Engine order telegraph

An engine order telegraph or E.O.T., also referred to as a chadburn,[1] is a communications device used on a ship (or submarine) for the pilot on the bridge to order engineers in the engine room to power the vessel at a certain desired speed.

Queen Mary bridge
Several engine order telegraphs on the bridge of RMS Queen Mary


In early vessels, from the 19th century until about 1950, the device usually consisted of a round dial about nine inches (~20 centimetres) in diameter with a knob at the center attached to one or more handles, and an indicator pointer on the face of the dial. There would also be a revolutions per minute indicator, worked by a hand crank. Modern E.O.T.s on vessels which still use them use electronic light and sound signals.


Traditional E.O.T.s required a pilot wanting to change speed to "ring" the telegraph on the bridge, moving the handle to a different position on the dial. This would ring a bell in the engine room and move their pointer to the position on the dial selected by the bridge. The engineers hear the bell and move their handle to the same position to signal their acknowledgment of the order, and adjust the engine speed accordingly. Such an order is called a "bell," for example the order for a ship's maximum speed, flank speed, is called a "flank bell."[2]

For urgent orders requiring rapid acceleration, the handle is moved three times so that the engine room bell is rung three times. This is called a "cavitate bell" because the rapid acceleration of the ship's propeller will cause the water around it to cavitate, causing a lot of noise and wear on the propellers. Such noise is undesirable during conflicts because it can give away a vessel's position.

Compared to remote control throttle

Modern engine room telegraph/remote control handle in Engine Control Room (ECR) on board a merchant ship. ECR Lever is not currently active as the system pictured is in direct bridge control mode.

On most modern vessels with direct combustion engines or electric propulsors, the main control handle on the bridge acts as a direct throttle with no intervening engine room personnel. As such, it is regarded under the rules of marine classification societies as a remote control device rather than an EOT, though it is still often referred to by the traditional name. This is somewhat confusing, as the classification society rules for merchant ships still in fact require an EOT to be provided, to allow orders to be transmitted to the local control position in the engine room in the event that the remote control system should fail. The EOT is required to be electrically isolated from the remote control system. However, it may be mechanically linked to the main control handle, allowing telegraph orders to be given using the same user interface as for remote control orders. Traditional EOTs (though in a more modern form) can still be found on all nuclear powered ships and submarines as they still require an engineering crew member to operate the throttles for the steam turbines that drive the propellers. EOTs can also be found on older vessels that lack remote control technology, particularly those with conventional steam engines.

Remote control systems on modern ships usually have a control transfer system allowing control to be transferred between locations. Remote control is usually possible from two locations the bridge and the Engine Control Room (ECR). Some ships lack a remote control handle in the ECR. When in bridge control mode, the bridge handle directly controls the engine set point. When in Engine Control Room mode the bridge handle sends a telegraph signal to the ECR and the ECR handle controls the set point of the control system. In local control, the remote control system is inactive and the bridge handle sends a telegraph signal to the local control position and the engine is operated by its manual controls in the engine room

Order transmission

Block diagram of the EOT signal system

Two telegraph units and alarms must be installed, one on the bridge and one in the engine room. The order is given by moving the bridge unit's handle to the desired position on the dial face. This sends an electrical signal to the EOT placed in the engine room whose pointer acquires a position according to the signal given from the bridge. An audible alarm sounds at both ends. Accordingly, the watch-keeping engineer acknowledges the order by moving the handle of the engine room EOT to the required position and takes necessary action. This sends an electrical signal to the bridge EOT unit, causing its pointer to acquire the respective position. The alarm stops ringing to acknowledge that the order has been carried out.

Typical dial positions

USS LST-325's bridge engine order telegraph

Many past ships have the following dial indications:

  • Flank ahead ( 1940-)
  • Full Ahead
  • Half Ahead
  • Slow Ahead
  • Dead Slow Ahead
  • Standby
  • Stop
  • Finished With Engines
  • Dead Slow Astern
  • Slow Astern
  • Half Astern
  • Full Astern
  • Emergency Astern ( 1940-)

Any orders could also be accompanied by an RPM order, giving the precise engine speed desired. Many modern ships have the following dial indications:

  • Full Ahead Navigation (on notice to increase or reduce)
  • Full Ahead
  • Half Ahead
  • Slow Ahead
  • Dead Slow Ahead
  • Stop
  • Dead Slow Astern
  • Slow Astern
  • Half Astern
  • Full Astern

Finished with Engines and Standby conveyed via separate control panel.

See also


  1. ^ "The Chadburn Ships' Telegraph Society". Retrieved 2 July 2011.
  2. ^ Halpern, Samuel (18 September 2007). "Speed and Revolutions". Encyclopedia Titanica. Retrieved 6 January 2013.

