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The current scenario of possible configurations of propulsion for ships commercial or military is based on mechanical
mating between the main engine, which can be a diesel or gas turbine (GT) or a steam turbine, and the propellers through a
redaction gearbox and a shaft.
Diesel engines typically are used for medium-low speed, while the gas turbine is used to the top speed.
The main configurations of this type of propulsion, commonly called "mechanical drive", are:
CODOG = diesel or gas turbine combined
CODAG = Diesel and gas turbine combined
COGAG = Gas turbine and gas turbine combined
CODLOG = Diesel (electrical) and gas turbine combined
In recent years, there was widespread the use of electric propulsion configuration, especially on cruise ships, due to increased
demand for electricity for both propulsion and for uses of passengers accommodation. This configuration allows you to eliminate
the long lines of axis and obtain an improvement of the available space on board ship.
In this configuration, the main engine, typically a gas turbine, is coupled to an electric generator and propellers are coupled
to electric motors.
The spread of electric propulsion is expected to grow in the near future, not only for cruise ships but also warships, under the
excellent level of redundancy and low noise that characterize the electrical architecture. One example is the configuration CODLOG
adopted on FREMM frigates, which consist in a part of electric propulsion for the low speed and a mechanical propulsion for
the top speed.
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CODOG:
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CODAG:
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COGAG:
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CODLAG:
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