BAP Pacocha (SS-48)
Encyclopedia
BAP Pacocha (SS-48) was a submarine
of the Marina de Guerra Peruana (Peruvian Navy
) named for the 1877 Battle of Pacocha
, in which the Peruvian ironclad Huascar clashed with the Royal Navy
. Formerly , a Balao-class submarine
with a GUPPY IA upgrade, she had been sold to Peru
and commissioned
on 28 May 1974.
At 18:50 in the evening of 26 August 1988, Pacocha was transiting on the surface with the forward torpedo room and bridge hatches as well as the main induction valve open. Forty-nine men were aboard, including the Squadron Commander, to conduct an operational readiness inspection. About half an hour after sunset, ten minutes from Pachocha’s expected arrival at the port of Callao
, the 412 ton Japanese fishing trawler Kiowa Maru (also spelled Kyowa Maru and Hyowa Maru) rammed her in the aft port quarter. Kiowa Maru was equipped with an ice-breaker bow, with a sub-surface protrusion designed to penetrate and break apart what it struck. Pacocha sank quickly.
Four men died immediately in the collision and sinking: her commanding officer, Capitán de Fragata Daniel Nieva Rodríguez, died securing the bridge access hatch; Teniente Segundo Luis Roca Sara and two enlisted men were trapped in flooded compartments and drowned. Twenty-three of her crew succeeded in abandoning ship.
In the sinking submarine, Teniente Roger Cotrina Alvarado secured the watertight forward torpedo room door and attempted to pressurize the compartment. He then tried to secure the forward torpedo room hatch. Instead, however, he had to force the hatch open to free a sailor whose leg was caught in the hatch due to the 40 degree up angle the Pacocha assumed before sinking. As the Pacocha began to capsize water rushed into the compartment, washing lieutenant Cotrina down the ladder and fortunately, shortly afterwards, forcing the hatch door closed.
Cotrina credited this sequence of events to a miracle, testifying, “I saw a light and I experienced an ineffable power that allowed me to shut the hatch.” There is little doubt that if that hatch had not been shut, no one inside the submarine would have survived. Two commissions, one conducted by the Peruvian military, the other by the Vatican came to the conclusion that with the water pressure, it would have been technically impossible for anyone to close the hatch. As such the Roman Catholic Church
's Congregation for the Causes of the Saints authenticated the miracle. This is unusual, as normally miracles in the causes of saints, are those for cures believed by the Church to be through the saint's intercession, but in this case the declaration of a miracle was the obtaining of superhuman strength by someone in a disaster situation. On 6 June 2003, Pope John Paul II
celebrated Marija's beatification Mass ironically in the Croatian port city of Dubrovnik. Cotrina Alvarado received Holy Communion from the pope on this occasion, and afterwards gave him a small replica of the Pacocha as a memento.
Less than five minutes after the collision, Pachoca settled on the bottom at a depth of 140 feet (42.7 m) with a 9 degree up angle.
At 20:02, with Pachoca an hour overdue, the Peruvian Navy
declared an emergency. Boats were dispatched to search along Pacocha’s route. The tug Jennifer II was sent to rendezvous with Kiowa Maru and investigate. Some twenty minutes later, Contralmirante Guillermo Tirado, Commander of the Submarine Flotilla, arrived at the Callao Naval Base, assumed command, and dispatched the submarine BAP Dos de Mayo (SS-41) to search.
At 20:30, the survivors trapped in Pacocha released their messenger buoy and attempted to call aft compartments on the sound-powered telephone. There was no response.
By 21:00, the crew of Jennifer II had confirmed that Kiowa Maru had collided with something, and radioed their report to the base. While that report was in progress, the survivors in Pacocha fired a red distress flare. The Navy immediately issued a call for rescue and salvage divers to report for duty. Rescue of the survivors on the surface began at once, and within an hour and a half, twenty survivors and three bodies were drawn from the water. Three enlisted men had died of hypothermia
during the four hours they had spent in the 14 °C (57.2 °F) water.
Meanwhile, 22 survivors mustered in Pacocha’s forward torpedo room: four officers, four chiefs, and fourteen junior enlisted personnel. The senior officer transpired to be Cotrina. At 21:20 they fired another flare that led searchers to the messenger buoy at 21:31. Messenger buoys on Balao-class submarines
do not have telephones, so communication could not be established, but those on the surface did realize that the buoy and flares probably meant that someone was still alive. The survivors held training in the use of the Steinke hood
, with which most crewmen were unfamiliar. (The Peruvian Navy
, like the United States Navy
, had stopped in-water escape training from depth several years previously.)
