ENGINE

An engine room will usually
contain multiple engines,
either diesel or heavy fuel.

The engine are used to provide
mechanical power to the gear
box which speeds up from the minimal
tickover, typically between 400-1000
rpm and a perates the ships hydraulic
pumps , and most importantly,
the screws or propellers.

In addition, it contains the generating
plan normally used to power the ships
electrics.

This often runs on separate engines,
with an array of smaller generators
contributing towards the ships
require power levels.

A margin of error will be allowed,
e.g. a ship requiring 300 amps
night employfour 90 amp generators


Taken from wikipedia