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The CGBL – a Product Improved Version of the CG 52
Philip Sims
ABSTRACT
There are indications that the next
cruiser design will be a large ship, both
in dimensions and displacement. It will
inevitably be compared to the existing
cruisers of the CG 47 class. The CG 47
class was a mod-repeat of the DD 963
class and carried over many “big
destroyer” legacies such as an aluminum
superstructure and a compensated fuel
system. The mod-repeat ships had
extremely limited service life reserves.
In the mid-1980s, the Navy desired to
evaluate future technologies for future
ships but using the CG 47 as a starting
point invoked that ship’s inherent
features which often confused the
evaluation. For example, fitting a
composite superstructure showed little
change over an aluminum superstructure
ship although the Navy policy was not to
use aluminum but steel in the future. A
composite superstructure would show
weight savings over a steel
superstructure ship. A modern features
CG was needed to evaluate future
technologies so a 1986 study created the
CG Base Line (CGBL). It was a
“product improved” version of the VLS
variants of the CG 47 class (CG 52
onward) with full design margins, full
service life reserves, clean ballast fuel
system and all electric auxiliaries.
Military mission improvements included
radar cross section reduction, a steel
superstructure with increased fragment
protection, and a Collective Protection
System. The changes increased the
dimensions of the ship to a waterline
length of 620 feet, a beam of 69 feet and
a full load displacement of 13,675 tons.
Since the combat system (over half the
cost of the ship) and the main machinery
was unchanged, the cost increase was
much less than the size increase would
indicate. The major increase in
displacement was due to a low-cost-perton steel superstructure and features that
could reduce cost such as combat system
modularity and generous internal volume
easing construction. The resulting ship
was more survivable, faster, had much
better seakeeping and could accept a
major mid-life modernization. The
paper describes the ship impact of each
of the changed features. The size of the
DDG 1000 and the CG(X) alternatives
are easier to explain if compared to the
CGBL rather than the CG 52.
INTRODUCTION
In order to conduct a Congressionally
requested Alternative Propulsion Study,
a series of baseline future ships were
created. One concept was a Medium
Surface Combatant whose study baseline
(Medium size, Fossil fuel, Mechanical
drive = MFM-1) had a 721 foot length
on the waterline, an 82 ft beam and it
displaced 21,260 long tons [Reference
1]. The illustrations in Ref 1 show a
flush deck hull and a twin tower
superstructure configuration [Figure 1].
Figure 1: MFM-1 – a nominal future
surface combatant.
The ship study was fitted with a very
high powered radar, 157 large missile
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cells and a 155 mm Advanced Gun
System along with substantial ASW,
aviation and light gun armament. While
not specifically a CG(X) alternative, the
2006 MFM-1 represents a “peek ahead”
at the large combat system ships which
the CG(X) Analysis of Alternatives
would have to evaluate. The MFM-1’s
21,260 tons displacement often draws
the comment from people who see it for
the first time that it is “twice as big as
CG 52”. Other variants of that ship in
Reference 1 are even larger in
displacement. In comparing ships by
ratioing their displacements, you have a
numerator and a denominator. This
paper is about whether the denominator
which first comes to mind, the 9,500 ton
CG 52, is the right ship to compare to a
future large surface combatant.
REPLACEMENT OF THE
OFFENSIVE SURFACE
COMBATANT BY THE CARRIER
The date of the replacement of
surface combatants by aircraft carriers as
the dominant naval weapon has been
claimed by different writers as having
occurred at one of several events. Some
credit the sinking of the Repulse and
Prince of Wales. Others point to the
Battle of Santa Cruise where neither
surface fleet saw the other, while some
think the inflection point was the pivotal
battle of Midway. However, there were
brutal surface combatant battles at night
off Guadalcanal where airplanes played
only a supporting role before or after.
No aircraft were involved in the
December 1944 Duke of York’s sinking
of the Gneisenau in 1944 in an Artic
gale.
The final displacement of the surface
combatant as a Navy important fighting
force did not occur until the large
Midway class carriers with radar
equipped aircraft arrived after WWII.
The very large ship meant that
operations in bad weather’s high sea
states was possible. Fitting carrier
aircraft with radar meant the ability to
attack the enemy ships in bad weather
and at night (and finding one own ship
upon return) was now possible. The
surface combatant had lost even its
primary fighting role in night and bad
weather. The mission of the surface
combatant was now as a carrier escort.
