CVB-41 USS Shiloh as completed (Note: drawing contains some parts taken from Shipbucket.com)
|Displacement (Standard)||45,000 tons|
|Displacement (Full Load)||56,000 tons|
|Performance||Speed (max)||33 knots|
|Armament||Aircraft (1947)||32 FV-4, 32 F4U, 48 AD, 16 F7F, 4 AD1W|
The CVB-41 class vessels (then unnamed) were originally conceived in 1940 as a design study to determine the effect of including an armored flight deck on a carrier the size of the Essex class. The resulting calculations showed that the effect would be disastrous for air group size. The resulting ship would have a maximum air group of 45, compared to 90-100 for the standard Essex class fleet carriers. As a result, the concept went to finding a larger carrier which could support both deck armor and a sufficiently large air group. Unlike the Royal Navy's aircraft carriers, for which the armored deck was part of the ship structure, the Midway class retained their "strength deck" at the hangar deck level and the armored flight deck was part of the superstructure. The weight-savings needed to armor the flight deck was acquired by removing a planned cruiser-caliber battery of 8-inch (203 mm) guns and reducing the 5-inch antiaircraft battery from dual to single mounts. The resulting carriers were very large, with the ability to accommodate more planes than any other carrier in the US fleet (30-40 more aircraft than the Essex class).
President Roosevelt was not in favor of this class and tried to have construction aborted in favor of additional CV-9 class carriers. He had much opposition from the Navy in this and the first group of six ships was built as planned. However, a proposed second group of six ships was rejected in favor of six additional CV-9 class ships (bringing that class to 32 ships). However, after the death of President Roosevelt during the 1944 election campaign and the subsequent election of President Dewey, those six additional CV-9 class ships were cancelled and replaced by the second batch of CVBs,. Finally, a 13th CVB was ordered in 1947 to replace the sunken Shiloh. Although the first ship to be ordered was the CVB-41 Shiloh, the first ship to be commissioned was the CVB-43 Gettysburg and it is after that ship the class was named.
President Roosevelt may well have been right in his misgivings, in the short term at least. In their original configuration, the Midway class ships had an airwing of almost 130 aircraft. Unfortunately, it was soon realized that so many planes was beyond the effective command and control ability of one ship. While the resulting ships featured excellent protection and unprecedented airwing size, they also had several undesirable characteristics. Internally, the ships were very cramped and crowded. Freeboard was unusually low for such large carriers. In heavy seas, they shipped large amounts of water and corkscrewed in a manner that hampered landing operations. The first three ships had been designed with the smallest possible island and this feature caused severe complaints due to the cramped comamnd facilities in provided. Ironically, the island size had been kept down due to complaints that the deck space occupied by the island and flight deck guns on the CV-9 Essex class was excessive. The second three of the first batch and the whole of the second group were completed with larger islands. CVB-42 and CVB-43 were refitted with the larger island but CVB-41 was sunk while still fitted with the small island.
The ships also had very heavy anti-aircraft batteries but these proved to be disappointing. Director facilities were limited and the 5 inch L54 guns were inferior anti-aircraft weapons compared to the 5 inch L38. Overall, the CVBs were considered to have much inferior anti-aircraft batteries to the CV-9s, a major factor in the loss of the Shiloh. After the sinking of that ship, the damage control facilities of the class were considered wanting and, during their first major reconstruction, these were much improved with extra pumping capability, improved fire-fighting equipment and much more emergency electrical generating capacity.
The Reconstruction Program
The CVB-43 Gettysburg class deck plan changes. The top picture is of the ships (except Appomattox) as built, the center picture shows the ships following their first reconstruction (Appomattox being built to this configuration) while the bottom picture shows the final deck plan of the ships. (Source: United States Navy)
The First Reconstruction (1952 - 1959)
USS Gettysburg after first reconstruction (Note: drawing contains some parts taken from Shipbucket.com)
At the end of the Second World War, the United States Navy was by far the most powerful navy on Earth and a cggod case could be made that its size and combat power exceeded that of all the other (surviving) navies of the world put together. The Navy deployed 39 fleet carriers, 100 escort carriers (with a total embarked aircraft strength of 3,744 and 3,200 aircraft respectively), 26 battleships, 6 large cruisers, 40 heavy cruisers, 66 light cruisers, 560 destroyers, 230 destroyer escorts and over 200 submarines. While the need to confront the Japanese in the Pacific was still extant, the fleet obviously needed rationalization and reduction to the level that a peacetime establishment could support. There was much pressure in the navy to retain the surplus ships in reserve but this was rejected on the grounds that any future war would, as far as the United States was concerned, be nuclear and last only as long as it took to utterly destroy the enemy. The war would be fought with what the U.S. had, not with what it could mobilize from the reserve fleet. The result was a deluge of surplus ships descending on the scrapyards. All pre-war construction was scrapped within five years of the end of the war and the wartime construction was severely pruned.
