It was a long time ago (1947). However, it stands out because of the large loss of life; most of the dead were employees of Harland & Wolff who were on board the vessel as it was undergoing sea trials after a refit.
The reason that the explosion was so devastating is because the crankcases of the four engines were linked together by sump ventilating pipes and vapour extraction pipes. Explosion doors as we understand them today were not fitted; Instead "explosion vents" were fitted at the forward and aft ends of the engines which consisted of a perforated plate covered by a bursting plate. The crankcases were not sub divided by baffle plates.
It is thought that when the engine was stopped because of an overheated piston in the port outer engine, oxygen continued to be drawn into the crankcase by the vapour extraction fan. The oxygen mixed with the oil which was vapourising on contact with the hot piston skirt and then circulated through to the crankcases of the other three engines.
When the port outer engine was restarted the crankcase explosion caused an increase in pressure in the engine room. This forced the crankcase doors of the other engines inwards bringing the revolving cranks of the engines into contact with the bottom of the doors. The flame from the explosion in the port outer engine entered the crankcases igniting the circulated condensed oil mist vapour blowing the doors outwards, and starting the fires in the engine room.
The lessons learnt from this tragedy are reflected in the modifications in design recommended to the inquiry:
(1) The introduction of baffles between each individual crank chamber.
Some of these recommendations which have been adopted and built into modern designs have led to the safer engines built today. The replacement of the old type of explosion discs with the modern explosion doors has also reduced (but not eliminated) the risk of the severe explosion.
If you are studying for a first or second class certificate of competency and wish to read about the development of the oil mist detector I highly recommend that you visit http://www.schaller.de Schaller manufacture the "Visatron" oil mist detector and this site describes the operation of this detector. Visit http://www.dieselsafety.org/index2.htm which Schaller Automation of Germany, the specialist for diesel engine monitoring and oil mist detection has initiated and is sponsoring. and read or join in the forum on crankcase explosions
See also http://www.kfp.co.uk/GravinerOilMistDetection.shtml for information on the Graviner oil mist detectors and http://www.oilmist.com the website of QMI who make a detector based on the light scatter principle.
I took the following report from http://www.argonet.co.uk/users/tjde.barry/PSNC/ which is a history of the Pacific steam navigation company by TJD "Barry" Erskine
This information has been reproduced with the permission of Steve Brew, http://brew.clients.ch/engine.htm
The following report of the incident was made by Harland & Wolff and is
an extract from their own files.
In 1947 the Pacific Steam Navigation Company's Belfast-built motor ship Reina del Pacifico was taken in hand at Queen's Island. When the refit had been carried out the liner crossed to the Clyde for speed trials which were completed satisfactorily on 11 September, though slight overheating was observed in one of the four twelve-cylinder, blast injection, trunk-piston diesel engines which had been installed when the vessel was built in 1931. During the return voyage to Belfast, while speed was being increased, all four engines exploded without warning. In an instant the engine room was a shambles, the lighting extinguished, ladders and access platforms destroyed and the atmosphere thick with smoke. When rescuers entered the engine room they found fires breaking out and bodies everywhere. The appalling result was that twenty-eight people died, either instantly or from their injuries, and a further twenty-three were hurt.
A public inquiry into the disaster concluded that overheating in one of the cylinders had ignited gases in the crankcase of one engine, causing an explosion which detonated her other engines. As the vessel was in the hands of the repairers, almost all those killed and injured were Queen's Island men. Among the dead was Leonard S. Brew, the Victoria Works manager in charge of the engines. He had been manager of the Londonderry repair works during the war.
The official inquiry into the accident, "Report of Court", No. 7951, adds the following details:
The formal investigation was held at the County Courthouse in Belfast 20-23 April, 26-30 April, 1 May, 3-8 May, and 10-13 May 1948, where barristers and lawyers represented the Ministry of Transport, the builders Harland & Wolff, and the owners Pacific Steam Navigation Company, and appeared on behalf of many, but not all, of the men killed, and their families.