THE EARLY SUPER CARRIER
ESCORTS
Muir [Reference 2] describes the
effect on the surface force of becoming
dedicated to the escort mission, Some
classes, the DD 930s and DDG 2s, found
a role of escorting the still numerous
Essex class carriers but the future of the
Navy escort force was seen as centered
on the super carriers of the Forrestal
class onward. The all-weather nuclearbomber-armed super carriers needed
escorts that could keep up with them.
The DLG 9 class was found to be a bit
small to keep up with long and heavy big
carriers. The first large class of super
carrier escorts, the DLG 16 class
Destroyer Leaders shown in Figure 2, set
the pattern for the ship type – around
500 feet long, an 80,000 horsepower
propulsion plant and a displacement of at
least 7,000 tons. Those features allowed
an escort to keep up with a super carrier.
Being a dedicated escort drove a certain
kind of design logic since there was no
such thing as a wounded escort – a
damaged ship was a hole in the screen
and it was better that the ship drop out
and the screen reform with intact ships.
Thus it was acceptable to have relatively
unarmored ship with the survivability
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emphasis being on saving the crew and
the hull. Retention of partial combat
capability was not a priority because it
had little value for a pure escort. The
US Navy evolved the “big destroyer”
through the DLG 26 class and several
nuclear alternatives.
what the DD 963 would have been if it
had been upgraded to its intended DDG
configuration.
Figure 3: The as-delivered ASW
destroyer DD 963 (NS).
Figure 2: The DLG 16 class was designed
as a super carrier escort (NS).
While current design emphasizes
reducing signatures, it should be
remembered that an artifact of the “save
the carrier” escort era was the
installation of some ships of the ULQ-5
S-band blip-enhancer which was
intended to have escort give radar
returns resembling that of a carrier to
confuse enemy targeting. [ Reference 3].
THE DIRECT ANCESTORS OF
THE CG 47 CLASS
Friedman [Reference 4] and Potter
[Reference 5] provided extensive
material on the creation of the DD 963
class. The as-delivered ASW
destroyers, Figure 3, were intended to be
modernized and converted to antiaircraft guided missile armed ships.
Except that they were not fitted with a
lightweight 8 inch gun forward, the DD
993 class, Figure 4, were essentially
Figure 4: The intended upgrade of the
ASW destroyer to an anti-air DDG would
have resembled the DD 993 class (NS).
THE CG 47 CLASS
The ships that became known as the
CG 47 class went through their design
and, in the case of the lead ship, keel
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laying as DDGs [Figure 5]. The rather
convoluted relationship between DD,
DDG and CG hull numbers and
designators is described in Appendix A.
Figure 5: All of the design documents for
the CG 47 describe her as the DDG 47
Staiman [Reference 6] provides a
history of the process of fitting Aegis to
the DD 963 hull and then fitting the
Vertical Launching System (VLS) to CG
52 onward. A relevant question is if,
during the design phase, it was ever
considered to make the hull larger. After
the CG 47 came in heavier than
expected, the use of a forty foot “plugand-slide” hull lengthening was
considered to get back buoyancy and
hull volume. The concept of plug-andslide is an attempt to reconcile the desire
to reuse engineering drawings with the
fact that the best place to change the
lines and the best place to add volume do
not coincide. Another complication is
the USN length based damage criteria
which a simple plug places the
bulkheads in the wrong location for an
assumed longer damaged area.
As shown in Figure 6, the proposed
plug-and-slide hull change resulted in
three major groupings of the ship hull
compartments. Ends of the ship were
the existing lines and the existing
compartments making for a high
drawing reuse. The middle of the ship
had a section of old compartments and
the new lines where the plug was to be
inserted and forward of that where
existing lines were pushed ahead. The
overall compartment drawings were to
be retained but the drawings of anything
connected to the shell had to be changed.
The area of greatest change was the new
volume within the old lines. Since
length drives bending moment, all the
midships structural scantling drawings
would have had to be changed.
The decision was made not to add
buoyancy but to remove weight in the
follow ships with the Take Off Tons
Sensibly (TOTS) program described by
Staiman.
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Figure 6: A 40 foot lengthening of later CG 47s, using the plug-and-slide approach,
was considered.
signature, carrier the value of signature
control became greatly increased. The CG
52 onward had a revolutionary combat
system but, as mod-repeat ships, the basic
nature of the hull was not changed to match
that combat system.
