page_title: Oberon-class submarine
section_title: Propulsion systems
hierarchical_section_title: Oberon-class submarine / Design and construction / Propulsion systems
caption_attribution_description: Im Inneren von HMS Otus: Maschinenraum
context_page_description: The Oberon class was a ship class of 27 British-designed submarines operated by five different nations. They were designed as a direct follow-on from the Porpoise class: physical dimensions were the same, but stronger materials were used in hull construction, and updated equipment was fitted.
  The submarines were built between 1957 and 1978 by four shipyards: Cammell Laird, Chatham Dockyard, Scotts Shipbuilding and Engineering Company and Vickers-Armstrongs. Thirteen of the submarines were operated by the Royal Navy, six by the Royal Australian Navy, three by the Brazilian Navy, three by the Royal Canadian Navy/Canadian Forces Maritime Command, and two by the Chilean Navy.
  The Oberons operated during the height of the Cold War, with duties including surveillance, tracking of other ships and submarines, delivery and retrieval of special forces personnel, and serving as targets for anti-submarine training. Submarines of the class were in service until 2000. As of 2015, eight of the submarines are preserved intact as museum vessels, another three are partially preserved, and one is in private ownership and awaiting conversion for display.
context_section_description: The class used diesel-electric propulsion, with lead-acid batteries to provide power when the engines cannot be used. Each vessel has two Admiralty-pattern V-16 diesel engines (ASR1 16VMS), each driving one 1280-kW 880-V generator. These can provide power directly to the two 3,000-brake-horsepower (2,200 kW) electric motors, one directly connected to each propeller, or for charging batteries. The diesel engines can only be operated with external ventilation, but this can be obtained either while on the surface or when shallowly submerged by use of two snorkels which can be raised from the fin. One snorkel brings in new air to the boat, while the other takes exhaust fumes from the engines. The ventilation system is designed so the fresh air spreads through the boat.
  The generators are cooled by an internal fan on the shaft which circulates air through a filter and water-cooled heat exchanger within the casing. A grill allows pressure equalisation inside and out. The generator has one pedestal bearing fed with oil from the diesel engine lubrication supply and is fitted with an internal heater to prevent condensation when not running.
  The submarine has two batteries, each comprising 224 2V cells (type D7420) giving  a nominal 440 V output. One battery is located underneath the crew accommodation compartment, and the other under the control compartment. Each battery has a switch circuit in the middle so it can be split into two banks of 112 cells.  The cells are designed to deliver 7420 Ah over a period of five hours. All steelwork within the battery compartments is lined with rubber to protect the metal from attack by acid, and also all conducting material is insulated to prevent risks of electric shock. Waxed timber is used to make framing and crawlways to access the batteries and support them because of its resistance to acid. The battery compartment has a sump to collect any spilled liquids.  Each cell weighs 1,120 lb (510 kg), measures about 4 by 0.16 by 0.12 feet (1.219 m × 0.049 m × 0.037 m), and contains 18.5 gallons of electrolyte. Cells are held tightly in place with wooden wedges to prevent movement with the boat. Each cell has four connector bolts to each electrode and an agitator pipe which bubbles air through the cell to ensure the electrolyte remains mixed and uniform. Cooling water is fed through pipes attached to the electrode connectors to  prevent overheating and the battery temperature is monitored.
  In operation, each battery is charged until the voltage reaches 560 V, then allowed a further hour's charging. Fortnightly, it should be allowed 5 hours' charging after reaching 560 V to ensure a maximum charge is reached. Every two months, the battery should be given an equalising charge of eight hours to ensure all cells have reached their maximum.  The battery is designed to operate with a specific gravity of the electrolyte between 1.080 and 1.280. Initial charging current should be around 1650 amps for s.g. below 1.180, 1250 A above 1.180, falling to 280 A when charging is complete. At a voltage around 538 V, the cells begin to give off explosive hydrogen gas, so the applied power is reduced during charging to keep voltage below this value until current falls to 280 A, which is then maintained while voltage is allowed to rise until  the requisite voltage and charge time are reached. In an emergency, the charging current can be raised to 2000 A. To maintain overall capacity, batteries need to be completely discharged over a five-hour period once every four months and then completely recharged. The battery compartments are sealed to prevent gases escaping into the submarine, or salt water entering, which inside a battery would cause the release of poisonous chlorine gas.  Ventilation fans are used to extract hydrogen released by the cells and catalytic converters are placed strategically through the submarine to remove hydrogen from the air by recombining it with oxygen to form water.
  Each of the two propellers on the submarine is connected to a 3000 bhp DC electric motor. Each motor is designed with two se
caption: Engine compartment on HMS Otus, twin V16 diesel engines
exif: {}