Ship Construction

In civilian life you are accustomed to such terms as upstairs, downstairs, windows, floors, ceiling and walls. In the Navy you must learn to describe objects with Navy terminology. To use civilian terminology aboard ship marks you a landlubber -- a scornful term applied to those who know nothing of the sea.

In this lesson you will learn terms used to express directions and locations aboard ship. In addition, you will learn the major structural features and terminology associated with a ship.

Ship Directions

Lengthwise direction on a ship is fore and aft. Crosswise is athwartships.The front of the ship is the bow, and the rearmost is the stern. To move forward toward the bow is to go forward, and to move toward the stern is to go aft.

A ship is divided lengthwise in half by the centerline. When you face forward along the centerline, everything to your right is starboard and everything to your left is port.

You never go downstairs in a ship -- you go below. To go up is to go topside. But if you climb the mast, stacks, rigging or any other area above the highest solid structure, you are going aloft.

Hull

The hull is the supporting body of a ship. It may be likened to an envelope. Inside the hull are strengthening members to prevent the envelope from collapsing. The hull also contains partitions that form machinery, berthing, mess and other spaces.

Keel

The keel is the backbone of the ship. The keel of most steel ships does not extend below the ship's bottom; therefore, it is known as a flat keel. Its usual shape is that of an I-beam. All other members used in constructing the hull are attached either directly or indirectly to the keel.

Ship's Interior

The interior of a ship is divided into compartments by vertical walls, called bulkheads, which run both transversely and longitudinally. Most bulkheads are merely partitions, but spaced at appropriate intervals, they serve as transverse watertight bulkheads. These bulkheads extend from the keel to the main deck and from side to side to provide extra strengthening. Bulkheads partition the hull into independent watertight sections. Large ships have a series of longitudinal side bulkheads and tanks that provide protection against torpedoes.

The outer tanks are usually filled with oil or water; the inner tanks, called voids, are empty. The innermost bulkhead is called the holding bulkhead.

Water Level

The water level along the hull of a ship afloat is the waterline. The vertical distance from the bottom of the keel to the waterline is the ship's draft. Freeboard is the distance from the waterline to the main deck.

Decks

The "floors" of a ship are called decks. They divide the ship into layers and provide additional hull strength and protection for internal spaces. The under surface of each deck forms the overhead (not the ceiling) of the compartment below.

A deck or part of a deck exposed to the weather is called a weather deck. Bulwarks are a solid fence along the gunwale of the main (weather) deck. The bulwarks are fitted with freeing ports (scuppers) to permit water to run off during heavy weather.

A deck that extends from side to side and stem to stem is a complete deck. On an aircraft carrier the uppermost complete deck is the flight deck -- from which aircraft take off and land. On all ships, except aircraft carriers, the uppermost complete deck is the main deck. On an aircraft carrier the hangar deck is the main deck. The hangar deck is the deck on which aircraft are stowed and serviced when not on the flight deck. The first complete deck below the main deck is the second deck, the next the third, the next the forth and so on.

The following definitions relate to decks in modern ships:

• Companionways (ladders). They lead from one deck level to another and may or may not be covered by hatches.
• Flats. Plating or gratings installed only to provide working or walking surfaces above bilges.
• Forecastle (pronounced "fohk'sel") deck. Deck above the main deck at the bow. Ships that do not have raised forecastles are called flush-deckers.
• Gallery Deck. First half or partial deck below the flight deck on an aircraft carrier.
• Levels. This is a general term used to designate deck heights above the main deck. The first level above the main deck is the 01 (pronounced oh-one) level; the second (02) level, and so on.
• Poop deck. A partial deck above the main deck located all the way aft. A flush-decker does not have a poop deck, so the stern area of the main deck is called the main deck aft or the fantail.
• Quarterdeck. The quarterdeck is not an actual deck, but an area designated by the commanding officer for the conduct of official functions, and serves as the station of the officer of the deck. Its location in port depends on how the ship is moored.
• Compartments. They are the "rooms" of a ship. Some compartments are called rooms, such as the wardroom, stateroom, engine room and others. Generally speaking, one does not use the word "room." You never refer to the space where you sleep as the bedroom, nor the place where you eat as the dining room. These spaces are called the berthing compartment and the mess deck.