External links

Bridge (nautical)

The bridge of a ship is the room or platform from which the ship can be commanded. When a ship is under way, the bridge is manned by an officer of the watch aided usually by an able seaman acting as lookout. During critical maneuvers the captain will be on the bridge, often supported by an officer of the watch, an able seaman on the wheel and sometimes a pilot, if required.

Bungsberg (ship)

Bungsberg (originally named Eva, factory body number 646) was a cargo ship built in 1924 at Howaldtswerke in Hamburg, Germany, for China Reederei AG. She had three sister ships:

Troja - hull no 643 (Deutsche Levante-Linie, Hamburg, 1922)

Kreta - hull no 644 (Bremer Dampfschiffahrtsgesellschaft, Bremen, 1923)

Syra - hull no 645 (Deutsche Levante Linie, Hamburg)Bungsberg was sunk in Tallinn Bay in Estonia on 24 March 1943 by a mine laid by a Soviet airplane. Bungsberg′s last owner was Aug. Bolten Wm Miller's Nachfolger (GmbH & Co.) KG.

Today, Bungsberg′s wreck is a popular dive site for recreational divers. She lies on her keel in an upright position at a depth of 38 meters (125 feet). Her funnel and after mast are missing, as are the upper structures of her bridge. Damage from the mine explosion is clearly visible on her starboard bow. All four of her cargo holds are empty.

Some papers retrieved from Bungsberg′s wreck and her engine order telegraph are kept at the Estonian Maritime Museum in Tallinn, Estonia.

Dornier Do X

The Dornier Do X was the largest, heaviest, and most powerful flying boat in the world when it was produced by the Dornier company of Germany in 1929. First conceived by Dr. Claude Dornier in 1924, planning started in late 1925 and after over 240,000 work-hours it was completed in June 1929.During the years between the two World Wars, only the Soviet Tupolev ANT-20 Maksim Gorki landplane of a few years later was physically larger, but at 53 metric tons maximum takeoff weight it was not as heavy as the Do X's 56 tonnes.

The Do X was financed by the German Transport Ministry and in order to circumvent conditions of the Treaty of Versailles, which forbade any aircraft exceeding set speed and range limits to be built by Germany after World War I, a specially designed plant was built at Altenrhein, on the Swiss portion of Lake Constance.

The type was popular with the public, but a lack of commercial interest and a number of non-fatal accidents prevented more than three examples from being built.


EOT may stand for:

Electrical Overhead Travelling, a type of overhead gantry crane

Embedded OpenType, a font file format

End-of-tape, a term in magnetic tape data storage

End-of-train device, as used by the railroad industry

End-of-Transmission character, a transmission control character in telecommunication

Engine order telegraph, a ship or submarine's speed control

Enterprise of Things, a term for Internet of Things devices used in a business environment

Eot (island), in Micronesia

Equation of time, a timekeeping correction

Equivalent oxide thickness, insulating property of a dielectric coating in a transistor

Ethnikos Organismos Tourismou (Greek National Tourism Organization), Greek tourism promotion agency

Extension of Time, an extension to the period of time allowed in a construction contract

Extraordinary optical transmission, an optical phenomenon

Massachusetts Executive Office of Transportation (EOT), a division of the Massachusetts state government

Fire Fighter (fireboat)

Fire Fighter is a fireboat which served the New York City Fire Department from 1938 through 2010, serving with Marine Companies 1, 8 & 9 during her career. The most powerful diesel-electric fireboat in terms of pumping capacity when built in 1938, the Fire Fighter fought more than 50 major fires during her career, including fires aboard the SS Normandie in 1942, the 1973 collision of the Esso Brussels and SS Sea Witch, and the terrorist attacks on September 11, 2001.

Flank speed

Flank speed is a nautical term referring to a ship's true maximum speed, but it is not equivalent to the term full speed ahead. Usually, flank speed is reserved for situations in which a ship finds itself in imminent danger, such as coming under attack by aircraft. Flank speed is very fuel-inefficient and often unsustainable because of propulsion system limitations. The related term emergency may not be any faster than flank, but it indicates that the ship should be brought up to maximum speed in the shortest possible time.Other speeds include one-third, two-thirds, standard, and full. One-third and two-thirds are the respective fractions of standard speed. Full is greater than standard, but not as great as flank.

In surface ship nuclear marine propulsion, the differentiation between full speed and flank speed is of lesser significance, because vessels can be run at or very near their true maximum speed for a sustained duration with little regard for fuel expended, a top consideration of oil-powered ships.