At 22:50, the smell of chlorine
gas in main control prompted another assessment of the boat's condition. A vent valve was found that had not been tightly shut, and more water had seeped into the aft battery compartment. All lithium hydroxide
canisters were brought forward, and the survivors sealed themselves in the forward torpedo room. By 23:30, two canisters of lithium hydroxide
were opened and spread. The crew was put to bed.
By midnight on Saturday, 27 August 1988, all twenty survivors and three bodies had been brought ashore. Survivors were taken to the nearby Naval Hospital. Although all suffered from hypothermia
, none had significant injuries. At the scene, an assortment of vessels were on the surface including the submarine, Dos de Mayo, a torpedo retriever, a floating crane, and several small craft.
Locating divers during their off-duty hours was hampered by the lack of telephones in many of their homes, but by midnight, eight were at the scene in SCUBA gear
. Depth to the deck of the ship was between 125 feet (38.1 m) aft and 110 feet (33.5 m) forward, with the ship variably reported as having between a nine and fifteen degree up-angle. The first team of divers followed the messenger buoy's line, which had played out to a significant distance. Since it was not located directly over Pacocha, a second line was tended straight down to the sail. The divers tapped on the hull and received a response from the forward compartment of the boat. However, they were unfamiliar with the code used, so were unable to interpret the tapping.
At 00:40, Contralmirante Tirado called Captain Schillingsburg, the United States
Defense Attaché, to request rescue assistance from the United States Navy
.
By 01:00 the survivors had sent messages to the rescuers that they should be able to hold out for 48 hours. By 0200, three volunteers in Pacocha had donned oxygen breathing apparatuses
(OBAs) and walked through compartments as far aft as main control. The aft battery compartment had water over the deck, so it was not entered. Meanwhile, personnel ashore including several divers studied the salvage air connections on BAP La Pedrera (SS-49) (the former , also a GUPPY IA Balao-class submarine
) and discovered that they did not have appropriate salvage air hoses or fittings. Ultimately, Mark V diving system umbilicals were used with fittings manufactured during the night on two frigates. (Mark V diving hoses are negatively buoyant, ½-inch inner diameter, 600 psig (4.2 MPa) pressure rated hoses, MIL-H-2815.)
After two frustrating hours, improved communications with Pacocha were finally established at 02:27 using the signal ejector to pass written notes to the divers. Word was received at 0350 and passed to the survivors that the United States Navy
was sending its rescue system. However, over the next few hours the estimated time of arrival of the rescue system shifted steadily later.
Having had no communication from the surface for nearly two hours and unaware that there were currently no divers available, Pacocha fired another flare at 04:20. Yellow was picked so as not to give the impression that something new was seriously wrong—they only wanted to express concern that they had not heard anything in a couple of hours. However, at 04:40 a small electrical short and fire broke out in main control. It was brief and self-extinguishing, but renewed concern for the survivors' atmosphere. Only carbon dioxide
extinguishers were available for fire-fighting.
A new group of divers arrived on scene at about 05:00 after reviewing salvage connections, escape trunk configuration, and other details on La Pedrera. Shortly after the divers went to work, they recovered the body of Pacocha’s Commanding Officer, Capitán de Fragata Nieva, just inside the deck access door to the sail.
At 06:00 the survivors held reveille and prepared breakfast. Utilizing the signal ejector, communication was passed that the crew was in good spirits with enough air to last for seventy-eight hours based on calculations of available oxygen
and lithium hydroxide
. They also had adequate supplies of water, but no food after eating what little they had, including cake, for breakfast. While inspecting the submarine, the survivors noted a heavy black cloud rising from below the deck in the forward battery compartment. No one entered this compartment again. Two more canisters of lithium hydroxide
were opened and spread on the upper bunks. Later in the morning another four canisters were opened. Approximately twenty canisters were unopened. One eight cubic foot (230 L) oxygen
cylinder was bled into the compartment; three oxygen
cylinders were left unused.
