Page 130 - NAVAL SCIENCE 3 TEXTBOOK

SIIIP CO NSTR UCTION AND DAl\IAC,E CO NT ROL 135

The section of the ship around the midpoint area is called amid- age from collision or grounding. The spaces between the inner and
ships. Sightings by lookouts are noted and reported as bei.ng off the outer bottoms may form tauks or bilges, which may be used for
port or starboard bow or beam, and off the port or starboard quar- fuel and water stowage or bal1ast (usually concrete or pig iron). If
ter (area abaft of the beam toward thc stern). they are empty, they arc called J10ids (air spaces).
You never go downstairs in a ship; you always go bela IV. To Many of these tanks are fitted with pumps that can transfer liq-
go up to the main deck or above is to go topside. However, if you uids from one tank compartment to another to help keep the ship
climb the mast, stacks, rigging, or any other areas above the solid level or "all an even kee\." The tanks at the extreme bow and stern,
structure of the ship, you go aloft. called the forward (or forepeak) and after peak tnllks, are used for
tril1l//ling the ship (leveling it fore-and-aft).
The top of the main hull is called the //lain deck. The intersec-
S hip Structure
tion of the main deck with the shell or side plating is called the
The hull is the main body of the ship. It is like a box. Its inner con- gllnwale (pronounced gUIl'el). Projections at the joint between the
struction might be compared to the girders of a sted bridge. The side plating and the bottom plating are called bilge keels; their pur-
keel is the backbone of the hull; it is on the centerline like an I-beam pose is to reduce rol1ing of the ship. (A ship rolls from side to side;
running the full length of the bottom of the ship, with heavy cast- it pitches when it goes up and down fore and aft; it yaws when the
ings fore and aft called the stem and stem posts. Girders attached to bow swings to port and starboard because of wave action.)
the keel, cill1cd trmlSl'erse frallles, run athwartships and support the ivlost warships built today have unarmored hulls. Ships of the
wi.ltertight skin or shell platillg, which forms the sides and bottoms last cenhlry with armored hulls (the old battleships and heavy
of the ship. Most Nav)' ships also have /Ollgitlldilltll frames fun- cruisers) had vertical armored belts of very thick steel running
ning fore and aft. \,"hen covered by plating, the longitudinal and fore and aft along the sides of the hull to protect engine rooms and
athwartship frames form a honcycomb structure in the bottolll of magazi.nes from torpedoes, shell nre, and missiles. They also had
the ship called a double llOtt011l. This type of construction greatly horizontal armor-steel plates built into exposed decks to protect
strengthens the bottom and 111i.lkes the ship Illore resistant to dal11- against plunging bombs, shells, and missiles. The I\'aterlinc is the

fRAME

f~:~~::::IT::::~:;:::~~~:~;;;;;~' LONGITUDINAL BULKHEAD
LIGHTEN ING HOlE
1: TRANSVERSE
~~;~~:~~~~f~~~~~~5~;i;~-- DECK LONGITUDINAL
BULKHEAD

CENTER VERTICAL KEEL
BILGE KEEL

Transverse and longitudinal structure of a ship. Note that transverse beams and bulkheads run athwartships, while longitudinals run the "long
way," from stem to stern.