In US nuclear submarine propulsion, full speed is 50% reactor power. Flank speed is 100% power, although limits may be reached for the propulsion turbine first stage pressure or for reactor thermal power (in MW) (depending upon the specifics of the individual propulsion plant) before 100% reactor power is reached. In addition, for flank speed, the reactor's main coolant pumps must also be shifted into fast speed.

"Flank speed" is exclusively an American phrase and as such is unknown in Commonwealth ("White Ensign") navies. The Commonwealth navies use the following telegraph commands:

Slow Ahead/Astern, the number of revolutions is standardized for the individual ship, and as such is unstated;

Half Ahead/Astern, accompanied by an order for a specific power setting (e.g., "half ahead both engines, revolutions 1500");

Full Speed Ahead/Astern. This is reserved for emergencies, and as such the word "speed" is included to distinguish it from the other commands previously mentioned. No specific power setting is expressed, it being implicit that maximum power is required.

La Sultana

La Sultana is a yacht that has been refitted from a Soviet era ferry. She was launched in 1962, under the name Aji-Petri and was the fifth in a series of 12 ships that were originally built for the Russian fleet. Her purpose was to transport freight and passengers between the ports of Odessa, Yalta, Sebastopol and Istanbul between the Azov and Black seas. During the Cold War, the ship was believed to be used as a Soviet spy vessel. During the refitting process several spying instruments were discovered, including a radioactivity detector and thick aluminum insulation across the entire boat.

Lee helm

Lee helm is the tendency of a sailboat to turn away from the wind while under sail. It is the opposite of weather helm which is the tendency of a sailboat to "round up" into the wind. A boat with lee helm will be difficult to sail Close Hauled and tacking may be difficult.

Melrose (ferry)

Melrose was the first San Francisco Bay ferry designed to carry automobiles. Southern Pacific Transportation Company and predecessor railroads had been operating ferries between San Francisco and Oakland, California since 1862. Some ferries were equipped to carry team-drawn wagons, but the increasing number of automobiles requiring transport encouraged building of a ferry with an unobstructed lower deck for automobiles and 400 seats on an upper deck for passengers. Melrose was launched without engines on 11 April 1906. Installation of engines being built at San Francisco's Union Iron Works was delayed by the 1906 San Francisco earthquake a week after launching. The ferry was not completed until 1909. The side wheels were powered by two inclined tandem engines to avoid main deck obstruction by a traditional walking beam engine.The successful design of Melrose encouraged completion of sister ship Thoroughfare in 1912. Thoroughfare cost $170,000 with capacity for 97 automobiles and 45 team-drawn wagons. These two ferries offered departures at 30-minute intervals through the daylight and evening hours. Automobiles were carried on the "creek route" until new loading facilities were completed on the Oakland pier in 1921. Thoroughfare steamed into the ferry slip at full speed when her engine-order telegraph malfunctioned on 14 August 1913. The ferry was less damaged than the slipway and resumed service shortly after the engine-order telegraph was repaired.Melrose collided with the Southern Pacific ferry Bay City in a patch of dense fog on 26 January 1913. Both ferries continued in service after repairs. Two Melrose deckhands were killed while attempting to rescue a man overboard on 9 July 1917 when the lifeboat they had launched to recover the passenger was drawn into the maneuvering ferry's paddle wheel. Melrose narrowly avoided collision with the freighter K.J.Luckenback in fog on 4 February 1922. Melrose ran aground while maneuvering to avoid collision, and required the assistance of tugs to be refloated. In July 1926, Melrose suffered a mid-bay mechanical breakdown requiring assistance of tugs. The rescue tug accidentally rammed Melrose while passing a tow line. Melrose started flooding and was grounded on a mud bar to prevent sinking until repairs could be made.Melrose was retired in 1931 and Thoroughfare was sold in 1935 to become a fish reduction plant in Benicia, California. Completion of the San Francisco–Oakland Bay Bridge in 1936 ended the need for automobile ferries between Oakland and San Francisco.

RMS Alcantara (1913)

SS Alcantara was an ocean liner that went into service just weeks before the start of World War I, was converted to an armed merchant cruiser in 1915, and was sunk in combat with the German armed merchant cruiser SMS Greif in 1916.

Ship's wheel

A ship's wheel or boat's wheel is a device used aboard a water vessel to steer that vessel and control its course. Together with the rest of the steering mechanism, it forms part of the helm. It is connected to a mechanical, electric servo, or hydraulic system which alters the vertical angle of the vessel's rudder relative to its hull. In some modern ships the wheel is replaced with a simple toggle that remotely controls an electro-mechanical or electro-hydraulic drive for the rudder, with a rudder position indicator presenting feedback to the helmsman.

Steering engine

A steering engine is a power steering device for ships.