Information on the use of the escape trunk and the Steinke hood
was passed from the surface. The crew was divided into five groups and one member from each group trained in the operation of the escape trunk. Groups were arranged by seniority, with one officer in four of the five groups, and by other factors such as swimming ability and self-confidence. Via message, Pacocha informed those on the surface that there were twenty-two survivors.
At 07:30 a message was sent to Pacocha informing them that the fly-away rescue system was on the way from the United States
. This provided a visible boost to morale among the crewmen, and all involved in the casualty planned to wait for that equipment.
However, by 09:50, the crew was becoming listless, agitated, and hyperventilating. The boat's only atmosphere monitoring equipment was aft in the flooded compartments, but the lithium hydroxide
did not seem to be working as well as expected. Cotrina was becoming concerned about the submarine's atmosphere. He spread four additional lithium hydroxide
canisters. To exacerbate the situation, their only light, the emergency light located at the bottom of the forward ladder, was periodically flickering on and off, and the beam from their only battle lantern was steadily growing weaker. Cotrina passed a message to the surface requesting guidance. Contralmirante Tirado instructed Cotrina to use his best judgment in decided when to escape. Cotrina consulted his crew; their recommendations to escape were unanimous with one exception. Teniente Lindley offered various reasons to wait, and if he had to escape, he wanted the divers to provide SCUBA tanks
since he had been trained in their use. Cotrina ordered him to join the first group of escapees.
At 11:30, divers completed connecting high and low salvage using Mark V diving umbilicals for hoses and the manufactured fittings. The high salvage was connected to air banks on the submarine BAP Abtao (SS-42)
, named after the Battle of Abtao
. These banks were charged by thirty-five-year-old, oil-lubricated compressors. There are no filters on the system, and air samples of the air banks had never been taken.
During escape training, crew members decided to inflate their Steinke hood
s in the compartment before entering the escape trunk, and to use them as flotation devices, but not to enclose their heads in the hoods. One member of the first group, Chief Monzon, did wear the hood. He was to be the third most seriously injured of the twenty-two escapees. After inflating the escape devices, four men entered the escape trunk and controlled flooding and pressurizing from inside the trunk. After the side access hatch was opened, the four men spent at least ten minutes arguing over who would exit first. Finally Teniente Gomez, the senior man, ducked under and began his ascent, followed in turn by Chief Monzon and Petty Officer Reyes. All three men reached the surface and were promptly rescued. However, within minutes of reaching the surface, they began suffering great pain in their joints, became disoriented and unsteady, experienced shortness of breath, and displayed symptoms of crepitus
.
The rescuers on the surface had been told to expect four men in the first group. Finding only three, they began to search for the missing Teniente Lindley. While they searched, the survivors drained and opened the escape trunk, where they found the teniente, alive and well, still in the escape trunk. Lindley reentered the submarine, and was added to the last escape group.
The second group, led by Teniente Nieri, completed their escape by 12:25 without incident, and were flown by helicopter to the recompression chamber. The helicopter flew low over the water, to keep the air pressure as high as possible.
Immediately after the second group surfaced, air was supplied through the high salvage connection. When the connection was opened aboard Pacocha, high-pressure seawater came from the line since it had not yet been blown dry. The survivors immediately shut the high salvage connection valve and never reopened it. The low salvage line was open to atmosphere on the surface, not pressurized, but was connected to the submarine below the level of water in the bilge. Thus, that line was filled with seawater to a depth equivalent to the pressure in the boat, and did not allow air flow.
All five of the survivors in the third escape group completed an uneventful escape by 12:40. However, after they left, the outer escape hatch could not be shut from inside the submarine, so when the crew attempted to drain the trunk, seawater continued to flood into the submarine until the valves were secured. After the problem was communicated to the surface, divers investigated, discovered that the hatch’s dogs were obstructing closure, and freed the obstruction with a large wrench.
The fourth escape group made an uneventful escape by 15:15. On reaching the surface at least one of them was transported to the shore recompression facility by helicopter. The fifth group then made an uneventful escape by 16:25. By this time, a recompression chamber was on scene on the floating crane along with two medical officers. All three in this escape group were recompressed within five minutes of surfacing.
After the fifth group left the escape trunk, divers placed a set of SCUBA bottles
in the trunk. The final three escapees spent between one-half and one hour breathing from the SCUBA bottles
before escaping at 18:05, by which time personnel topside were again becoming apprehensive. Divers were sent to investigate the delay and were present when all three escapees simultaneously emerged from the escape trunk.
