Abaft

‘Aft of’.

Abeam

Off to the side of (on the axis of the ship’s beam).

Athwartships

Running across the ship, at right angles to a line from the bow to the stern.

Aft

The part of the ship that is towards the stern (behind) from the point of reference ("aft of the deckhouse"), or the rear portion of the ship.

Beam

The maximum width of the ship.

Binnacle

The stand and housing that contains the ship’s magnetic compass.

Bow

[Rhymes with "wow"] The most forward part of the ship that meets the water.

Bridge

The area from which the ship is steered and controlled, usually on top of the deckhouse and consisting of an enclosed central pilot house with outside "wings" extending to each side of the ship, affording a view forward and aft. The "flying bridge" is a second, unenclosed control station, usually above the enclosed bridge, used in good weather or when better visibility is needed.

Bulkhead

An internal vertical wall in a ship, often running athwartships. Bulkheads may be, but are not necessarily, watertight.

Bunker

Storage compartment for fuel. When ships ran on coal this referred to the coal bunkers. Today, it also refers to fuel oil tanks. The O’Brien’s maximum bunker capacity is more than 1800 tons, enough to steam about 19,000 nautical miles at 11 knots.

Bunker C

Heavy fuel oil used in many ships; sometimes called "black oil."

Bunkering

Refueling. See Bunker.

Charley Noble

The smoke stack for the galley range (coal burning, on the O’Brien).

Crow’s Nest

A lookout’s station at a high location on the ship, often enclosed to provide some protection from the weather. On the O’Brien, a roofed cylindrical enclosure mounted near the top of the forward mast, and the subject of a constant battle these days to keep it from becoming a pigeon’s nest.

Deadweight Tons

The weight of all cargo and stores (including fuel, water, food and other supplies) carried by a ship. For a cargo ship it is one of the primary measures of ship’s size (along with gross tons), as it approximates the cargo carrying capacity of the ship. Commonly expressed in long tons, 2240 lb. The O’Brien’s deadweight tonnage is 10,735.

Depth

The vertical distance between the deck and the keel. The depth of the O’Brien’s hull is 34 ft 5-1/2 in.

Displacement Tons

The actual total weight of the ship in long tons, equal to the weight of water it displaces when floating. The O’Brien’s maximum displacement tonnage is 14,245.

Draft

The vertical distance from the waterline to the lowest point of the ship; the water in which the ship travels must be deeper than the draft. The O’Brien’s maximum draft is 27 ft 7 in.

Engine Room Telegraph

The signal system used for engine speed and direction orders. A handle on the bridge controls a pointer and bell in the engine room to send the order, and a handle in the engine room controls a pointer and bell on the bridge telegraph to acknowledge the order.

Galley

Ship’s kitchen.

Gross Tons

A measure of the internal volume (not the weight) of the ship, expressed as 100 sq ft to the ton; includes all enclosed spaces, including bridge and living spaces. Formerly a common means of measuring the size of a merchant ship. For modern cargo ships deadweight tonnage is now the most common measure. The O’Brien’s gross tonnage is 7176.5.

Funnel (Stack)

The "smokestack" on top of the deckhouse containing the uptakes from the boilers, with an opening at the top to discharge the exhaust gas (or "stack gas").

Gyrocompass

A heading indicator system used to steer the ship. Operates on the principle that a whirling mass becomes rigid in space. A heavy wheel mounted in a system of pivots (gymbals) is spun at high RPM by an electric motor and resists being displaced from its axis of rotation. As the ship changes heading, pitches, and rolls around it, the gyro wheel remains stationary in its gymbals. The O’Brien’s master gyro (which looks like R2D2 in "Star Wars") is located in the chartroom on the starboard side aft of the bridge. Electrical repeaters are located at the helm and other locations, displaying the ship’s heading. The gyrocompass’ indications are much more stable and free from errors that those of the magnetic compass.

Head

Ship’s toilet.

Helm

The wheel or other control used to steer the ship. On the O’Brien, wheels are located in the pilothouse and on the flying bridge. They connect to a hydraulic telemotor system that controls a steam engine in a compartment at the stern that moves the rudder.

House, or Deckhouse

The central superstructure extending above the hull and main deck; in the O’Brien, it contains the crew’s and officers’ quarters, galley, heads, navigation and radio spaces, the bridge, etc.

Keel

The main central structural member extending along the bottom of the hull.

Knot

One nautical mile per hour, 1.15 MPH; at sea speeds, the O’Brien moves at about 11 knots.

Length OA

(Length overall) The overall length of the ship, from the aft-most part to the forward-most part. The O’Brien’s LOA is 441 ft 6 inches.

Length BP (Length between perpendiculars)

The forward perpendicular is commonly defined as the intersection of the waterline and the bow at the fully loaded draft; the aft perpendicular is the axis of the rudder post. The O’Brien’s length BP is 416 ft.

Length WL

(Length on the waterline) The linear distance from the bow to the stern at the fully loaded waterline.

Mess

Crew’s dining room.

Nautical Mile

Approximately 6080 feet, or 1.15 statute miles.

Port

Facing forward, the left side of the ship. To remember, port and left have the same number of letters.

RDF (or DF)

Radio Direction Finder — a specialized navigation receiver with an antenna that can be rotated to sense the direction from which a radio signal is coming. Located on the starboard side of the flying bridge on the O’Brien, with the controls in the the chartroom immediately below.

SHP

Shaft horsepower - power delivered to the propeller shaft. The O’Brien’s main engine is rated at 2500 SHP.

Scuttlebutt

Ship’s drinking fountain; in slang usage, rumors (discussed around the scuttlebutt).

Starboard

When facing forward, the right side of the ship.

Stern

The back end of the ship.

Uptakes

Ductwork extending upward from the tops of the boilers to carry exhaust gas out the top of the funnel.