Destroyer escort

General description

Full-sized destroyers must be able to steam as fast or faster than cruisers and fast capital ships such as fleet carriers. This typically requires a speed of 25 - 28-40mph) (dependent upon the era and navy). They must carry torpedoes and a smaller caliber of naval guns to use against enemy ships, anti-aircraft guns, and antisubmarine detection equipment and weapons. While these requirements made the destroyer a fast all-around combatant, this made them too valuable to be relegated to convoy escort duties.

A destroyer escort needed only to be able to maneuver relative to a slow convoy (which in World War II would travel at 10 to), be able to defend against aircraft, and detect, pursue, and attack submarines. These lower requirements greatly reduce the size, cost, and crew required for the destroyer escort. Destroyer escorts were optimized for antisubmarine warfare, having a tighter turning radius and more specialized armament (such as the forward-firing Hedgehog mortar) than fleet destroyers. The slower speed of destroyer escorts was not a liability in this context as sonar was useless at speeds over 20 kn.

As an alternative to geared steam-turbine propulsion found in sloops of similar purpose, size and speed (as well as full-sized destroyers and larger warships), many US destroyer escorts of the World War II period had diesel-electric or turboelectric drive, in which the engine rooms functioned as power stations supplying current to electric motors sited close to the propellers. Electric drive was selected because it does not need gearboxes (produced on special precise machining tooling available in limited quantities, which were heavily in demand for the fast fleet destroyers) to adjust engine speed to the much lower optimal speed for the propellers. The current from the engine room can be used equally well for other purposes, and after the war, many destroyer escorts were re-used as floating power stations for coastal cities in Latin America under programs funded by the World Bank.. ships were the exception to this and they used a geared diesel engine to drive the propellers directly. s used the typical boiler and geared turbine propulsion system.

Destroyer escorts were also useful for coastal antisubmarine and radar picket ship duty. During World War II, seven destroyer escorts (DEs) were converted to radar picket destroyer escorts (DERs), supplementing radar picket destroyers. Although these were relegated to secondary roles after the war, in the mid-1950s, 36 more DEs were converted to DERs, serving as such until 1960–1965. Their mission was to extend the Distant Early Warning Line on both coasts, in conjunction with 16 s, which were converted Liberty ships.

During World War II, some 95 destroyer escorts were converted by the US to high-speed transports (APDs). This involved adding an extra deck which allowed space for about 10 officers and 150 men. Two large davits were also installed, one on either side of the ship, from which landing craft (LCVPs) could be launched.

Origins

The Lend-Lease Act was passed into law in the United States in March 1941, enabling the United Kingdom to procure merchant ships, warships, munitions, and other materiel from the US, to help with the war effort. This enabled the UK to commission the US to design, build, and supply an escort vessel that was suitable for antisubmarine warfare in deep open-ocean situations, which they did in June 1941. Captain E.L. Cochrane of the American Bureau of Shipping came up with a design which was known as the British destroyer escort (BDE). The BDE designation was retained by the first six destroyer escorts transferred to the United Kingdom (BDE 1, 2, 3, 4, 12, and 46); of the initial order of 50, these were the only ones the Royal Navy received, the rest being reclassified as destroyer escorts on 25 January 1943 and taken over by the United States Navy.

When the United States entered the war, and found they also required an antisubmarine warfare ship and that the destroyer escort fitted their needs perfectly, a system of rationing was put in place whereby out of every five destroyer escorts completed, four would be allocated to the U.S. Navy and one to the Royal Navy.

Alternatives

Destroyer escorts were designed and built to naval construction standards, and as such could only be built at yards experienced with naval standards. The United States Maritime Commission created its S2-S2-AQ1 design – which was based on the British-designed River class – for much the same role but using civilian construction standards. These ships would be classed by the Navy as the Tacoma class frigates (PF). These frigates had a greater range than the superficially similar destroyer escorts, but the US Navy viewed them as decidedly inferior in all other respects. The Tacoma class had a much larger turning circle than destroyer escorts, lacked sufficient ventilation for warm-weather operations (a reflection of their original British design and its emphasis on operations in the colder North Atlantic Ocean), were criticized as far too hot below decks, and, because of the mercantile style of their hulls, had far less resistance to underwater explosions than ships built to naval standards like the destroyer escorts.Gardiner, Robert, ed., Conway's All the World's Fighting Ships 1922–1946, New York: Mayflower Books, 1980, , pp. 148–149.