Since the chamber at the scene was occupied, these individuals were transported by boat to the shore facility. About an hour and a half lapsed between surfacing and recompression, apparently because no chamber was available. Oficial de Mar 2o. Carlos Grande Rengifo developed such severe decompression sickness
(the "bends"), possibly combined with gas embolus
, that he died during recompression treatment.
The Peruvian Navy
's efforts to salvage Pacocha began on 30 August 1988, immediately after the crew escaped, and continued for eleven months. One hundred fifty men, seventy of them divers from the Salvage Service, worked eight hundred hours, two hundred of preliminary inspection and six hundred diving. The submarine broke the surface again on 23 July 1989, eleven months after she was sunk. After being studied for the effects of the ramming and sinking, her hulk was cannibalized for spare parts for other Peruvian submarines.
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
of the Marina de Guerra Peruana (Peruvian Navy
Peruvian Navy
The Peruvian Navy is the branch of the Peruvian Armed Forces tasked with surveillance, patrol and defense on lakes, rivers and the Pacific Ocean up to 200 nautical miles from the Peruvian littoral...
) named for the 1877 Battle of Pacocha
Battle of Pacocha
The naval Incident of Pacocha took place on 6 May 1877 when Nicolás de Piérola was leading a revolution to overthrow then Peruvian President Mariano Ignacio Prado. Piérola used the Peruvian monitor Huáscar as a raiding ship. She practiced sabotage primarily against the government forces of Peru...
, in which the Peruvian ironclad Huascar clashed with the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
. Formerly , a Balao-class submarine
Balao class submarine
The Balao class was a successful design of United States Navy submarine used during World War II, and with 122 units built, the largest class of submarines in the United States Navy. An improvement on the earlier Gato class, the boats had slight internal differences...
with a GUPPY IA upgrade, she had been sold to Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
and commissioned
Ship commissioning
Ship commissioning is the act or ceremony of placing a ship in active service, and may be regarded as a particular application of the general concepts and practices of project commissioning. The term is most commonly applied to the placing of a warship in active duty with its country's military...
on 28 May 1974.
At 18:50 in the evening of 26 August 1988, Pacocha was transiting on the surface with the forward torpedo room and bridge hatches as well as the main induction valve open. Forty-nine men were aboard, including the Squadron Commander, to conduct an operational readiness inspection. About half an hour after sunset, ten minutes from Pachocha’s expected arrival at the port of Callao
Callao
Callao is the largest and most important port in Peru. The city is coterminous with the Constitutional Province of Callao, the only province of the Callao Region. Callao is located west of Lima, the country's capital, and is part of the Lima Metropolitan Area, a large metropolis that holds almost...
, the 412 ton Japanese fishing trawler Kiowa Maru (also spelled Kyowa Maru and Hyowa Maru) rammed her in the aft port quarter. Kiowa Maru was equipped with an ice-breaker bow, with a sub-surface protrusion designed to penetrate and break apart what it struck. Pacocha sank quickly.
Four men died immediately in the collision and sinking: her commanding officer, Capitán de Fragata Daniel Nieva Rodríguez, died securing the bridge access hatch; Teniente Segundo Luis Roca Sara and two enlisted men were trapped in flooded compartments and drowned. Twenty-three of her crew succeeded in abandoning ship.
In the sinking submarine, Teniente Roger Cotrina Alvarado secured the watertight forward torpedo room door and attempted to pressurize the compartment. He then tried to secure the forward torpedo room hatch. Instead, however, he had to force the hatch open to free a sailor whose leg was caught in the hatch due to the 40 degree up angle the Pacocha assumed before sinking. As the Pacocha began to capsize water rushed into the compartment, washing lieutenant Cotrina down the ladder and fortunately, shortly afterwards, forcing the hatch door closed.
Cotrina credited this sequence of events to a miracle, testifying, “I saw a light and I experienced an ineffable power that allowed me to shut the hatch.” There is little doubt that if that hatch had not been shut, no one inside the submarine would have survived. Two commissions, one conducted by the Peruvian military, the other by the Vatican came to the conclusion that with the water pressure, it would have been technically impossible for anyone to close the hatch. As such the Roman Catholic Church
Roman Catholic Church
The Catholic Church, also known as the Roman Catholic Church, is the world's largest Christian church, with over a billion members. Led by the Pope, it defines its mission as spreading the gospel of Jesus Christ, administering the sacraments and exercising charity...
