St4000 - wiring and voltage drop

[Chuck - Raymarine - Moderator]

James,

Deviation is the effect of the magnetic field generated by the vessel or by objects witin the vessel upon a magnetic compass. Objects which have magnetic fields associated with them include objects constructed from ferrous materials, magnets, electrical coils, or those that consume or carry high current loads. The fluxgate compass should not be installed within three feet of such objects. In some vessels, particularly steel hulls, the fluxgate will be installed above deck (ex. on the mast, pole, etc.). The sensed deviation may differ based upon heading and as such vessels will "swing the compass" (a procedure by which the vessel will be steered slowly in a circle to determine the amount of deviation at various sample points of the compass. For this generation of autopilots, the installation location for the fluxgate should ideally sense a maximum deviation which is less than ten degrees. Excessive deviation sensed by the fluxgate compass may adversely affect the performance of an autopilot.