For every
propeller shaft there is one
diesel engine for cruising speed and one
geared gas turbine for high speed dashes. Both are connected to the shaft with
clutches; only one system is driving the ship, in contrast to
combined diesel and gas (CODAG) systems that can use the combined power output of both. The advantage of CODOG is a simpler gearing compared to CODAG, but it needs either more powerful or additional gas turbines to achieve the same maximum power output. The disadvantage of CODOG is that the
fuel consumption at high speed is poor compared to CODAG. ==CODOG vessels==