Diesel Fast Attack Submarines

USS Tang (SS563) USS Trigger (SS564) USS Wahoo (SS565)
USS Trout (SS566) USS Gudgeon (SS 567) USS Harder (SS 568)
USS Darter (SS 576)
Gone But Not Forgotten


by Jim Christley (updated 1998)
It was 1945, the war was just over and most of the Naval Submarine Force was wanting to go home and be done with the boats. There was an air of contentment that the force had won the war by strangling the sea lanes around Japan and causing the downfall of the Empire. That was certainly unarguable. There was a sense of well being in that the American fleet submarine was as good as a submarine needed to be for all those who would challenge the US Navy. That unfortunately was soon to change. The fleet submarine was obsolete and even though it would exist for another 20 years, it was as useful in the new submarine world as a biplane was at the beginning of World War II. Useful enough, if the opponent had only the same thing.

The fleet boat had a problem. It was slow. Fast enough on the surface, when submerged it could do nearly six knots but only for an hour. That meant it could run for a distance of only six nautical miles. At a slower speed, say three knots, it could run for maybe 10 hours, a distance of thirty nautical miles. A destroyer could easily circle above it for days. With the advances in sonars the surface ships had, the fleet boat could be killed with an ease the Japanese Imperial Navy could only dream of. The lone fleet boat could still harass a convoy or kill a few escorts, but the newly organized fast surface battle groups were a threat to be reckoned with. Fortunately, the US Navy was the only force that possessed fast surface battle groups.

The trigger that started the revolution in submarine design and construction was a German submarine designated as the Type XXI. Nearly 60 feet shorter than the Tench-class American submarine, the Type XXI had two things the US boat needed. The first was high underwater speed and the second was a snorkel. The boat was being built in 1944 and 1945 in a Germany which was being heavily bombed and overrun by Allied forces. In January 1945, the German shipbuilding industry was making a Type XXI operational every 28 hours. There weren't enough crews and the training time required meant that very few if any Type XXI's made offensive patrols in the Atlantic or North Sea. When the war ended, many of the boats were trashed, but many were taken by the allied powers for study and use. What we found while testing the U-2513 and U-3008 was shocking. The Type XXI could dive to nearly 650 feet, had a crew of only 57, had a 6-tube bow nest and a decent reload capacity and most shocking off all, she was really fast. In a state three sea, the boat could out run a destroyer by heading into the sea and remaining submerged. The boat could snorkel 10,000 miles at 12 knots. The boat could hit 15 knots in short sprints and could maintain over 6 knots for nearly 40 hours at 300 feet. That meant the Type XXI could outrun the active sonar tracking ability and the fire control systems of most ASW vessels. The German boat was also quieter at 6 knots than a Tench-class was at 2 knots.

These submarines could clearly attack a fast battle group with some good chance of success and might even take out a carrier. The Soviet Navy took nearly fifteen of these boats back to the homeland after the war. We had a problem. We needed a new submarine. One question that needed answering was whether only one design was needed or separate designs for separate missions. In August 1945 Commodore Merrill Comstock was ordered by CNO to conduct a study of WWII submarine experience. A questionnaire was circulated among submarine officers soliciting their views on submarine speed, depth, and other issues. The outcome of the General Board and Submarine Officer's conference was that a single design new attack submarine would be built starting in 1946 and that other existing vessels would be converted for specialized uses. The new design was formally started in February 1946.

 The designers called for a streamlined ship with few appendages. The bridge and masting support structure  was to be enclosed in a light faired structure which would become known as the sail. The old fleet boat open shears mast support structure contributed over 50% of the total resistance at high speed. All things that didn't have to stick out were made retractable (capstan, towing fairleads, cleats and the safety track), the deck guns were done away with in all forms. The resulting hull form was more efficient than the XXI. The circular section hull was chosen over the more radical figure 8 form of the German boat. The pressure hull was two feet wider than a Tench but one hundred feet shorter. To save space, a radical new engine was adopted.

