A Brief History of the Fleet Submarine
Fleet type diesel-electric submarines of the Balao Class were constructed during WWII from 1941 to 1946 in a number of U.S shipyards. The majority, however, were built at either the Electric Boat Company, New London, Connecticut or the Portsmouth Naval Shipyard, Kittery, Maine. Most of those which remained in commission, following the conclusion of hostilities, underwent so-called GUPPY conversions during the late 1940s and early 1950s. The acronym GUPPY stands for Greater Underwater Propulsion Power. Boats of this design had a 1" thick high-tensile strength (HTS) steel pressure hull and could operate at a test depth of approximately 400 feet. However, war records show that some of these boats exceeded this depth limit by as much as 100% while evading Japanese depth charge attacks. That they survived these depths is testament to their design safety factor. Boats of this type could carry enough fuel to travel approximately 16,000 nautical miles @ 10 knots.
Toward the end of WWII, as larger targets in the Pacific theater became increasingly scarce, many U.S. submarines were fitted with main guns (mostly 5"-25s) mounted on their forward and or after main decks and were used to attack lightly armed merchant vessels. These weapons were employed because smaller merchant ships were deemed to be unworthy of expending expensive torpedoes. In the years following WWII, deck guns were removed as they had little application in modern submarine warfare. This also eliminated the need to carry Gunners Mates, ammunition for the guns, and other related equipment needed to service those weapons. As well, valuable interior space used to store these items was freed for other uses. Several hull openings were also eliminated.
GUPPY conversions added snorkeling capability, additional battery capacity and hull streamlining such as enclosing the periscope shears in a streamlined fairwater, also known as the sail. In GUPPY II conversions, the pressure hull remained essentially un-altered, however, the free flooding superstructures were modified significantly to reduce submerged frictional drag. Also, bows were streamlined to provide better ship handling characteristics, especially in rough weather, and the bridge was given the protection of a plexiglass windshield. With the GUPPY III conversions, a fifteen-foot hull section was inserted between the Control Room and the Forward Battery compartments to accommodate a more advanced sonar system known as PUFFS, a forerunner of modern phased-array sonar systems. As well, the GUPPY III was capable of employing the Mk 45 nuclear torpedo. It is important to understand that these improvements and innovations were an ongoing response to the cold war and an attempt to better equip U.S. diesel-electric submarines. However, budget considerations prohibited each and every submarine from receiving all of these improvements and thus the greatest number of these were GUPPY IIs.
Of course, during the late 50s and 60s, as our nuclear submarine navy came of age, these and other technological improvements in sonar, communications, electric counter measures (ECM) equipment and much improved torpedoes gave these boats a viable and robust combat capability.
Other than the above, submarines of this vintage retained the same exterior dimensions: 312 feet in length and 24 feet at the beam. When surfaced and at diving trim and when fully fueled and with a full weapons load of 24 torpedoes, these vessels displaced approximately 1,800 tons with a draft of 16.5 feet. In this condition, roughly 60% of the vessel is below the surface. Most of the visible topside superstructure is free-flooding and does not contribute to buoyancy of the vessel.
Fleet boats were armed with 6 - 21" diameter torpedo tubes forward and four identical tubes aft. E.B. boats were equipped with four General Motors Model 278a, V-16, 1,600 HP @ 750 RPM, 2-cycle diesel engines. Portsmouth boats were equipped with equivalent Fairbanks-Morse 38D opposed piston diesel engines. Each engine drove a General Electric 1,124 Kw generator that supplied power to two electric main motors for propulsion and or to the four lead-acid storage batteries that provided power when submerged. The control of the engines, main motors and associated power distribution was controlled via the electrical cubical in the Maneuvering Room, which lay just forward of the after Torpedo Room, and which housed the main electric motors.
When surfaced, ballast tanks filled with air, which surround most of the ship's pressure hull, provide the ship with positive buoyancy. When diving, this air was vented and water rushed in to fill the tanks through flood openings in the bottom of the tanks. The ship would then assume a negative buoyancy and begin to submerge. At that time, all hull openings would be closed, the engines shut down and the ship's interior made watertight.
Upon diving, the Officer of the Deck and the two topside lookouts "clear the bridge" on the O.D.'s order and descend down through the upper conning tower hatch, through the Conn and on down into the Control Room. There, the lookouts take up stations on the bow and stern planes and the O.D. becomes the Diving Officer. The bow planes are hydraulically rigged out and the positioning of those planes then controls the ship's depth. In a similar manner, stern planes, which remain permanently extended, act to control the ship's upward or downward angle.
In passing down through the conning tower, the O.D. transfers navigational control of the ship to the Conning Officer who at Battle Stations would be the ship's captain.
Meanwhile, upon hearing two blasts on the diving claxton, the Chief of the Watch pulls open the levers on the hydraulic manifold which control the main ballast tank vent valves, causing air to vent from the tanks and allowing water to enter and flood the tanks. The ship quickly assumes a negative buoyancy. The Chief also closes the Main Induction valve which supplies combustion air to the engine rooms as well as fresh air to ventilate the ship. As the dive commences, the Chief of the Watch closely watches the indicator lights on the TP & TR panels which show the position of all hull openings and, when appropriate, "sings out" to the Diving Officer that he has a "green board" indicating a normal dive. If he does not have a green board by the time the ship reaches a keel depth of 34 feet, the Chief will shut the vents as a precautionary measure and advise the Diving Officer of same. At this time, the Diving Officer must quickly make a decision to continue the dive or execute an emergency surface.