THE TRANSFORMATIONAL
CRUISER
The fitting of VLS to the CG 52 made
that ship into what would later become
fashionable to call a ‘transformational”
weapons system. The Russians had installed
a limited number of large cruise missiles on
their ship earlier but the miniaturized jet
engine and folding wings of a Tomahawk
missile allowed fitting an extremely large
number in a compact launching system.
The surface combatant had acquired an
ability it never had before of conducting a
far inland strike or to attack other ships at a
range of 100s of miles away.
Capability of independent action changes
a surface combatant’s basic design logic.
There is such thing as a wounded cruise
missile ship. It may have lost a mission
area or speed but, due to the missiles’ selfguiding after launch nature, the wounded
ship can still play an important role over
100s of miles. For such a ship, changing the
design to be able to “fight hurt” becomes
very useful. No longer operating in consort
with the large dimension, hence large
THE TECHNOLOGY ASSESSMENT
PROCESS
A person develops a new idea – it can be
a technology or an improved design standard
- to resolve a chronic fleet problem. The
obvious questions are 1) what does it cost?
and 2) what are the benefits? If the new
concept is large enough in volume, manning,
weight or center of gravity to affect the size
of the ship (either up or down), a major part
of the cost question is resizing the ship. If
the performance benefits are altered
depending on where the baseline system is
located on ship, future and not just existing
locations have to be addressed.
The process is to define the new idea and
analyze it when applied to the baseline ship
in a ship synthesis model such as the Navy’s
Advanced Ship System Evaluation Tool
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(ASSET) which can resize the ship. It is
helpful in explaining the results to people
familiar with ships but outside the design
community to use a familiar baseline ship to
eliminate time in defining the baseline. In
the mid-1980s the DDG 51 was still a paper
ship and the CG 52 was considered the
exemplar of a modern surface combatant. It
was also a large surface combatant class
which would have to be replaced far enough
in the future for technologies to successfully
go through the long development process.
fair to assess stabilizing device technology
on such a baseline which would reward fins
(provide a lot of motions relief with small
size system) and punish Frahm tanks system
(basically unacceptable due its free surface)?
A more typical moderate value metacentric
height ship would be a fairer baseline to
assess motions control systems.
As part of the mod-repeat philosophy, the
lines of DD 963 class were retained even
though the following classes were much
heavier. Seawater responds not to lines but
the hole in the water. The nearly 10,000 ton
hole in the water for the CG 52 is much
different than the designed 7,800 ton DD
963 hole in the water although the lines of
both ships are identical. Pushing the lines
deeper in the water resulted in the shift of
the centers of buoyancy and water plane
farther aft. If one looks carefully at pictures
of the CGs released by the Navy [Figure 8],
one notices a very slight nose down attitude
due to that shift. It could only be partially
compensated by locating the needed lead
ballast aft. Having a bit of a nose down trim
does not harm the operations of the ship, but
raises the question of its suitability as a
starting point to compare to proposed future
alternative lines.
PROBLEMS WITH THE CG 52 AS A
BASELINE
The CG 52 has several significant
problems when asked to serve as a
technology analysis baseline some of which
came from her large carrier escort pedigree.
If one wanted to assess the value of a
composite superstructure, the replacement of
the CG’s lightweight aluminum
superstructure would show little change.
However, the policy at the time was not to
use aluminum superstructures for the larger
surface combatants. Thus, to show any
possible benefits of a composite
superstructure, it would be necessary to
compare it to a steel superstructure which
would be otherwise fitted to a future cruiser.
If an advocate wished to propose new
armor for the Combat Information Center, it
would make a difference if it were in the
traditional carrier escort above-the-weatherdeck location or in the hull as in the DDG 51
class.
Other ship specific features come from
the CG 52’s mod-repeat design history. The
class has a small metacentric height (GM)
but a long righting arm to achieve
satisfactory stability. This means the ship
takes on a considerable roll in a high speed
turn, as if Figure 7. If any weights are off
center, a low GM ship has a tendency to take
on a noticeable calm water list. Would it be
Figure 7: CG 53 rolls in a high-speed
turn. (N)
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Figure 8: CG 61 shows the very slightly nose down inclination of her weather deck edge. (N)
by 20 men to match the Ship Manning
Document.
The CG 52 80,000 horsepower
propulsion plant and electrical generators
supplying steam from waste heat were
replaced by a plant modeled on that of the
DDG 51. The new machinery provided
100,000 horsepower for propulsion and had
4 generators, without waste heat recovery, to
make it an all electric ship.