The Reina del Pacifico, built and engined by Harland & Wolff in Belfast in 1931, had been owned by the Pacific Steam Navigation Company for 17 years at the time of the accident. Since her delivery, she had been employed as a passenger liner between the United Kingdom and the west coast of South America except for a period during the Second World War when she was requisitioned as a troop transport by the British Government. Classified 100A1, the ship was certified to carry 886 passengers and 301 crew, and was registered at the port of Liverpool.
After completion of her refit by Harland & Wolff following her war service, sea trials commenced on 2 September 1947, before her return to the owners. Almost immediately, the sea trials were cancelled "owing to serious overheating" of various pistons and cylinders. They were restarted 8 days later when Reina del Pacifico slipped her moorings in Belfast at 07:15 on 10 September.
Steaming through the Irish Sea and the Firth of Clyde, her engines ran constantly at various speeds for over 33 hours. As she was returning to Belfast, overheating in No.2 cylinder was observed, and her engines were brought to a full stop. But about 5 minutes later the engine was restarted.
Within a few short moments, estimated to be between immediately and 2-3 minutes, an explosion occurred, originating in the No.2 crank chamber of the port outer engine, followed by three further explosions in the crank cases of the port inner, starboard inner, and starboard outer engines.
In reply to question 25 of the inquiry, it was stated, "The primary explosion was caused by the overheating of No.2 piston of the port outer engine. The other three explosions were due to the inflammable content of the crankcases being ignited", which was explained as "a mixture of atomized [sic] or vapourised lubrica[t]ing oil, and air", which in turn began further fires within the engine room.
Using evidence at hand, it was estimated "that the piston of port outer No.2 engine had reached an average temperature of at least 500°F, with surface temperatures at certain areas of the piston well above 500°F, and in the vicinity of 1,500°F, as a maximum", although the spontaneous ignition temperature of the oil in use was approximately 720°F.
The accident occurred approximately 7 miles north east of Copeland Island in the North Channel of the Irish Sea at 16:46 on 11 September 1947.
The Belfast Weekly Telegraph reported a week after the accident, on 19 September 1947:
"Twenty-four people have died as a result of the explosion on board the crack liner Reina del Pacifico when on trials in the Irish Sea on Thursday of last week following the re-decoration at Harland & Wolff, Ltd. Some of the 22 people still detained in hospital have "improved", but most remain "critically ill".
"The great vessel was brought back to the Victoria Wharf on Friday. Dockers stood bareheaded as the ship was nosed up the river by tugs - a sombre contrast from the manner in which she had left earlier."
"MINISTRY ENQUIRY . . . Preliminary investigations have been made by . . . [the] . . .senior engineer of the Ministry of Transport."
"On Monday, 23 deaths had been reported, and then on Tuesday, Robert Thompson, an engineering draughtsman, . . . succumbed to his injuries in the Royal Victoria Hospital."
"Names of the dead are:- James Barnes, fitter ..., Leonard S. Brew, assistant manager ..., James S. Collins, fitter ..., Hugh Doherty, fitter ..., Robert Ellis, fitter ..., Harold Fay, assistant superintendent ..., F.D. Glenfield, draughtsman ..., William Mills, fitter ..., James McAllister, fitter ..., Edward McAllister, engineering draughtsman ..., John McBlain, fitter ..., R. McClure, fitter ..., Wesley Patterson, fitter ..., John Redmond, fitter ..., James B. Savage, fitter ..., Thomas Wilson, fitter ..., Patk. J. Dunn, draughtsman ..., Fred Johnston, first engineer ..., Robert Thompson, engineering draughtsman ..., H. C. Forbes, engineer ..., A. H. Jones, senior third engineer ..., J. Unsworth, engineer ..., R. McKibbon, assistant manager."