The General Motors company had built a new lightweight compact engine that ran at a high speed. It was quite a bit different than the 16-268 and 16-278 the submarine crews were used to. Instead of the crankshaft being horizontal and the cylinders being arranged in two rows of eight each, this engine had a vertical crankshaft and the cylinders were arranged like a radial aircraft engine. These were the GM 16-338 "pancake" engines. The engine was a mere 13.5 feet from the base of the generator to the top of the air intake filter and 4 feet wide. It was a two cycle engine which developed 1090 bhp at 1600 rpm. On the top was an air intake then four layers of four cylinders each. Each cylinder had a six inch bore and a six and one half inch stroke. On the bottom of the crank shaft was an Elliot generator which developed 817 kW at a maximum of 710 volts DC. The whole engine, all up and loaded with fuel and oil weighed just over eight tons. Being just over 4 feet wide, the designers could pack four engines in an engine room only 22 feet long. This dropped an entire engine room from the submarine design.

More space and weight was saved by the elimination of four 21 inch diameter by 22 foot long torpedo tubes and the requirement for additional torpedo stowage of the long Mk 14, 16, and 18 torpedo. The initial design called for no tubes aft. The submarine officers however, lobbied hard for retention of the aft tube nest but settled for two tubes of 21" and a length of 15 feet. These would take the Mk-27 and the planned Mk 37 torpedo and were to be used as countermeasures weapons. Countermeasures were fired at pursuing ASW ships or other pursuing submarines. These tubes were new, they were simpler and were designed for swim out type torpedoes.

The tubes forward were all new. Instead of using a pulse of air behind the torpedo to push it out, the new tubes used a slug of water. There was a piston which had air on one side and water on the other. It worked kind of like a hypodermic needle. The piston was moved all the way aft with the forward end of the cylinder filling with water from the sea. The sea valve, called the barn door on some ships, was closed. To fire a torpedo, the tube was prepared as normal then when the firing signal was given, high pressure air was ported to the aft end of the piston. This pressurized the water in the piston. A slide valve with ports around the torpedo tube opened to allow the water from the piston to enter the aft end of the tube. This high pressure water forced the torpedo out. No air bubble and no poppet valving arrangement was needed. The new system made somewhat less noise than the air system, and is still in use on modern nuclear (and foreign nuc and non-nuc) submarines.

In October 1946, the design was finalized and two boats ordered. The first was to be USS Tang (SS-563) and was to be built at Portsmouth Naval Shipyard. The second was to be USS Trigger and was contracted to Groton in the Electric Boat yard. The boats were to become the Tang- class. The class was to be built at a length of 268 feet and a beam of 25 feet. With 2850 shaft horsepower on each of two shafts, the boat could do 17.5 knots at 700 feet. (at the one hour rate) or snorkel 10,000 nautical miles at 10 knots.

The next fiscal year (FY47) two more boats were ordered. They were to become USS Wahoo and USS Trout, (SS-565 and 566). Wahoo went to Portsmouth and Trout went to EB. The next set were split the same way the next year and were the USS Gudgeon and USS Harder (SS-567 and 568). The construction went well and boats were delivered on time. Trigger was delivered first. However, when the boats started to operate, there were problems. The engines they didn't work well.

Several reasons have been given for the failure of the pancake engine in submarine use. It was undoubtedly a combination of effects. The engines were supposedly to use a special lubricating oil. The Navy supposedly insisted on standard diesel lubricating oil and that adversely affected the bearings. This may have been the case or it may have been the lightness of the internal structures of the engines. They did leak oil into the generators and from information gained from people who worked on them, they were a real maintenance problem in the confined space of the engine room. Whatever the reasons the engines made advocates out of some and enemies of others. The Navy decided in 1956 to replace all the engines with the smaller, lightweight version of the 10-cylinder Fairbanks-Morse opposed piston engine. The boats had to be lengthened some 9 feet in the engine room to make enough space for the new engines, only three of which could be installed. Thus in 1957/58 each of the first four boats were stretched to 277 feet. Gudgeon and Harder were built to a length of 277 feet and with the FM engines as initial installation. In 1967, some of the boats got an additional 15 (some sources say 18) foot section added to receive the PUFFS installation and to give added room. These boats were the 563, 565, 567 (all the Portsmouth boats) and the 568.