's Congregation for the Causes of the Saints authenticated the miracle. This is unusual, as normally miracles in the causes of saints, are those for cures believed by the Church to be through the saint's intercession, but in this case the declaration of a miracle was the obtaining of superhuman strength by someone in a disaster situation. On 6 June 2003, Pope John Paul II
Pope John Paul II
Blessed Pope John Paul II , born Karol Józef Wojtyła , reigned as Pope of the Catholic Church and Sovereign of Vatican City from 16 October 1978 until his death on 2 April 2005, at of age. His was the second-longest documented pontificate, which lasted ; only Pope Pius IX ...
celebrated Marija's beatification Mass ironically in the Croatian port city of Dubrovnik. Cotrina Alvarado received Holy Communion from the pope on this occasion, and afterwards gave him a small replica of the Pacocha as a memento.
Less than five minutes after the collision, Pachoca settled on the bottom at a depth of 140 feet (42.7 m) with a 9 degree up angle.
At 20:02, with Pachoca an hour overdue, the Peruvian Navy
Peruvian Navy
The Peruvian Navy is the branch of the Peruvian Armed Forces tasked with surveillance, patrol and defense on lakes, rivers and the Pacific Ocean up to 200 nautical miles from the Peruvian littoral...
declared an emergency. Boats were dispatched to search along Pacocha’s route. The tug Jennifer II was sent to rendezvous with Kiowa Maru and investigate. Some twenty minutes later, Contralmirante Guillermo Tirado, Commander of the Submarine Flotilla, arrived at the Callao Naval Base, assumed command, and dispatched the submarine BAP Dos de Mayo (SS-41) to search.
At 20:30, the survivors trapped in Pacocha released their messenger buoy and attempted to call aft compartments on the sound-powered telephone. There was no response.
By 21:00, the crew of Jennifer II had confirmed that Kiowa Maru had collided with something, and radioed their report to the base. While that report was in progress, the survivors in Pacocha fired a red distress flare. The Navy immediately issued a call for rescue and salvage divers to report for duty. Rescue of the survivors on the surface began at once, and within an hour and a half, twenty survivors and three bodies were drawn from the water. Three enlisted men had died of hypothermia
Hypothermia
Hypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as . Body temperature is usually maintained near a constant level of through biologic homeostasis or thermoregulation...
during the four hours they had spent in the 14 °C (57.2 °F) water.
Meanwhile, 22 survivors mustered in Pacocha’s forward torpedo room: four officers, four chiefs, and fourteen junior enlisted personnel. The senior officer transpired to be Cotrina. At 21:20 they fired another flare that led searchers to the messenger buoy at 21:31. Messenger buoys on Balao-class submarines
Balao class submarine
The Balao class was a successful design of United States Navy submarine used during World War II, and with 122 units built, the largest class of submarines in the United States Navy. An improvement on the earlier Gato class, the boats had slight internal differences...
do not have telephones, so communication could not be established, but those on the surface did realize that the buoy and flares probably meant that someone was still alive. The survivors held training in the use of the Steinke hood
Steinke hood
A Steinke hood, named for its inventor, Lieutenant Harris Steinke, is a device designed to aid escape from a sunken submarine,essentially an inflatable life jacket with a hood that completely encloses the wearer's head, trapping a bubble of breathing air...
, with which most crewmen were unfamiliar. (The Peruvian Navy
Peruvian Navy
The Peruvian Navy is the branch of the Peruvian Armed Forces tasked with surveillance, patrol and defense on lakes, rivers and the Pacific Ocean up to 200 nautical miles from the Peruvian littoral...
, like the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
, had stopped in-water escape training from depth several years previously.)