"The ship bears no outward appearance of the explosion, except that one of the funnels is black from the smoke following the blast."
"HEROIC SERVICE ... For three hours, Dr. Hamilton, in his first medical appointment, worked like a Trojan. He had himself lowered into the devastated engine room and with the assistance of the First Officer waded knee-deep in oil and other debris while striving to free those who were trapped. Then he organised a first aid service in the second class lounge, while stewards tore sheets and tablecloths into bandages. He is estimated to have bandaged nearly 60 men himself."
"RELATIVES' VIGIL . . . It was an anxious day for relatives of those on the ship last Friday. Many made a round of the hospitals and the city mortuary seeking friends. At one time five bodies were unidentified at the mortuary, but by Saturday afternoon all had been identified."
"From all parts of the United Kingdom letters of sympathy have [sic] been received. For several days the Union Jack at the City Hall was flown at half mast. Sympathy to the relatives of the bereaved was also expressed by the Prime Minister, Sir Basil Brooke ...."
The Belfast Weekly Telegraph, from 10 October 1947, reported:
"Inquest on Reina del Pacifico Victims"
"The accident that happened on the Reina del Pacifico seemed - and it is no exaggeration of language - just impossible, but it happened, said the Belfast Coroner (Dr. H. P. Lowe) after evidence of identification of 27 men killed in the liner explosion on September 11 was given at an inquest in City Hall, on Friday. The form of evidence varied little. Fathers identified sons and sons-in-law; brother came forward to testify to identification of brother. Only one woman relative appeared."
"THE WITNESSES .... Hugh Eardley ..., a chief officer on the liner, said he was on the bridge about 4-46 p.m. when he heard an explosion in the engine-room. He went there immediately and saw a number of employes [sic] lying in the engine-room and auxiliary room. Some of the men were severely injured and others appeared to be dead. He could not account for the explosion and was unaware of its cause."
"The explosion took place aproximately [sic] seven miles off the Copeland Islands."
"Alexander W. Barr ... said he was on his way to the main motor room and when near the main platform when he felt what appeared to be 'a hot blast'. On recovering his senses he found he was between No. 1 and 2 auxiliaries. He opened the door between the water room and the auxiliary water room and saw a man standing with his clothes on fire. He pulled him into the main auxiliary room and observed another man holding on to him. He repaired the lights and observed a number of men in an injured state lying in the main water room."
"Mr. Jefferson ... said the lost men were key men in the industry - skilled and trusted employes [sic] maintaining the reputation of the firm and continuing to enhance the glory and honour of the city. Their places would be difficult to fill."
The News Letter, on 11 September 1997, 50 years to the day after the explosion, recalled the incident, adding:
"In the 17 years since she had been launched, she had survived two fires, the loss of some of her most luxurious furnishings to German bombers and become infamous as the liner aboard which Ramsay MacDonald had died."
"Having served throughout the Second World War, the Reina del Pacifico returned to its birthplace within Belfast's famous Harland & Wolff yards to be transformed back to her former glory. She came through her main trials without incident, and then underwent special fuel testing."
"But as she returned to Belfast on the afternoon of Thursday, September 11, 1947, disaster struck just seven miles north of the Copeland Islands. As her speed was increased, all four engines exploded, ripping the heart out of the ship."
"Tugs and the Donaghadee lifeboat, carrying doctors and medical supplies, were rushed to the scene, while Royal and Mater hospitals were put on emergency alert to take survivors, the first of whom didn't arrive until shortly before 4am the following day."
"Dr. Ted Hamilton ... was the first medical man on the scene. Stripped to the waist, he was lowered into the darkness of the engine room where he waded through knee-deep oil to free the seriously injured trapped under twisted steel and debris."
"Responsibility for the incident was never fully established, with Harland & Wolff and the ship's owners, the Pacific Steam Navigation Company, sharing the compensation costs equally."
(Thanks again to Gail McMaster of Harland & Wolff for her kind help.