The fuel storage system was changed from
a compensated ballast system to a noncompensated fuel system with clean ballast
tanks.
The deckhouse material was changed
from aluminum to steel. It featured
substantial anti-fragment armor and
increased nuclear blast resistance.
THE CGBL UPGRADES
Starting with a CG 52 match run in
ASSET, it was changed into a new design
ship by adding full design and construction
margins plus service life reserves. They
were applied to weight, center of gravity
(KG), electric load, hull powering and
accommodations as described in Table 1. If
the modeled ship had been actually intended
for construction with an existing (hence low
risk) combat system, the margins would
have been much lower. Since it was
intended to evaluate technology as if it were
being fitted onto a totally new design, totally
new ship margins were used.
This being before the Smart Ship
program, the ship’s manning was increased
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Table 1: Generic Margins and Service Life Reserves
Design
Margin
10 percent
8 Percent
Light ship Weight
Light ship Center of Gravity rise
Full Load Displacement
Full load Center of Gravity rise
Electric Load
Air Conditioning Load
Internal Arrangement Area
Accommodations
Drag in Speed-Power Calculation
Hull Girder Stress
20 percent
20 percent
5 percent
Service
Life Reserves
10 percent
1 ft
20 percent
20 percent
10 percent
8 percent
1 ton per square inch
The topside was shaped like that of the
DDG 51 [Figure 9] to reduce Radar Cross
Section. Another added survivability
features was a Collective Protection System.
A possible future cruiser feature, not
found on the DDG, was installation of a
small secondary Combat Information Center
and a small communications space aft to
ensure Tomahawk launch capability even if
the main rooms were damaged. Berthing
for a DESRON flag space was fitted to the
ship
Although the combat system was the
same as the CG 52, several components
were to be installed in modules. The two
guns were in modules and so was the
helicopter hangar. This would allow
construction and testing outside the shipyard
and, in the future, facilitate their
replacement by newer weapons. The
CGBL bow gun is located further aft than on
the CG 52 in order to fit the width of the
modular box within the converging bow
lines. The aft gun is located further forward
to fit the depth of the modular box within
the rising keel line.
To improve speed and seakeeping, the
hull was lengthened and the hull
coefficients optimized. The hull was of a
flush deck configuration in order to increase
reserve buoyancy aft and eliminate the
inherent structural weak point of a sudden
hull depth change.
Figure 9; The not-yet-built but under design
DDG 51 was the source of many features used
by the CGBL.(N)
The overall result was a strike capable
cruiser designed to DDG 51 standards and
technology or better. Adding these features
increased the weight and dimensions of the
ship as described in Table 2.
Figure 10 shows an outboard profile of
the CGBL.
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Table 2: Displacement and Dimension Growth due to Various Features
Start is CG 52 Match
Changes:
SMD Ship
New Design Margins and
Service Life Reserves
New Uprated Machinery
Modular Combat Systems
Steel SS
Non-Comp
Increase Survivability
Speed and Seakeeping
Sum:- - - - - - - - - - - - - - - - Result is the CGBL:
LBP, ft
529
Beam, ft
55.4
---
+.1
+4.7
-+31
---+60
-----620
-0.2
+0.5
+1.9
+5.7
+0.5
-2.2
-----69.0
Disp Full Load, LT
9,420
+65
+1,240
+50
+605
+535
+375
+685
+700
-------------13,675
Speed, kts
29.7
-.1
-1.4
+1.8
+0.5
-0.3
-0.4
-0.3
+1.0
-------30.5
Figure 10: CGBL profile
part of a pair created at the same time with
the sister painting being that of the Mission
Essential Unit (MEU) concept of a hybrid
cruiser-carrier. In the pre-computer graphics
era, painting a portrait is how two
dimensional engineering drawings were
converted into a three dimensional view of
the new concept. Incidentally, the mid-
THE CBGL PAINTING
The head of the NAVSEA Preliminary
Design division, George Kerr, desired to
highlight the division’s ability to produce
new concepts, so noted marine and aviation
artist Richard Allison was paid to create an
oil painting of the CGBL [Figure 11]. It is
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1980s date of the painting is revealed by the
DDG 51 in the background having a nearly
vertical lattice mast instead of the final
design’s inclined tripod.
In the
Figure 11: The CGBL painting
unchanged, except for the addition of the
secondary CIC, regardless of hull changes
In fact, the modular installation of the guns
and aviation facilities was intended to
reduce combat system construction and
installation cost although increasing ship
weight due to module boundaries.
