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I have already talked about gas turbines in the past so this will be a short lesson today. Of the ship propulsion methods gas turbines are the newest kids on the block. The Royal Navy exterminated with gas turbine power in 1947. The first ship commissioned with gas turbines as their primary power source was in 1961, the Royal Navy’s Tribal Class frigates. The first ship in the US to be gas turbine powered was for the Coast Guard in 1967.

Gas turbines can be used for directly powering the ship, used to generate steam, or used with a diesel power source. Here is a list of the different types of systems that a gas turbine can be used in: CODOG, CODAG, CODLAG, COSAG, COGOG, COGAG, and COGAS. Here is how to decipher these. CO is combined, D is diesel, DL is diesel-electric, G is gas turbine, O is over, and A is and. So, CODOG is Combines Diesel over Gas Turbine. That means for each shaft diesel power is for normal cruising. A gas turbine engine is also available to be used for sprinting. When needed the clutches are engaged and the turbine adds its power to the shaft. The ship I was on was a COGAG, two turbines used for primary propulsion per shaft.

The main benefit of a gas turbine over a boiler system is a better HP to weight ratio and ease of repairs. More and more ships are being built with one of the above mentioned gas turbine systems.