First of all it must be understand that any current carrying conductor always sets up a magnetic field around it. Secondly whenever there is potential difference an electric field extends into its vicinity.
if for any equipment its electric field interfere with other equipments electric field it will results in malfunction.
Electromagnetic compatibility is defied as the ability of all equipment i.e electrical,electronic and mechanical to work together without accidental electrical coupling between them thereby causing any malfunction
SOLAS requirement of EMC:
1 Administrations shall ensure that all electrical and electronic equipment on the bridge or in the vicinity of the bridge, on ships constructed on or after 1 July 2002, is tested for electromagnetic compatibility taking into account the recommendations developed by the Organization.
2 Electrical and electronic equipment shall be so installed that electromagnetic interference does not
affect the proper function of navigational systems and equipment.
3 Portable electrical and electronic equipment shall not be operated on the bridge if it may affect the
proper function of navigational systems and equipment.