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From: plains!umn-cs!LOCAL!thornley@uunet.UU.NET (David H. Thornley)
Newsgroups: sci.military
Subject: Re: Definitions of naval vessel types?
Message-ID: <1991May7.062421.12611@amd.com>
Date: 4 May 91 17:53:51 GMT
References: <1991May4.020831.19998@amd.com>
Sender: military@amd.com
Organization: University of Minnesota, Minneapolis, CSci dept.
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From: plains!umn-cs!LOCAL!thornley@uunet.UU.NET (David H. Thornley)


>(Summary of ship types deleted, more accurate information substituted.)
From the end of WWI, the primary warship types were DD (destroyer),
CL (light cruiser), CA (heavy cruiser), BB (battleship), CV
(carrier), and SS (submarine).  The heavy cruisers that served in
WWII were originally classified as light cruisers, but were
reclassified after the old armored cruisers had been retired and
the London naval treaty established two classes of the old light
cruisers.

At the end of WWI, the Navy finished a batch of destroyers of about
1100 tons with 4" guns, and had a lot of difficulty getting money
from Congress to buy new destroyers.  The first newer ones were built
in the late 20s, displaced about 1400 tons, and mounted 5" guns.
Building destroyers continued at a leisurely pace until war became
imminent.  Many of the older destroyers had been scrapped or converted,
and 50 of them were sent to Britain to be used as convoy escorts, and
so it was much easier to get funding for improved destroyers.  The
Fletcher class, possibly the most important wartime class, displaced
2050 tons and mounted five 5" guns; the largest U.S. destroyers of
the war were the 2400 ton Gearing class.

The light cruisers left from WWI were about 8000 tons with 6" guns;
the later ones were about 10,000 tons with more 6" guns, except
for the anti-aircraft cruisers, about 6000 tons with 5" guns.  These
were not intended for combat with other cruisers, but could be
effective against destroyers.  The light cruiser line culminated
with the Roanoke class, about 15000 tons with twelve automatic
6" guns, and no obvious mission.  U.S. prewar heavy cruisers were
9000-10,000 tons, with nine or ten 8" guns.  During the war, the
Baltimore class of about 13,500 tons was built; the Salem class
(about 17,000 tons, nine automatic 8" guns) was the culmination
of the gun cruiser in the USN.  Along with the rest of the heavy
gun ships, these cruisers were largely dead ends in development.

What happened in WWII is that aircraft took over the traditional
cruiser roles of exercising sea control and scouting.  Cruisers were
generally turned into carrier escorts, providing anti-aircraft fire
and protection in the unlikely event of surface combat.  Since the
main threat to merchant shipping became the submarine, destroyers
and small, slow carriers (CVEs) took over convoy duty, along with
new cheap and slow ships, of which the most effective were the
larger variety, called destroyer escorts (DEs).  At about this time,
the British introduced smaller escort vessels called "frigates" for
no immediately obvious reason, since the "frigate" of sailing-ship
days was actually a cruiser.

After WWII, submarines and aircraft improved drastically, to the point
that the battleship was rendered obsolete in its traditional role.
Surface warships were divided into carrier task force ships and
convoy escort ships, to speak very generally.  Large gun ships were
generally irrelevant in either role, and mostly served as shore
bombardment ships in this period.  Therefore, development of 
surface ships concentrated on destroyers and smaller vessels.  The
United States originally called its larger and more powerful
destroyers "frigates", a more appropriate use of the term, but
eventually, with the decline and scrapping of old gun cruisers,
called these ships "cruisers" and their smaller escort ships "frigates",
bringing USN terminology into line with the rest of the world.

Therefore, the major surface combatants of today all descend from WWII
destroyers (I of course except the ones that were built before 1950),
and terminology is still a bit messy.  To answer the originally posted
question, whether there is a clear definition of "frigate", "destroyer",
and "cruiser", the answer is "not really".

DHT

[42 lines quoting entire former posting deleted.  --CDR]