The liquid sulphertanker “Bearn” of the Societe Nationale Elf Aquitane was originally provided with one main propulsion engine. In view of the normal routes of the ship and the kind of cargo, the decision was taken not to rely on the diesel engine only but to convert the propulsion system into a CODOG (Combined Diesel Or Gasturbine) installation.

CODOG is not unknown, but mostly used on military or semi-military ships. These systems are designed for cruising on diesels for reasons of fuel economy and when higher power is needed the gasturbine is used. In this case the CODOG system is designed to ensure propulsion power in case of problems with the main engine. The problem with this installation was, that it had to be installed in an existing ship with very limited space available and no disturbance of the diesel engine propulsion system and ship’s construction was allowed.

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