The exception to this was the aircraft carriers. The six surviving pre-war carriers (Lexington, Saratoga, Ranger, Wasp, Yorktown and Hornet) were kept in the fleet through to the mid-1950s to cover the gap while the Essex and Gettysburg class ships were rebuilt. By the end of the Second World War, it was becoming apparent that increasing aircraft weights made the traditional launching practices impractical and that, in future, catapult assisted launches would be the norm. In addition, the introduction of an angled deck (first tried out on the Saratoga with both Lexington and Saratoga being equipped with an early version of the angled deck by 1947) greatly eased aircraft handling and operations. Finally, the batsman who had controlled landings on U.S. Navy carriers for decades was partially replaced by a new "mirror landing sight". This was the result of an intelligence report that Japanese carriers had such equipment and included photographs of the system. The U.S. Navy reverse engineered it from that basis.
The first reconstruction of the Gettysburg class was extensive. The entire bow section was rebuilt with the hull plating carried up to the flight deck to give a totally enclosed bow. This bow section was equipped with two catapults of a new type that drew its power directly from steam generated by the ship's boilers. The bow elevator was enlarged and reshaped to handle larger aircraft. The midships section and stern of the flight deck were rebuilt to include and angled deck with a third steam catapult being installed in the ship's waist. The aft elevator (the site of the explosion that had turned Shiloh's condition from moderate damage to critical, was removed and replaced by a starboard-side deck edge elevator. The ship's island was further enlarged and re-arranged with a mast installed aft to carry extra radar equipment. Perhaps ironically considering the sinking of the Shiloh, the anti-aircraft armament was drastically reduced. A detailed examination of the sinking had shown that the ship's anti-aircraft firepower had been virtually ineffective and that it had actually compromised the most effective defense of the ship, her fighter aircraft. Furthermore, a detailed examination of the damage control logs had shown that the critical factor in her sinking had been the explosion of the ship's forward five-inch magazines. So, it was argued, the provision of a heavy anti-aircraft battery was not only of questionable value but it had actually endangered the ship. Accordingly, most of the guns were removed, the five inch L54 battery being reduced to four guns while the three inch battery was removed completely. The magazine spaces for those guns were converted to other uses, significantly reducing congestion on board.
The last of the CVB-43 class, USS Appomattox was modified under construction and completed to this design. The other eleven ships came in over the next seven years, each reconstruction taking an average of 26 months (the longest taking 30 months and the shortest 22 months. As the first six ships rejoined the fleet in their modernized configuration, the old pre-war U.S. carriers were decommissioned and scrapped (the USS Lexington being preserved as a museum ship in Charleston, South Carolina by a fortuitous coincidence, the volume of ships being scrapped was so great that she spent several years waiting her turn and this allowed a group of South Carolina ship enthusiasts to organize her preservation). By the middle of 1959 all 12 CVB-43 ships had been rebuilt to the new standards.
Second Reconstruction 1968 - 1974
USS Seven Pines after second reconstruction (Note: drawing contains some parts taken from Shipbucket.com
While the first reconstruction had modernized the basic CVB-43 design, there were numerous shortcomings with the ship. Flight deck area was still too small for the latest generation of aircraft while the position of the port deck-edge elevator meant it was only useful when neither landing nor take-off operations were being conducted. Since the forward centerline elevator could not be used when flying off aircraft, this reduced the ships to the starboard deck-edge elevator. Accordingly, the ships were modernized with a new and much enlarged flight deck, the port deck edge elevator was moved aft and the forward centerline elevator was removed completely. A new starboard deck-edge elevator was installed forward of the bridge As a result, the operational flow of aircraft was much improved. The waist catapult was removed and two much more powerful bow catapults installed. The bridge was enlarged yet again and a new radar suite was installed. The extra topweight involved was such that stability was dangerously reduced and the ships were bulged to restore stability margins to a safe level. Unfortunately, this exagerrated the ship's tendancy to roll and pitch.
Due to age and short remaining life, the first five of the CVB-43 class were not rebuilt to the new standard and only the last seven saw service in their final form.
|CVB-41||Shiloh||1942||1942||1944||1945||Sunk by German air attack June 6, 1947|
|CVB-42||Bull Run||1942||1942||1944||1946||Decommissioned and scrapped 1975|
|CVB-43||Gettysburg||1942||1942||1944||1945||Decommissioned and scrapped 1974|
|CVB-44||Chickamauga||1943||1943||1945||1946||Decommissioned and scrapped 1976|
|CVB-54||Malvern Hill||1943||1943||1945||1946||Decommissioned and scrapped 1977|
|CVB-55||Sharpsburg||1943||1943||1945||1946||Decommissioned and scrapped 1978|
|CVB-56||Chancellorville||1944||1944||1946||1947||Decommissioned and scrapped 1982|
|CVB-57||Fredericksburg||1944||1944||1946||1947||Decommissioned and scrapped 1983|
|CVB-58||Seven Pines||1944||1944||1946||1947||Decommissioned and scrapped 1984|
|CVB-59||Manassas||1944||1945||1947||1948||Decommissioned and scrapped 1985|
|CVB-60||Murfreesburo||1944||1945||1947||1949||Decommissioned and scrapped 1986|
|CVB-61||Spotsylvania||1944||1945||1948||1951||Decommissioned and scrapped 1987|
|CVB-62||Appomattox||1947||1948||1951||1953||Decommissioned and scrapped 1988|