Page 14 - NAVAL SCIENCE 3 TEXTBOOK

SEA POWER AN D NATIO NA L SECUR ITY 19

Modern Merchant Ships
Timkers, ships designed to GlIT)' liquid cargoes ill bulk quantities,
arc the Illost numerous ships in the active U.S. merchant marine
and arc the most COlllillo n type of ship plying the high seas. They
V'U)' greatly in size, with the largest modern jumbo tankers rang-
ing lip to over a half million tons. Large tankers arc used lll<1iniy
to carry crude oil from oil producing regions to refineries. Smaller
ones Ciln carry crude but generill1y carry refined products. Many
tankers belong to the major oil companies, with their ships carry-
ing their OWIl brand l1imlC of refined products. The majority nre
owned b)I independent operators who charter their ships.
Tankers call and do carr)' other liquid cargoes besides POL
(petroleum, oils, lubricants), including various chemicals and even
A highly sophisticated type of tanker is the liquefied natural gas
wine. The Illost specialized types of tankers arc the fiqucjierilllltlf- (LNG) carrier, like the SS EI Paso Southern shown here. They carry
0
ral g(/S (LNG) alld liqllefied peirolelllll gns (I.PG) (mTiers. These are natural gas liquefied at _260 Fahrenheit.
sophisticated and expensive ships designed to carry natural gas
and other forms of petroleum gases in a liquid state at extremely
forty or more to around twenty over the last decade, and may ulti-
high pressures and low temperatures.
mately shrink to under half a dozen as more automated ship tech-
nology becomes available in the coming years.
Once oftloaded) containers can be placed easily aboard semi-
truck trailers or railroad natcars for efficient transport overland
to their destinations. This ability makes possible sea-land bridge
freight transportation operations that have made international
trade far less dependent on str;:llegic waterwa),s like the Panama
Canal.
Roll-all roll-oh-(lioRo) ships have ramps and large hold open-
ings designed to accommodate either containerized or unitized
cargoes, or wheeled and tracked vehicles. In contrast to the con ~
tainership, this type of ship requires few facilities ashore-merely it
strong ramp from pier to ship, compatible with the mobile cargo.

Tankers comprise the largest segment of the active U.S. merchant
marine and are the most numerous ships on the high seas.

J\llodern inlermocia/ ships are designed to interface seamlesslr
with modes of inland transportation slIch as trucks, tmins, or
inland waterways. Containerships have revolutionized waterborne
freight transport worldwide, They are the most productive inter-
modal ships in the U.S. nmritime service. The larger ones can cruise
at 33 kllots alld calT)' sOllle 8,000 prepackaged20-foot-equivalellt-
uilit (TEV) colltaillers. Eveillarger capacity 10,000 to 20,000 TEV
containerships are now being designed. The standard size of the
containers plus their inherent security greatly enhance both ease
of handling ilnd protection against pilferage. A large containership
can be oflloaded and reloaded in less than twenty-four hours by
only about ten longshoremen (cargo handlers) using semiauto-
The containership SS Hawaiian Enterprise of Matson Navigation
matic cargo-handling equipment, instead of the eighty-plus long- Lines. One of the intermodal ship types, containerships are among
shoremen required to load and unload conventional freighters in the most efficient ships in the maritime service. Ships like this one
can carry over a thousand preloaded containers that are loaded
the past. Moreover, containership crew sizes have decreased from
aboard by special cranes,