A steel superstructure weighs twice as
much as an aluminum but the metal is half
the cost and easier to weld. It is a weight
increase without a cost increase. Also as
part of the “steel is cheap” philosophy,
generous deck heights were used to ease
assembly.
THE CGBL EVALUATED
The CGBL showed a major increase in
displacement but the combat system had
remained the same as the CG 52 and, as
shown in Figure 12, from reference 7, the
combat system is at least 50% of the cost of
the ship. Figure 12 shows that, while the
platform part of the ship has a learning curve
over time, the payload part of the ship had a
countervailing improvement curve. The
ships with the Block IV version of the
combat system had 60% of the ship in
payload and 40% was platform. Thus for a
CGBL using a CG combat system, 50-60%
of the cost from the CG remained
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growth assigned to various modern features
added onto the existing ship.
Figure 12: CG payload and platform cost
percentages.
Figure 13: The DDG 1000 is a very large
destroyer. How can its size be explained
to the public?
Many features such armor, the Collective
Protection System, hull and superstructure
shaping increase ship’s cost but have direct
military value.
The long length adds weight but with the
improved hull coefficients, the ship is faster,
and a much better seakeeper.
If a modern features CG 52 is nearly
14,000 tons, the DDG 1000 and CG(X) are
not as great of a growth as it appears when
compared to the actual big-destroyer-legacy
and mod-repeat CG 52.
THE CGBL COMPARED TO
CURRENT CONCEPTS
CONCLUSIONS
The obvious question is what is the value
of a paper about a mid-1980s math model of
a cruiser to today’s shipbuilding effort? The
DDG 1000, Figure 13, has a 14,600 ton
displacement making much larger than any
previous DDG and larger than the CG 52.
How can the Navy explain the size of the
DDG 1000 and the upcoming CG(X) to the
public? One can ‘build down’ by starting
with the new ship design and remove feature
by feature to make it smaller but that process
involves divulging a great deal of design
information about those new ships. The
alternative is to “build up” by starting with a
well known ship, in this case the CG 52, and
add features to explore which ones are
making the ship larger. This paper presents
such a build up approach with weight
The 1986 CG Base Line (CGBL) was a
mathematical model of a cruiser with
modern features needed to evaluate future
technologies. One reason for the need of a
new baseline was many of the features of the
CG 47 class can be traced back to her “big
destroyer” heritage. In fact, the lead ship
was called the DDG 47 all the way through
the keel laying of the first ship. The big
destroyer legacies included an aluminum
superstructure, CIC above the weather deck
and a compensated fuel system. The CG 47
was designed with the philosophy of the
ship being a mid-life modernization at
delivery which meant the ships had
extremely limited service life reserves. The
VLS versions of the class, the CG 52
onward, were loaded up with additional
weapons. Using a match run mathematical
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model of the CG 52 as a starting point for
technology studies invoked that ship’s
inherent features and mod-repeat design
choices. These legacies often confused
results of the evaluation of technologies for
future cruisers.
The CGBL was a “product improved”
version of the CG 52 created with the
ASSET ship synthesis model. It had full
design margins, full service life reserves,
clean ballast fuel system and all-electric
auxiliaries. Military mission improvements
included radar cross section reduction, a
steel superstructure with increased fragment
protection, and a Collective Protection
System which increased the displacement
considerably. The math model of the ship
was used for several years to conduct
technology evaluations such as composite
superstructures and new machinery. As the
DDG 51 class became the most well known
ship in the fleet, that class became the
preferred baseline for technology studies
and the use of the CGBL declined.
The CGBL is of historical interest now as
a “missing generation” of a transitional type
that could have been built in between the
CG 52 class and the DDG 1000 and the
CG(X). It has been noted that those two
ships are predicted to be much larger than
the in-service cruisers. However, the CGBL
had dimensions of a waterline length of 620
feet, a beam of 69 feet and a full load
displacement of 13,675 tons. The size of
the DDG 1000 and the CG(X) alternatives
are easier to explain if compared to the
CGBL rather than the CG 52.
Conference and Expo, November, 2007.
Fort Lauderdale, FL
2) Muir, Malcom, Jr., Black Shoes and Blue
Water: Surface Warfare in the United States
Navy 1945-1975, (Naval Historical Center,
Washington, DC 1996).
3) Friedman, Norman, World Naval
Weapons System 1991/92, (Naval Institute
Press, Annapolis, Maryland 1991), pg 533.
