This article was accepted into the corpus but its outbound wikilinks were never NER-processed — typical at the deepest BFS hop or when the run's entity cap was reached. No expansion funnel to show.
| Combined Diesel or Gas | |
|---|---|
| Name | Combined Diesel or Gas |
| Acronym | CODOG |
| Type | Marine propulsion system |
| First use | 20th century |
| Primary users | Navies and commercial shipbuilders |
Combined Diesel or Gas.
Combined Diesel or Gas is a marine propulsion arrangement that pairs Diesel engines with Gas turbines to drive a vessel's propellers, allowing ships to switch between powerplants for efficiency or speed. Developed for naval warfare applications and adopted by commercial shipping firms, the system has been installed on classes such as the Type 22 frigate, Oliver Hazard Perry-class frigate, HMS Sheffield (F96), and FREMM-class vessels. Designers and shipyards including Vickers Shipbuilding, Bath Iron Works, DCNS, Blohm+Voss, and Chantiers de l'Atlantique integrated CODOG into projects alongside manufacturers like General Electric, Rolls-Royce, MTU Friedrichshafen, and MAN SE.
CODOG combines the fuel economy of MAN B&W or Sulzer diesel engines for cruising with the high power density of GE LM2500 or Rolls-Royce Olympus gas turbines for sprinting, using clutches and gearboxes to select the active prime mover. The propulsion train typically includes a reduction gearbox, controllable-pitch propeller systems from suppliers such as Kamewa or Schottel, and shaft lines developed by firms like Shaftline Engineering and Liebherr. Control architectures integrate automation from vendors like ABB and Siemens to manage load sharing, vibration damping, and transition sequences influenced by standards from organizations such as ISO and Lloyd's Register.
Variants include CODOG alongside related schemes like CODAG, COGAG, CODLAG, and COGOG, and hybridized forms combining electric drive elements from companies like Siemens and Rolls-Royce MTU. Configurations differ in gearbox complexity (single-shaft vs. twin-shaft), propulsor type (fixed-pitch vs. controllable-pitch propeller), and auxiliary systems such as electric drive integration on vessels like HMS Daring (D32) or the Zumwalt-class destroyer. Ship classes demonstrating different configurations include the Type 23 frigate, D'Estienne d'Orves-class aviso, and Jakarta-class corvette.
Navies including the Royal Navy, United States Navy, Royal Australian Navy, German Navy, Italian Navy, and Japanese Maritime Self-Defense Force employed CODOG in frigates, corvettes, and patrol vessels. Commercial operators and coast guard services such as the United States Coast Guard, Canadian Coast Guard, and Australian Border Force used similar principles in high-speed cutters and offshore patrol vessels derived from designs by Bollinger Shipyards, Austal, and Fincantieri. CODOG also appeared in research and survey vessels commissioned by institutions like Scripps Institution of Oceanography and Woods Hole Oceanographic Institution.
Advantages include fuel-efficient cruising afforded by diesel engines, rapid acceleration from gas turbines for tactical maneuvers in scenarios like anti-surface warfare or anti-submarine warfare, and reduced machinery footprint compared with entirely diesel or turbine setups. Limitations involve gearbox complexity that drew scrutiny from inspectors at Bureau Veritas and Det Norske Veritas, acoustic signatures relevant to ASW considerations, maintenance burdens tied to vendors like MTU Friedrichshafen and GE Marine and logistical chains exemplified by Naval Supply Systems Command. Cost considerations influenced procurement decisions in programs such as National Shipbuilding Procurement Strategy and Defense Acquisition Reform efforts.
Operational doctrine for CODOG-equipped units balances sortie endurance, sprint profiles, and engineering watch procedures codified in fleet manuals from Royal Navy, US Fleet Forces Command, and Fleetwood-era guides. Transition protocols between diesel and turbine modes are practiced in exercises like RIMPAC, NATO Exercise Trident Juncture, and Exercise Malabar, with sea trials observed by classification societies including ABS. Training at establishments such as HMS Collingwood, Surface Warfare Officers School Command, and HMAS Cerberus emphasizes gearbox failure modes, turbine spool-up times, and fuel management consistent with standards from MIL-STD-1379 and industrial guidelines from SAE International.
The CODOG concept evolved from early 20th-century experimentation with multi-prime-mover ships, accelerated by interwar and Cold War demands for multi-mission frigates and destroyer escorts deployed in conflicts like the Falklands War and the Cold War. Key developmental milestones involved collaborations among Admiralty Engineering Laboratory, U.S. Navy Bureau of Ships, NAVSEA, and industrial consortia including Rolls-Royce, General Electric, MAN SE, and Brown Shipbuilding. Notable retrofit programs and design iterations occurred in projects such as the Type 21 frigate conversions, the Anzac-class frigate procurement, and upgrade cycles across NATO fleets influenced by the Second Cod Wars era and post-Cold War restructuring.
Category:Marine propulsion systems