At the same time as these boats were being built and used, the Guppy program was taking off. Other than the deeper depth capability of the Tangs, the Guppies were nearly as good and a whole lot cheaper. The nuclear propulsion plant in the Skipjack shaped hull made a quantum leap in submarine capabilities.

Comparison Item    Balao/Tench Class   Tang Class   Skipjack Class

 Length                   311.0'                        268.0'            252.0'
 Beam (PH)             27'(16)                      27'(18)          31.5'
 Disp. Subm.           2415                          2260             3500
 Speed Subm.           8.75(1hr)                 18(1hr)           29(unlimited)
 Endurance Subm.    48hrs/2kts                43hrs/3kts       2160hrs/29kts
                                                                                       90 days (due to food)
                                  96nmi                     129nmi           62,640nmi

Even though the Tang-class was seemingly left in the dust, it took its place alongside the Guppies performing the arduous duties of maintaining the watch on the Soviet fleet and training our Naval ASW forces and those of our allies. That is not to say the class wasn't worked hard. For example Tang was based in Pearl Harbor and in the period from July 1956 to 1972 she deployed seven times to the Western Pacific to operate with units of the Seventh Fleet or alone in areas assigned by the fleet commands. Each deployment lasted 6 to 7 months. That meant a deployment on average, once every 20 months (which does not take into consideration overhauls and other operations). During the Viet Nam War, she aided US Naval forces in and around the South China Sea and earned four battle stars. During the same period, she made trips from Pearl Harbor to the Northwest US and Canada to operate from the Naval Torpedo Station at Keyport, Washington as far west as the Aleutians. From 1972 to 1978 she operated in UNITAS XV and numerous deployments for training exercises. Tang was decommissioned and transferred to the Turkish Navy, renamed the Piri Reis (S-343): first as a lease arrangement in 1980, then purchased outright in 1987, decommissioned from the Turkish Navy on 13 August, 2004, now a Submarine Museum in Izmir Turkey.

Trigger, actually the first of the Tangs to see service, was initially home ported in New London. She made trips at and under the edge of the ice pack in conjunction with USS Nautilus (SSN-571) in 1957. She made a couple of Northern and Northern European trips to keep watch on the Kola Peninsula and to assist our allies in training their ASW forces. In 1959, she changed home port to Charleston and from that port made three Med trips until 1968 when she went into the shipyard for modernization and a hull lengthening. The newly overhauled Trigger changed home port to San Diego and operated out of Bangor Washington on several occasions as a MK 48 test ship. In 1972, she made her first WesPac from October of that year to March of 1973. Then in July of 1973, she was decommissioned and transferred to Italy where she served as the Livio Piomarta (S-515) until the Italian Navy put her out of commission and then scrapped.

Gudgeon was attached to SubRon 1 in Pearl initially where she reported in July 1953. In the next four years she made two WesPacs and had local ops. She took part in secret operations which are rumored to have included close monitoring of the Soviet port of Vladivostok. Taking on the flag of ComSubPac, Gudgeon sailed from Pearl Harbor on 8 July 1957. In the next 8 months, she operated with forces out of Yokosuka, Japan, Subic, transited through the Indian Ocean, and visited ports in Africa. The boat transited the Atlantic then after a trip of 25,000 miles, reentered Pearl again on 21 February 1958 becoming the first US submarine to circumnavigate the globe. More Wespacs were made in 1959, 1961 and 1963 after which she entered Mare Island Naval Shipyard to undergo the lengthing process mentioned above. Gudgeon served in the Pacific until she was decommissioned. Then in 1983, she was transferred by lease to Turkey and renamed the Hizir Reis (S-342). She was purchased in 1987. Decomissioned in 2003 now a submarine museum in the city of Izmit Turkey.

Harder operated out of New London after her commissioning. She made an historic test of the ability of a submarine to transit on the snorkel by making the trip from New London to the Bahamas snorkeling. In 1959, she participated in SUBICEX where the cruised some 280 miles under the Arctic Ice pack. Harder changed home port to Charleston late in 1959 and operated out of that port on Med trips, and extensive ASW operating exercises in the Atlantic and Caribbean. In 1967 the boat was modernized and lengthened. Harder was sold to Italy where she served as the Romeo Romei (S-516) until the Italian Navy put her out of commission and was then scrapped.

