position 3 feet or more above the top of the engines, alternatively move it aft - unless the boat has I/O drives in which case keep the sensor at least 4 feet forward of the engine room!

Do not mount the compass in the front 1/3 of the boat due to shock motion and whilst lead shielding works well for Kryptonite, it has no effect on shielding the sensor from magnetic interference!

If in any doubt, mount the compass temporarily with tape and carry out a linearisation swing, be prepared to move it if necessary
 
 

No, most definitely not. All Autohelm equipment containing a fluxgate compass will rattle when shaken, as the compass unit is mounted internally on gimbals. The sound is that of a rubber buffer hitting the inside of the case and from our point of view, it's a reassuringly good sound!
 
 
 

When an autopilot compass leaves the company, it has no idea where it is going. This means that it needs to be set up by its new owner. There are two parts to a compass linearisation:

1.Linearisation
This operation removes the influence of metallic/magnetic objects situated close to the fluxgate compass. To do this, the vessel must be turned slowly through 720 degrees while the compass is in calibration / automatic linearisation mode (a 2 second hold down of the standby key).

2.Compass Alignment
After linearisation the compass should be aligned to a known heading. Steer the vessel on a constant bearing (transit line is ideal) and use the + and - course change buttons to correct the reading accordingly.