4) Friedman, Norman, U.S. Destroyers; An
Illustrated Design History, (Naval Institute
Press, Annapolis, Maryland 1982), pg 298.
5) Potter, Capt. Michael C., Electronic
Greyhounds: The Spruance-Class
Destroyers, (Naval Institute Press,
Annapolis, Maryland 1995), pg 49.
6) Staiman, Robert C., “Aegis Cruiser
Weight Reduction and Control”, Naval
Engineers Journal, May 1987, pg 190.
7) Johnston, John and Mathai, Cathy,
“Where The SCN $ Go: An Affordability
Focus”, Association of Scientist and
Engineers, 28th Annual Technical
Symposium, 1991. pg 6.
Photo Credits:
N = US Navy
NS = Navsource Web Page
Philip Sims graduated from Webb Institute in
1971 and went to work for the Naval Ship
Engineering Center. He was part of the FFG 7
design team in 1972. From 1973 to 1975, he
performed aircraft carrier design studies for the
Sea Based Air Study and CVV design. He
received a master’s degree from MIT in 1976.
The 1977-80 period was spent conducting
design studies for the CGN 42, the reserve FFX,
and the DDX (later DDG 51) projects. From
1981-83, he was the naval architect on the BB
References
1) Webster, James S., Fireman, Howard,
Allen, Dillon A., MacKenna, Adrian, and
Hootman, John C., “Alternative Propulsion
Methods for Surface Combatants and
Amphibious Warfare Ships,” presented at the
2007 SNAME Maritime Technology
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62 reactivation and Ship Design Manager for the
BB 61 and CA 134.
He was member of the NATO Staff
Requirements Working Group for the NATO
Frigate Replacement for the 1990s (NFR 90).
The early 1990s were spent on CGN, DDG 993
and CG 47 modernization studies. He prepared
destroyer/frigate studies as part of the Force
Architecture phase of SC 21. In 1999, he started
conducting the first pre-milestone A studies of
JCC(X) and stayed with the program until the
cancellation in 2003. He performed the DDG 51
conversion and mod-repeat studies for the
CG(X) Analysis of Alternatives. He is
currently conducting Comparative Naval
Architecture and LCC(R) studies.
hull number instead of taking the next AGF
hull number. An example of a name change
of an in-service ship was the change of the
DDG 5 from being the Biddle to being the
Claude V. Ricketts in 1964.
When the CG 47 carried her DDG hull
number into the CG list, it left a gap in
cruiser numbering system. It has claimed by
outside observers that CG 43-46 hull
numbers were reserved for follow-on hulls
of the cancelled CGN 42 but that is not the
case. When the USN builds ships as part of
the Foreign Military Sales process, they are
given USN hull numbers during the
construction process. For example, the
DDG 25 was the USN building hull number
for the ship that became the Australian
Navy’s D-38 HMAS Perth. The four ships
built for the pre-revolutionary Iranian Navy
were assigned US DD designators and hull
numbers during construction. When
purchased by the USN, they should have
been redesignated as DDGs because of their
long range AAW missile armament. The
Navy had intended them to be DDG 47-50
so it reserved that block of numbers for the
four ships. Once again, the administrative
pain of the massive documentation changes
required if a hull number was revised made
that undesirable so they ended up with a
DDG designators but retained their
destroyer hull numbers. When a new design
DDG class came along, those reservations
made the DDG 51 the next available hull
number. This convoluted history is why so
many of the CG 47 and DDG 51 hull
numbers overlap.
APPENDIX A: THE RELATIONSHIP
BETWEEN DD, DDG AND CG HULL
NUMBERS AND DESIGNATORS
The ten ships of the DLG 9 class were
reclassified as the DDG 37 class instead of
joining the larger DLGs as being
redesignated as CGs. The last of those ships
was the former DLG 15, the Preble, which
became the DDG 46. Thus the next
available DDG number was 47. The ships
that became known as the CG 47 class went
through their design and, in the case of the
lead ship, the keel laying as DDGs. When it
was decided to redesignate the lead ship as a
CG, it was too difficult to change all the
documents to the next available cruiser hull
number which was CG 43.
In many ways, the hull number is more of
a ship’s permanent identifier rather than its
type designator or even its name, both of
which have been changed on USN ships
while leaving the number the same. An
example of a retained hull number is the
command ship conversion of the AGF 11,
the Coronado, which kept its original LPD
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