Wahoo joined the Pacific Fleet in Pearl Harbor in 1953. Her first WesPac was in 1954 then the next year she started her second. After extensive local ops and a short overhaul at the Pearl Harbor Naval Shipyard, she started another WesPac in October 1957 which included a visit to Tahiti. In 1959 she headed out again. From then until she changed home ports in June of 1971, Wahoo continued to meet commitments in the local area, western pacific and made extensive trips to the war zone off Vietnam where she earned three battle stars. It was during her involvement in the Viet Nam War where she performed patrol, insertion and extraction operations and other more sensitive work that application was made for the awarding of the War Patrol Pin for this service. The application as well as those by other boats who served at the time in combat was met with stubborn resistance on the part of Submarine Force veterans of WW II, many of whom were in senior positions, who reminded the applicants that unless the boat sank enemy shipping, it was not a successful patrol and didn't deserve a patrol pin. Thus none of the submarine crews of the force which made patrols during that conflict, some of which were longer and as arduous as World War II patrols were able to earn war patrol pins. Nor did boats that did similar service during the Korean war. The same situation is seen in the awarding of strategic deterrent patrol recognition to those who made  Regulus patrols.Wahoo was placed out of commission in 1980 and remained in Philadelphia at the shipyard in storage until the early 1990's when she was sold out for scrapping. All that remained at that time was a gutted hulk as most of the parts had been used to supply spares for the other boats in foreign service.

Trout has had the longest, if not always active, service career. Operating out of New London after her commissioning in 1952, Trout operated extensively with NATO units from the North Atlantic to the Caribbean. At one time she sailed under the ice for some 268 miles setting a record that was later bested by Harder. In 1959 she was assigned to SubRon 4 in Charleston where she underwent BuShips Shock tests. After an overhaul in 1963, Trout operated out of Charleston in local operations and three Med deployments. In 1970 the boat's home port was changed to San Diego where she made two WesPacs, one in 1972 and again in 1975. Her home port was changed to Philadelphia in 1976. She, along with Wahoo, was slated to be transferred to the Iranian Navy in 1979. Extensive overhauls were performed on both ships and Iranian crews underwent training in both Philadelphia and New London. When the Shah of Iran was replaced in 1979, the deal was put off and finally canceled. The boats, Trout and Wahoo were put in storage. Wahoo was used for parts replacement for other ships, Trout remained in Philadelphia in storage until 1994. In that year, she was taken out of storage and preparations were made to use the boat as a radio controlled test platform. As such, the boat would have been a controllable submerged target for our submarines to practice anti-submarine exercises against a quiet diesel submarine. It would also be used as a target to insure the ADCAP would perform against this type target as it is our mainstay torpedo. At present, the use of the boat is on hold. Until recently Trout has been at Pier two in Newport, RI but was towed to Key West. Trout was later towed to Philadelphia placed on the donation list for historic ships later removed from the list sold for scrap towed to Galviston and scrapped in 2008.

These boats rendered exemplary service. They spent as much if not more time at sea as did their contemporaries, either diesel or nuc. The appellation that is the title of this piece is absolutely untrue. The operations these boats performed are the stuff of legends, but under the cloak of Cold War secrecy and the cloud of World War II prejudices, they go unrecognized. There are unsubstantiated rumors of one or more of the boats penetrating harbors and rivers to gather intelligence and of hold-downs by foreign ships in and out of international waters. The boats made war patrols in combat and classified situations for which they and their crews have not received the proper recognition. As times change and the operations of the Cold War and Vietnam are declassified, researchers will be able to document the service of this class.

By the way, USS Darter (SS-576) is in a class of its own and, although a direct descendant of the Tang-class, is different. The reason for its inclusion in the rhyme used as the title is because she looked like a Tang, operated like a Tang and rhymed. Sunk as target 1/7/92




       USS TANG (SS563)

        USS TRIGGER (SS564)

        USS WAHOO (SS565)

     USS TROUT (SS566)

       USS GUDGEON (SS567)



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Rick Rowe