The Dreadnought Project:Abbreviations

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This page serves as a source for all abbreviations used on The Dreadnought Project.

If you find omissions, please contact us.


AA, A/A or A.A. is an abbreviation for anti-aircraft, normally notating a weapon adapted or designed for use against aeroplanes. In contemporary British sources, guns suited to A.A. fire are more often described as "high angle", or "H.A."


Assistant Chief of Naval Staff (Royal Navy)


A/S can often be held to stand for Anti-Submarine.


Anti-Submarine Division (Royal Navy)


Assistant Director of Operations (Royal Navy)


Sometimes used by the editors for "Annual Report of the Torpedo School"


Above Water, used in describing a torpedo tube that is not a submerged one.

B.L. or BL

Breech Loading. A gun with a breech, but further, in British contemporary use, one that has its propellant loaded separately from its projectile. See Q.F. for a type of gun with a breech that is never referred to by B.L.


The Committee of Imperial Defence was an ad hoc governmental organisation which attempted to define and coordinate British Imperial strategy from after the Second Boer War to the end of the Second World War.

C.O.S. or COS

A Change-over Switch (sometimes called a "group switch") was a large, often cylindrical switch with several rotary positions that would multiplex a number of connections to effect a simultaneous re-routing of related signals. A typical application is to have one in the transmitting station that chooses which of two gunnery directors has its firing, elevation, slew and training circuits passed through to the guns. Having a single switch control all these routings eliminates a source of error and speeds the consistent "changeover".

C.O.S. was also used in primary sources to refer to the Chief of the Admiralty War Staff from 1912 to 1917.


crh stands for Caliber Radius Head. The pointed head of a projectile is described in terms of its ballistic length and the radius of the curvature of its nose. Larger numbers mean a more streamlined profile. Properly, crh is shown as a dual number such as 3/4crh, with the first number indicating the ballistic length and the second number indicating the radius of the curvature, but it is often abbreviated to a single number such as 4crh.


Conning Tower


As used in UK sources, this is a (Long) Hundredweight, or 112 pounds. This is 1/20th of a long ton (2240 pounds) and is sometimes used to indicate the weight of a gun or shipboard fitting.


The Director of the Air Department was in charge of the Air Department at the Admiralty from 1912 to 1915. Replaced by the Director of Air Services.


D.C.N.S. was Deputy Chief of Naval Staff, a Lord Commissioner of the Board of Admiralty responsible in part for the Naval Staff.


"Destroyer Flotilla", used in some contemporary British sources.


Duplex Gyro Oil Unit.


The Director of the Intelligence Division was head of the Royal Navy's Intelligence Division of the Admiralty War Staff, and from 1917, Naval Staff. Title used from 1912 to 1918.


Director of Naval Intelligence (Royal Navy), became the D.I.D. in 1912. Became D.N.I. again circa 1918.


Electro-pneumatic. Used sometimes in describing a type of Fore Bridge Firing Gear.


Follow-the-Pointer. This Wiki uses "F.T.P."


Follow-the-Pointer A type of data receiver in which a signaled indication moves one pointer about a dial and the user is intended to work a handle to make a second pointer match the indication. Often used in sight-setting equipment, but elevation and training receivers are other examples.


Gunnery Control Tower. An armoured cylinder often found on a capital ship, sometimes adjoining or nested within and atop the conning tower.

H.A. or HA

high angle, a term used in contemporary British sources to describe guns and sighting systems able to fire at aircraft.

H.M. or HM

His Majesty, Her Majesty, or the possessive form of either, used in some contemporary British sources, e.g., "Gunnery Manual for HM Fleet".


Naval Intelligence Department. Essentially acted as a Naval Staff from 1887 to 1909. Replaced in 1912 by the Intelligence Division of the Admiralty War Staff.


o/a, o.a. or oa is an abbreviation for overall, and is used when describing the length of a ship. This term refers to the maximum length of a vessel from the two points on the hull most distant from each other, measured perpendicular to the waterline.


Post Centrale, The French term for Transmitting Station.


p/p, p.p., pp or lbp is an abbreviation for length between perpendiculars, and is used when describing the length of a ship. This term refers to the length of a vessel along the waterline from the forward surface of the stem, or main bow perpendicular member, to the after surface of the sternpost, or main stern perpendicular member. This was believed to give a reasonable idea of the ship's carrying capacity, as it excluded the small, often unusable volume contained in her overhanging ends. On some types of vessels this is, for all practical purposes, a waterline measurement. In a ship with raked stems, naturally this length changes as the draught of the ship changes, therefore it is measured from a defined loaded condition.

Q.F. or QF

Quick Firing. A gun whose ammunition carries projectile and powder in one handy, pre-assembled package, like a bullet. See also B.L.


Rarely used in British sources as a "quarter", or 1/4 of a long hundredweight or 28 pounds. It is editorial policy on this Wiki to generally convert all such measures to pounds, e.g., a source indicating "2 cwt, 2 qt." would be related here as "280 pounds".




Royal Gun Factory, situated in Woolwich. This was one of the Royal Navy's primary sources of guns (and torpedoes, before these operations were relocated to Greenock as the R.N.T.F.


Royal Laboratory, situated in Woolwich. It was an early place of torpedo manufacture for the Royal Navy.


Royal Navy Torpedo Factory, situated in Greenock. This was one of the Royal Navy's primary sources of torpedoes.


Remote Power Control. An American technology developed after World War I to allow analog computing machines to directly articulate massive gun mountings in train and elevation.


Torpedo Control Position. Not a contemporary abbreviation, but a convenient one.


Torpedo Control Tower. An armoured cylinder or oval structure often found on a British capital ship, situated just forward of the aft-most turrets.


Transmitting Station. In British parlance, this is the room below decks where fire control calculation occurs and the nexus of data transmission to directors and guns. Not often found in ships smaller than a large cruiser, but later in the war, some small form would exist even in large destroyers. In French, this is Post Centrale (P.C.) and in the US, "Plotting Room" or "Plot".


w/l, w.l. or wl is an abbreviation for waterline, and is used when describing the length of a ship. This term refers to the length of a vessel along the waterline. In a ship with raked stems, naturally this length changes as the draft of the ship changes, therefore it is measured from a defined loaded condition.