Post–World War II U.S. ship reclassification

After World War II, new-build United States Navy destroyer escorts were referred to as ocean escorts, but retained the hull classification symbol DE. However, other navies, most notably those of NATO countries and the USSR, followed different naming conventions for this type of ship, which resulted in some confusion. To remedy this problem, the 1975 ship reclassification declared ocean escorts (and by extension, destroyer escorts) as frigates (FF). This brought the USN's nomenclature more in line with NATO, and made comparing ship types with the Soviet Union easier. As of 2006, no plans existed for future frigates for the US Navy. and the littoral combat ship (LCS) were the main ship types planned in this area. However, by 2017 the Navy had reversed course, and put out a Request For Proposals (RFP) for a new frigate class, temporarily designated FFG(X). One major problem with ship classification is whether to base it on a ship's role (such as escort or air defense), or on its size (such as displacement). One example of this ambiguity is the air-defense ship class, which is classified as cruiser, though it uses the same hull as the s.

Vietnam War

During the Vietnam War, the Republic of Vietnam Navy received two s from the United States.

US Navy destroyer escort classes

World War II shipbuilding programs

total ships in the table: 507DEs + 56APDs

37 Buckleys listed here as Buckleys were converted to APDs after having been commissioned as destroyer escorts. All APDs listed in the table were completed as conversions. Captains were converted before commissioning as DEs.

Data from "Ship's Data U.S. Naval Vessels"

hull numbers for WGT and FMR are still incomplete, price of $2,157 for Brown/WGT DE-423 is assumed to be a typo

other classes missing (work in progress)

From the same document, List of Naval Vessels, pp. 11:

''Captain''-class frigates of the Royal Navy

Main article: Captain-class frigate

The Captain class was a designation given to 78 frigates of the Royal Navy, constructed in the United States, launched in 1942–1943 and delivered to the United Kingdom under the provisions of the Lend-Lease agreement (under which the United States supplied the United Kingdom and other Allied nations with materiel between 1941 and 1945), they were drawn from two subclasses of the destroyer escort (originally British destroyer escort) classification: 32 from the Evarts subclass and 46 from the Buckley subclass. Upon reaching the UK, the ships were substantially modified by the Royal Navy, including removal of torpedo tubes, making them distinct from the US Navy destroyer escort ships.

Captain-class frigates acted in the roles of convoy escorts, antisubmarine warfare vessels, coastal forces control frigates and headquarters ships for the Normandy landings. During the course of World War II, this class participated in the sinking of at least 34 German submarines and a number of other hostile craft with 15 of the 78 Captain-class frigates being either sunk or written off as a constructive total loss.

In the postwar period, all of the surviving Captain-class frigates except one (HMS Hotham) were returned to the US Navy before the end of 1947 to reduce the amount payable under the provisions of the Lend-Lease agreement; the last such frigate was returned to United States custody in March 1956.

Free French

Six Cannon-class destroyer escorts were built for the Free French Navy. Although initially transferred under the Lend-Lease Act, these ships were permanently transferred under the Mutual Defense Assistance Program (MDAP).

• FFL Algérien (F-1), ex-Cronin (DE-107)
• FFL Sénégalais (F-2), ex-Corbestier (DE-106)
• FFL Somali (F-3), ex-Somali (DE-111)
• FFL Hova (F-4), ex-Hova (DE-110)
• FFL Marocain (F-5), ex-Marocain (DE-109)
• FFL Tunisien (F-6), ex-Crosley (DE-108)

Mutual Defense Assistance Program – Post WWII

Under the MDAP the destroyer escorts leased to the Free French were permanently transferred to the French Navy. In addition, the following navies also acquired DEs:

Republic of China Navy (Taiwan)