At 22:50, the smell of chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
gas in main control prompted another assessment of the boat's condition. A vent valve was found that had not been tightly shut, and more water had seeped into the aft battery compartment. All lithium hydroxide
Lithium hydroxide
Lithium hydroxide is an inorganic compound with the formula LiOH. It is a white hygroscopic crystalline material. It is soluble in water and slightly soluble in ethanol...
canisters were brought forward, and the survivors sealed themselves in the forward torpedo room. By 23:30, two canisters of lithium hydroxide
Lithium hydroxide
Lithium hydroxide is an inorganic compound with the formula LiOH. It is a white hygroscopic crystalline material. It is soluble in water and slightly soluble in ethanol...
were opened and spread. The crew was put to bed.
By midnight on Saturday, 27 August 1988, all twenty survivors and three bodies had been brought ashore. Survivors were taken to the nearby Naval Hospital. Although all suffered from hypothermia
Hypothermia
Hypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as . Body temperature is usually maintained near a constant level of through biologic homeostasis or thermoregulation...
, none had significant injuries. At the scene, an assortment of vessels were on the surface including the submarine, Dos de Mayo, a torpedo retriever, a floating crane, and several small craft.
Locating divers during their off-duty hours was hampered by the lack of telephones in many of their homes, but by midnight, eight were at the scene in SCUBA gear
Scuba set
A scuba set is an independent breathing set that provides a scuba diver with the breathing gas necessary to breathe underwater during scuba diving. It is much used for sport diving and some sorts of work diving....
. Depth to the deck of the ship was between 125 feet (38.1 m) aft and 110 feet (33.5 m) forward, with the ship variably reported as having between a nine and fifteen degree up-angle. The first team of divers followed the messenger buoy's line, which had played out to a significant distance. Since it was not located directly over Pacocha, a second line was tended straight down to the sail. The divers tapped on the hull and received a response from the forward compartment of the boat. However, they were unfamiliar with the code used, so were unable to interpret the tapping.
At 00:40, Contralmirante Tirado called Captain Schillingsburg, the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
Defense Attaché, to request rescue assistance from the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
.
By 01:00 the survivors had sent messages to the rescuers that they should be able to hold out for 48 hours. By 0200, three volunteers in Pacocha had donned oxygen breathing apparatuses
Oxygen Breathing Apparatus
An Oxygen Breathing Apparatus or OBA is a rebreather. It is used primarily in firefighting. Its oxygen is generated by chemicals contained in the green canister, which is inserted at the base of the breathing device....
(OBAs) and walked through compartments as far aft as main control. The aft battery compartment had water over the deck, so it was not entered. Meanwhile, personnel ashore including several divers studied the salvage air connections on BAP La Pedrera (SS-49) (the former , also a GUPPY IA Balao-class submarine
Balao class submarine
The Balao class was a successful design of United States Navy submarine used during World War II, and with 122 units built, the largest class of submarines in the United States Navy. An improvement on the earlier Gato class, the boats had slight internal differences...
) and discovered that they did not have appropriate salvage air hoses or fittings. Ultimately, Mark V diving system umbilicals were used with fittings manufactured during the night on two frigates. (Mark V diving hoses are negatively buoyant, ½-inch inner diameter, 600 psig (4.2 MPa) pressure rated hoses, MIL-H-2815.)
After two frustrating hours, improved communications with Pacocha were finally established at 02:27 using the signal ejector to pass written notes to the divers. Word was received at 0350 and passed to the survivors that the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
was sending its rescue system. However, over the next few hours the estimated time of arrival of the rescue system shifted steadily later.
Having had no communication from the surface for nearly two hours and unaware that there were currently no divers available, Pacocha fired another flare at 04:20. Yellow was picked so as not to give the impression that something new was seriously wrong—they only wanted to express concern that they had not heard anything in a couple of hours. However, at 04:40 a small electrical short and fire broke out in main control. It was brief and self-extinguishing, but renewed concern for the survivors' atmosphere. Only carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
extinguishers were available for fire-fighting.
A new group of divers arrived on scene at about 05:00 after reviewing salvage connections, escape trunk configuration, and other details on La Pedrera. Shortly after the divers went to work, they recovered the body of Pacocha’s Commanding Officer, Capitán de Fragata Nieva, just inside the deck access door to the sail.
At 06:00 the survivors held reveille and prepared breakfast. Utilizing the signal ejector, communication was passed that the crew was in good spirits with enough air to last for seventy-eight hours based on calculations of available oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
and lithium hydroxide
Lithium hydroxide
Lithium hydroxide is an inorganic compound with the formula LiOH. It is a white hygroscopic crystalline material. It is soluble in water and slightly soluble in ethanol...
