On land, the grid is (relatively) stable: 120V/60Hz in North America, 230V/50Hz in Europe. On a ship, however, generators are smaller, loads are more violent (radar pulses, gun drives, missile launchers), and fault conditions are extreme. Voltage sags, frequency wobbles, and harmonics are constant companions.
STANAG 1008 comprises several key components, including: stanag 1008
STANAG 1008 defines the nominal characteristics for shipboard electrical systems, specifically: On land, the grid is (relatively) stable: 120V/60Hz