:DE-47, DE-6

French Navy

:DE-1007, DE-1008, DE-1009, DE-1010, DE-1011, DE-1012, DE-1013, DE-1016, DE-1017, DE-1018, DE1019

Hellenic Navy

: DE-173, DE-766, DE-768, DE-193

Italian Navy

:DE-1020, DE-1031

Japanese Maritime Self-Defense Force

:DE-168, DE-169

Philippine Navy

:DE-168, DE-169, DE-170, DE-770, DE-771, DE-251, DE-637

Portuguese Navy

:DE-509, DE-1032, DE-1039, DE-1042, DE-1046

Republic of Korea Navy

:DE-770, DE-771

Royal Navy

DE-574DE-574 was originally provided to the United Kingdom under the Lend-Lease (Public Law 77-11) scheme, DE-574 was returned to the US custody under the provisions of the Lend-Lease scheme on the 25 April 1952 and simultaneously transferred back to the United Kingdom under the Mutual Defence Assistance Program.

Royal Netherlands Navy

:USS Burrows (DE-105), USS Rinehart (DE-196), USS Gustafson (DE-182), USS O'Neill (DE-188), USS Eisner (DE-192), USS Stern (DE-187)

Royal Thai Navy

:DE-746

National Navy of Uruguay

:DE-166, DE-189,

Comparison with contemporary frigates

The table below compares destroyer escorts and frigates designed for similar missions.

Surviving destroyer escorts

Four destroyer escorts are preserved as museum ships, while others remain in active service.

• The is preserved in Galveston, Texas.
• The is preserved in Albany, New York.
• The BNS Bauru (BE-4), formerly is preserved in Rio de Janeiro, Brazil.
• The modified , ARC Cordoba (DT-15), formerly is preserved in Tocancipa, Colombia.
• The HTMS Pin Klao (DE-1), formerly , was decommissioned from the Royal Thai Navy on 30 September 2025. She was the last of World War II era destroyer escort active in any navy. Her fate is yet to be determined.
• The Japanese Maritime Self-Defense Force operates six s.

References

1. Blackman, pp. 393 & 394
2. Potter & Nimitz, p. 550
3. Cooney, pp. 6 & 7
4. NAVPERS, pp. 32 & 35
5. Friedman, Destroyers, pp 230–232
6. Friedman, Small Combatants
7. Silverstone, pp. 153–157
8. Silverstone, pp. 157–163
9. Silverstone, pp. 164–167
10. Silverstone, pp. 167–170
11. Silverstone, pp. 163 & 164
12. Silverstone, pp. 170–175
13. Blackman, p. 458
14. Blackman, p. 457
15. Blackman, p. 456
16. rapid-fire version using an auto-loading mechanism to insert the shell into the breech
17. Blackman, p. 455
18. Blackman, p. 452
19. Blackman, p. 453
20. (1946). "Alphabetic Listing of Major War Supply Contracts: Cumulative June 1940 Through September 1945". Civilian production administration, Industrial statistics division.
21. Silverstone, pp. 153–175 & 276–280
22. Ship's Data, U.S. Naval Vessels, DE data tables
23. Lenton & Colledge, pp. 245–247
24. Morison, Samuel Eliot. (1962). "History of United States Naval Operations in World War II". Little, Brown and Company.
25. "Ships' Data -- U.S. Naval Vessels - BuShips".
26. Lenton & Colledge, p. 225
27. Watts, pp. 225–239
28. Silverstone, p. 246
29. Lenton & Colledge, p. 232
30. Blackman, p. 114
31. Blackman, p. 354
32. Blackman, p. 44
33. Blackman, p. 199
34. Blackman, p. 353
35. Blackman, p. 113
36. Blackman, p. 624
37. Blackman, p. 356
38. Blackman, p. 183
39. Blackman, p. 355
40. Blackman, p. 8
41. Blackman, p. 43
42. Blackman, p. 351
43. Blackman, p. 127
44. Blackman, p. 21
45. Blackman, p. 198
46. Blackman, p. 350
47. Blackman, p. 182
48. Blackman, p. 79
49. Blackman, p. 348
50. Blackman, p. 240
51. Blackman, p. 78
52. Blackman, p. 229
53. Blackman, p. 167