MAIN ENGINE is INDEPENDENT; used ONLY for PROPULSION.
STEERING GEAR is LIKELY HYDRAULIC, with ELECTRIC MOTOR(s), powered by SHIPS SERVICE DIESEL GENERATOR(s), backed up by either a VITAL SERVICE GENERATOR and/or an EMERGENCY GENERATOR, with ability to be operated MANUALLY, AT THE STEERING GEAR ITSELF, with ORDERS given via SOUND POWERED PHONE.
When the POWER GOES OUT, it WILL cause loss of STEERING, but NOT loss of PROPULSION.