The entire operation, from the sounding of the diving claxton until the uppermost part of the sail disappears from sight beneath the water's surface, takes place in just a little under one minute. This coordinated evolution must take place with flawless precision. The participants fully understand that anything less than perfect execution is simply not an option.
To a first-time visitor to the control room, the noises and shouted commands and their acknowledgements during the diving evolution might seem to be a chaotic, even scary, event. But this is a very carefully orchestrated evolution carried out by consummate professionals who have rehearsed this procedure many, many times. Every command that is given by the Diving Officer is repeated by the person it is intended for. This serves to assure that everyone involved is on the same page and knows exactly how events are proceeding.
When submerged, all of the ship's diving and trim functions are controlled internally by watch standers assigned to watch stations in the Control Room. There, along with the Chief of the Watch, the two Planesmen, an Auxilaryman and a Trim Manifold Operator, the Diving Officer oversees trim control and has full responsibility for maintaining depth control. Upon approaching ordered depth, the Diving Officer orders the negative tank to be blown to a predetermined mark. At that time, the ship should achieve neutral buoyancy. The Diving Officer also directs trimming of the ship by flooding from sea, pumping water into, out of or between internal variable ballast tanks to maintain the ship in an even trim as the crew move about the ship and seawater temperature and its attendant density change.
In today's modern nuclear powered submarines, the crash dive technique practiced on the earlier fleet boats has been replaced with a much more methodical and deliberate diving evolution. Nuclear submarines are true submersibles and when on patrol seldom venture to the surface more that to extend a periscope or communication mast. Unlike their predecessors, when at sea, these vessels are designed to remain submerged indefinitely following their initial dive.
Beginning in the mid 1960s, many diesel-electric fleet boats were sold or given to foreign countries allied with the U.S. Countries which received these boats included: Argentina, Brazil, Chile, Greece, Italy, Netherlands, Pakistan, Spain, Turkey and Venezuela. Before being signed over to the navies of these countries, the boats normally underwent a complete yard overhaul, which included a main battery replacement. Each boat then participated in an extensive training period to acquaint and educate the new officers and crew with the correct procedures to safely operate the vessel. Other boats of this class were expended as targets after they were stricken from the Navy list and a few were scuttled in the littoral waters of the U.S. to create reefs for the purpose of attracting fish. Many were simply sold for scrap and cut up.
By 1975, the last of the Balao Class GUPPYs had been retired from active service and the submarine force became an all nuclear fleet, with the exception of several Barbel Class diesel-electric boats which were stricken from the Navy list within the next decade. Today, only one diesel boat remains in commission, the USS Dolphin (AGSS-555). Sometimes referred to as the "Nickel Boat," Dolphin was built in 1968 and is a one-of-a-kind experimental boat. Measuring 165 feet in length, her hull is constructed of the then new HY-80 steel. Although now equipped with no torpedo tubes, Dolphin is capable of achieving depths in the range of 3,000 feet according to Naval Historian, Norman Polmar, in "The 'Nickel Boat' Keeps Going, and Going..." Proceedings (March) 2006, pp. 24-25.
A number of the fleet submarines remain today as museums in cities around the country. Many of these boats had served as reserve training vessels following their active duty service and thus escaped - at least for the near term - the scrap yard. Many of these WWII veterans have extraordinary combat records but that, in and of itself, was rarely enough to save them from the cutting torch.
In comparison with today's modern nuclear fast attack submarines, these venerable old warhorses are fairly crude. However, in the early part of the WWII, when the outcome was far from certain, they carried the war in the Pacific theater to the Japanese when no other branch of our military had such a capability. Today, few Americans know what a remarkable record these boats and their magnificent crews racked up in the Pacific.
With just under 2% of the U.S. Navy's personnel, U.S. submarines sank roughly a third of the Imperial Japanese Navy's warships and over 5 million tons of enemy merchant shipping. They literally strangled the Japanese war effort by wiping out Japan's merchant marine shipping capability. Despite a frenzied building effort, by the war's end Japan had less than 20% of her merchant fleet in operation. Without the ability to re-supply her Pacific island conquests, Japan's ability to control the Pacific was doomed. However, in the process of denying Japan's re-supply effort, U.S. submarines paid a very heavy price. In fact, no other branch of any of the U.S. military services suffered such a high percentage of losses during the war. 52 American submarines were lost to hostile action during WWII. Captured submarine POWs were treated extremely harshly by their Japanese captors in retribution for the heavy toll they took on Japanese shipping.
So, in the future,
if you should tour one of these proud old rusting veterans, remember that
it was the men who sailed them which made these ships the devastatingly
effective weapons platforms they were and which helped carry the day for
America more than sixty years ago. When the chips were down, these brave
men put it all on the line and dramatically turned the tide. Our nation
truly owes these fearless naval warriors its gratitude for their sacrifice.
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This page last updated: October 11, 2007