Raymarine ST4000 Plus, Owner'S Handbook Manual

Page: 67 / 119

54 ST4000 Plus Wheel & Tiller Autopilots Owner’s Handbook
Note: A label is supplied to warn people that the compass is mounted
behind or below the bulkhead. This label should be attached where it
can be clearly seen.
Correct positioning of the fluxgate is crucial if ultimate autopilot
performance is to be achieved.
The fluxgate should, to minimise gimbal disturbance, be positioned as
near as possible to the pitch and roll centre of your boat.
ï It is important to ensure that the fluxgate compass is sited at least
0.8†m (2.5†ft) away from the steering compass to avoid deviation of
both compasses.
ï The fluxgate must also be positioned as far away as possible from
large iron masses, such as the engine and other magnetic devices,
which may cause deviation and reduce the sensitivity of the sensor.
ï If any doubt exists over magnetic suitability of the chosen site, the
position may be surveyed using a simple hand bearing compass. The
hand bearing compass should be fixed in the chosen position and the
vessel swung through 360∞.
ï Relative differences between the hand bearing compass and the
steering compass should ideally not exceed 20∞ on any heading.
Mounting location for steel-hulled vessels
If you have a steel-hulled vessel and mount the compass in the
conventional location, you will obtain significant deviation due to the
effects of steel on the Earthís magnetic field.
To minimise this effect, you should raise the compass transducer above
the main deck or wheelhouse. However, the higher above the waterline