Combined diesel or gas (CODOG) is a type of

propulsion Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived f ...

system for

ship A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research, and fishing. Ships are generally distinguished ...

s that need a maximum speed that is considerably faster than their cruise speed, particularly

warship A warship or combatant ship is a naval ship that is built and primarily intended for naval warfare. Usually they belong to the armed forces of a state. As well as being armed, warships are designed to withstand damage and are usually faster ...

s like modern

frigate A frigate () is a type of warship. In different eras, the roles and capabilities of ships classified as frigates have varied somewhat. The name frigate in the 17th to early 18th centuries was given to any full-rigged ship built for speed an ...

s or

corvette A corvette is a small warship. It is traditionally the smallest class of vessel considered to be a proper (or " rated") warship. The warship class above the corvette is that of the frigate, while the class below was historically that of the slo ...

s. For every propeller shaft there is one

diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-cal ...

for cruising speed and one

geared A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth (called ''cogs''), which mesh with another (compatible) toothed part to transmit (convert) torque and speed. The basic pr ...

gas turbine A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directio ...

for high speed dashes. Both are connected to the shaft with

clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...

es; only one system is driving the ship, in contrast to 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 A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but ...

at high speed is poor compared to CODAG.

CODOG vessels

* MGB 2009, a modified

Motor Gun Boat The motor gun boat (MGB) was a small, high-speed British military vessel of the Second World War, which was armed with a mix of guns, in contrast to the physically similar motor torpedo boat (MTB), whose main offensive weapon were torpedoes. ...

of the

Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against Fr ...

(1947), and *The two German torpedo boats ''Pfeil'' and ''Strahl'' (''Vosper'' class, 1963-65) *The

US Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

s (built 1966-1971) *The US Coast Guard s (from 1967) *s of the

Royal Canadian Navy The Royal Canadian Navy (RCN; french: Marine royale canadienne, ''MRC'') is the naval force of Canada. The RCN is one of three environmental commands within the Canadian Armed Forces. As of 2021, the RCN operates 12 frigates, four attack subma ...

*s, and *s of the

German Navy The German Navy (, ) is the navy of Germany and part of the unified ''Bundeswehr'' (Federal Defense), the German Armed Forces. The German Navy was originally known as the ''Bundesmarine'' (Federal Navy) from 1956 to 1995, when ''Deutsche Mari ...

*s of the Philippine Navy *s of the

Royal Australian Navy The Royal Australian Navy (RAN) is the principal naval force of the Australian Defence Force (ADF). The professional head of the RAN is Chief of Navy (CN) Vice Admiral Mark Hammond AM, RAN. CN is also jointly responsible to the Minister o ...

(RAN) and

Royal New Zealand Navy The Royal New Zealand Navy (RNZN; mi, Te Taua Moana o Aotearoa, , Sea Warriors of New Zealand) is the maritime arm of the New Zealand Defence Force. The fleet currently consists of nine ships. The Navy had its origins in the Naval Defence Act ...

(RNZN) *other MEKO type frigates or corvettes *s of the

Royal Danish Navy The Royal Danish Navy ( da, Søværnet) is the sea-based branch of the Danish Defence force. The RDN is mainly responsible for maritime defence and maintaining the sovereignty of Danish territorial waters (incl. Faroe Islands and Greenland). O ...

*s of the South Korean Navy *s of the

Swedish Navy The Swedish Navy ( sv, Svenska marinen) is the naval branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet () – as well as marine units, the Amphibious Corps (). In Swedish, vessels ...

*s of the

Indian Navy The Indian Navy is the maritime branch of the Indian Armed Forces. The President of India is the Supreme Commander of the Indian Navy. The Chief of Naval Staff, a four-star admiral, commands the navy. As a blue-water navy, it operates si ...

*s of the Brazilian Navy * of the Bangladesh Navy *{{sclass2, Gepard, frigate, 1s of the Russian and Vietnamese Navies *''

118 WallyPower 118 WallyPower, christened ''Galeocerdo'', is a luxury motor yacht with a maximum speed of , produced by Wally Yachts. The yacht is narrow and angular in design with black glass housing, driven by three Vericor TF50 gas turbines generating , eac ...

'', luxury yacht Marine propulsion