. They also had adequate supplies of water, but no food after eating what little they had, including cake, for breakfast. While inspecting the submarine, the survivors noted a heavy black cloud rising from below the deck in the forward battery compartment. No one entered this compartment again. Two more canisters of lithium hydroxide
Lithium hydroxide
Lithium hydroxide is an inorganic compound with the formula LiOH. It is a white hygroscopic crystalline material. It is soluble in water and slightly soluble in ethanol...
were opened and spread on the upper bunks. Later in the morning another four canisters were opened. Approximately twenty canisters were unopened. One eight cubic foot (230 L) oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
cylinder was bled into the compartment; three oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
cylinders were left unused.
Information on the use of the escape trunk and the Steinke hood
Steinke hood
A Steinke hood, named for its inventor, Lieutenant Harris Steinke, is a device designed to aid escape from a sunken submarine,essentially an inflatable life jacket with a hood that completely encloses the wearer's head, trapping a bubble of breathing air...
was passed from the surface. The crew was divided into five groups and one member from each group trained in the operation of the escape trunk. Groups were arranged by seniority, with one officer in four of the five groups, and by other factors such as swimming ability and self-confidence. Via message, Pacocha informed those on the surface that there were twenty-two survivors.
At 07:30 a message was sent to Pacocha informing them that the fly-away rescue system was on the way from the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. This provided a visible boost to morale among the crewmen, and all involved in the casualty planned to wait for that equipment.
However, by 09:50, the crew was becoming listless, agitated, and hyperventilating. The boat's only atmosphere monitoring equipment was aft in the flooded compartments, but the lithium hydroxide
Lithium hydroxide
Lithium hydroxide is an inorganic compound with the formula LiOH. It is a white hygroscopic crystalline material. It is soluble in water and slightly soluble in ethanol...
did not seem to be working as well as expected. Cotrina was becoming concerned about the submarine's atmosphere. He spread four additional lithium hydroxide
Lithium hydroxide
Lithium hydroxide is an inorganic compound with the formula LiOH. It is a white hygroscopic crystalline material. It is soluble in water and slightly soluble in ethanol...
canisters. To exacerbate the situation, their only light, the emergency light located at the bottom of the forward ladder, was periodically flickering on and off, and the beam from their only battle lantern was steadily growing weaker. Cotrina passed a message to the surface requesting guidance. Contralmirante Tirado instructed Cotrina to use his best judgment in decided when to escape. Cotrina consulted his crew; their recommendations to escape were unanimous with one exception. Teniente Lindley offered various reasons to wait, and if he had to escape, he wanted the divers to provide SCUBA tanks
Scuba set
A scuba set is an independent breathing set that provides a scuba diver with the breathing gas necessary to breathe underwater during scuba diving. It is much used for sport diving and some sorts of work diving....
since he had been trained in their use. Cotrina ordered him to join the first group of escapees.
At 11:30, divers completed connecting high and low salvage using Mark V diving umbilicals for hoses and the manufactured fittings. The high salvage was connected to air banks on the submarine BAP Abtao (SS-42)
BAP Abtao (SS-42)
BAP Abtao was a of the Peruvian Navy.The submarine was built by the Electric Boat Company at Groton, Connecticut and delivered on 1 March 1954. She initially served as Tiburón , but was renamed Abtao in April 1957. Originally assigned pennant number 5, in 1959 she was designated SS-2, then...
, named after the Battle of Abtao
Battle of Abtao
The Naval Battle of Abtao took place on February 7, 1866, between a Spanish naval squadron and a combined Peruvian-Chilean fleet, at the island of Abtao in the Gulf of Ancud near Chiloé Archipelago in south-central Chile.-Background:...
. These banks were charged by thirty-five-year-old, oil-lubricated compressors. There are no filters on the system, and air samples of the air banks had never been taken.