TSS Earnslaw

The TSS Earnslaw is a 1912 Edwardian vintage twin screw steamer plying the waters of Lake Wakatipu in New Zealand. It is one of the oldest tourist attractions in Central Otago, and the only remaining commercial passenger-carrying coal-fired steamship in the southern hemisphere.


Telegraphy is the long-distance transmission of textual messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas pigeon post is not. Ancient signalling systems, although sometimes quite extensive and sophisticated as in China, were generally not capable of transmitting arbitrary text messages. Possible messages were fixed and predetermined and such systems are thus not true telegraphs.

The earliest true telegraph put into widespread use was the optical telegraph of Claude Chappe, invented in the late eighteenth century. The system was extensively used in France, and European countries controlled by France, during the Napoleonic era. The electric telegraph started to replace the optical telegraph in the mid-nineteenth century. It was first taken up in Britain in the form of the Cooke and Wheatstone telegraph, initally used mostly as an aid to railway signalling. This was quickly followed by a different system developed in the United States by Samuel Morse. The electric telegraph was slower to develop in France due to the established optical telegraph system, but an electrical telegraph was put into use with a code compatible with the Chappe optical telegraph. The Morse system was adopted as the international standard in 1865, using a modified Morse code developed in Germany.

The heliograph is a telegraph system using reflected sunlight for signalling. It was mainly used in areas where the electrical telegraph had not been established and generally uses the same code. The most extensive heliograph network established was in Arizona and New Mexico during the Apache Wars. The heliograph was standard military equipment as late as World War II. Wireless telegraphy developed in the early twentieth century. Wireless telegraphy became important for maritime use, and was a competitor to electrical telegraphy using submarine telegraph cables in international communications.

Telegrams became a popular means of sending messages once telegraph prices had fallen sufficiently. Traffic was became high enough to spur the development of automated systems – teleprinters and punched tape transmission. These systems led to new telegraph codes, starting with the Baudot code. However, telegrams were never able to compete with the letter post on price, and competition from the telephone, which removed their speed advantage, drove the telegraph into decline from 1920 onwards. The few remaining telegraph applications were largely taken over by alternatives on the internet towards the end of the twenty-first century.


USS LST-325 is a decommissioned tank landing ship of the United States Navy, now docked in Evansville, Indiana, USA. Like many of her class, she was not named and is properly referred to by her hull designation (LSTs in service after July 1955 were named after U.S. counties and parishes).

The ship was listed on the U.S. National Register of Historic Places in 2009. The property was added to the National Register of Historic Places (NRHP) on 24 June 2009 and the listing was announced as the featured listing in the National Park Service's weekly list of 2 July 2009.

USS Recruit (TDE-1)

USS Recruit (TDE-1, later TFFG-1) was a landlocked "dummy" training ship of the United States Navy, located at the Naval Training Center in the Point Loma area of San Diego. She was built to scale, two-thirds the size of a Dealey-class destroyer escort, and was commissioned on July 27, 1949. Recruit was commissioned for 18 years, for much of that period the only landlocked ship to hold that status in the U.S. Navy.

"Sailing" on a sea of concrete at the Naval Training Center, she assisted with the training of over 50,000 new recruits per year, providing an education in the fundamentals of shipboard drills and procedures, using standard deck and bridge gear like that found on all naval vessels, including lifelines, accommodation ladders, signal halyards, searchlights, the engine order telegraph and the helm. However, due to her landlocked status, Recruit lacked an engine or screw, and therefore was affectionately nicknamed the "USS Neversail." (The same nickname, "The Neversail," was also applied to the landlocked "ship" USS Commodore at NTC Bainbridge in Maryland.) Reflecting her dual identity as both a ship and a building, she was also known as Building 430, located on Geary Drive between Evans and Chauncey roads.

Recruit was decommissioned in March 1967, due to the inability to classify the unique ship in a computerized registry of Navy vessels. However she was later recommissioned in 1982, and refurbished to look like an Oliver Hazard Perry class frigate. Commissioned or otherwise, she served continuously as a training facility from her construction in 1949 until the base was closed by the BRAC commission in 1997.

The Recruit still stands, currently unused, with the hope that she will someday become a maritime museum. She is included in the Naval Training Center's listing on the National Register of Historic Places. She now stands adjacent to a retail area of Liberty Station, as the redeveloped base is known, and can be seen from North Harbor Drive. She appears to be the only surviving example of the Navy's landlocked ships, or "landships". Her predecessor USS Recruit, a wooden "battleship" built in Union Square in New York City in 1917, was dismantled in 1920. The USS Commodore, located at the United States Naval Training Center, Bainbridge in Maryland, was dismantled when the base closed in the 1970s. The USS Bluejacket, located at Naval Training Center Orlando in Florida, was also dismantled when this base closed March 31, 1995.

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