During escape training, crew members decided to inflate their Steinke hood
Steinke hood
A Steinke hood, named for its inventor, Lieutenant Harris Steinke, is a device designed to aid escape from a sunken submarine,essentially an inflatable life jacket with a hood that completely encloses the wearer's head, trapping a bubble of breathing air...
s in the compartment before entering the escape trunk, and to use them as flotation devices, but not to enclose their heads in the hoods. One member of the first group, Chief Monzon, did wear the hood. He was to be the third most seriously injured of the twenty-two escapees. After inflating the escape devices, four men entered the escape trunk and controlled flooding and pressurizing from inside the trunk. After the side access hatch was opened, the four men spent at least ten minutes arguing over who would exit first. Finally Teniente Gomez, the senior man, ducked under and began his ascent, followed in turn by Chief Monzon and Petty Officer Reyes. All three men reached the surface and were promptly rescued. However, within minutes of reaching the surface, they began suffering great pain in their joints, became disoriented and unsteady, experienced shortness of breath, and displayed symptoms of crepitus
Crepitus
Crepitus is a medical term to describe the grating, crackling or popping sounds and sensations experienced under the skin and joints.-Causes:...
.
The rescuers on the surface had been told to expect four men in the first group. Finding only three, they began to search for the missing Teniente Lindley. While they searched, the survivors drained and opened the escape trunk, where they found the teniente, alive and well, still in the escape trunk. Lindley reentered the submarine, and was added to the last escape group.
The second group, led by Teniente Nieri, completed their escape by 12:25 without incident, and were flown by helicopter to the recompression chamber. The helicopter flew low over the water, to keep the air pressure as high as possible.
Immediately after the second group surfaced, air was supplied through the high salvage connection. When the connection was opened aboard Pacocha, high-pressure seawater came from the line since it had not yet been blown dry. The survivors immediately shut the high salvage connection valve and never reopened it. The low salvage line was open to atmosphere on the surface, not pressurized, but was connected to the submarine below the level of water in the bilge. Thus, that line was filled with seawater to a depth equivalent to the pressure in the boat, and did not allow air flow.
All five of the survivors in the third escape group completed an uneventful escape by 12:40. However, after they left, the outer escape hatch could not be shut from inside the submarine, so when the crew attempted to drain the trunk, seawater continued to flood into the submarine until the valves were secured. After the problem was communicated to the surface, divers investigated, discovered that the hatch’s dogs were obstructing closure, and freed the obstruction with a large wrench.
The fourth escape group made an uneventful escape by 15:15. On reaching the surface at least one of them was transported to the shore recompression facility by helicopter. The fifth group then made an uneventful escape by 16:25. By this time, a recompression chamber was on scene on the floating crane along with two medical officers. All three in this escape group were recompressed within five minutes of surfacing.
After the fifth group left the escape trunk, divers placed a set of SCUBA bottles
Scuba set
A scuba set is an independent breathing set that provides a scuba diver with the breathing gas necessary to breathe underwater during scuba diving. It is much used for sport diving and some sorts of work diving....
in the trunk. The final three escapees spent between one-half and one hour breathing from the SCUBA bottles
Scuba set
A scuba set is an independent breathing set that provides a scuba diver with the breathing gas necessary to breathe underwater during scuba diving. It is much used for sport diving and some sorts of work diving....
before escaping at 18:05, by which time personnel topside were again becoming apprehensive. Divers were sent to investigate the delay and were present when all three escapees simultaneously emerged from the escape trunk.
Since the chamber at the scene was occupied, these individuals were transported by boat to the shore facility. About an hour and a half lapsed between surfacing and recompression, apparently because no chamber was available. Oficial de Mar 2o. Carlos Grande Rengifo developed such severe decompression sickness
Decompression sickness
Decompression sickness describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurization...
(the "bends"), possibly combined with gas embolus
Embolism
In medicine, an embolism is the event of lodging of an embolus into a narrow capillary vessel of an arterial bed which causes a blockage in a distant part of the body.Embolization is...
, that he died during recompression treatment.
The Peruvian Navy
Peruvian Navy
The Peruvian Navy is the branch of the Peruvian Armed Forces tasked with surveillance, patrol and defense on lakes, rivers and the Pacific Ocean up to 200 nautical miles from the Peruvian littoral...
's efforts to salvage Pacocha began on 30 August 1988, immediately after the crew escaped, and continued for eleven months. One hundred fifty men, seventy of them divers from the Salvage Service, worked eight hundred hours, two hundred of preliminary inspection and six hundred diving. The submarine broke the surface again on 23 July 1989, eleven months after she was sunk. After being studied for the effects of the ramming and sinking, her hulk was cannibalized for spare parts for other Peruvian submarines.