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Disaster Beneath the Waves

HMS Affray was the last RN submarine to be lost at sea. At the time of her sinking, rumours about the cause of her loss circulated widely. Many were discounted once her final resting place had been found and the Official Inquiry's report had been published. However, speculation persists to this day as to the reasons why she sank.

< p>HMS Affray was laid down at Cammell Laird Birkenhead yard on 16th January 1944 and launched on 12th April 1945. After being commissioned on 12th November, she was allocated to the 3rd Submarine Squadron, based on the submarine depot ship HMS Montclare at Rothesay, before joining Amphion Astute, Auriga and Aurochs with HMS Adamant in the British Pacific Fleet.


On 11th March 1949 she paid off to transfer to the 5th Submarine Squadron Reserve but stayed in operation at Portland until 2nd August to recommission for passage to Devonport. During refit there, all non-snort boats were retrofitted with a hinged air induction/exhaust emission snort mast which could be raised and lowered from the control room. Once vertical, it was self-locking and drew air into the boat at periscope depth to enable the diesels to be run for battery charging or propulsion. After this refit, she went to the South - West exercise ground before leaving for the Mediterranean in early November. It was recorded during deep dives Affray "leaked like a sieve" and that the Admiralty diesels "constantly gave us cause for concern, leaking oil and frequently falling down", presumably referring to the pistons.

In January 1951 Affray was transferred to a Reserve Group 'G' at Portsmouth but on 17th March she was brought out of Reserve and Lt John Blackburn DSC was appointed CO with the task of bringing Affray and the new ship's company up to operational status.


During docking in early April 1951, No 1 battery tank suffered a severe oil leak, repairs to which were anticipated to keep the boat in dock for some days. However, to everyone's astonishment visiting 'Brass' were overheard to insist that "This (A) boat sails on Monday". The 112 battery cells, each weighing 1/2 ton, were replaced without even ascertaining the cause of the oil leak and Affray undocked in the late afternoon on 10th April, then moved to HMS Dolphin for bunkering and storing.

In the early afternoon of Monday 16th April, Lt Blackburn mustered the Ships Company and told them Affray was to undertake Exercise Training Spring. This called for her to proceed west and spend several days on a simulated war patrol. At an unspecified time she would land and recover a small party of Royal Marine Commandos in two foldboats at night on any suitable Cornish beach. The exercise would continue until the morning of 23rd April, after which she would return to Portsmouth for docking and essential defect repairs, including the battery tank leak.

Her orders also included making a daily surface reports between 0900 and 1000 and to signal her position to Air Officer Commanding 19th Group RAF by 0900 daily. Some of the submarine crew was then detailed to collect their kit as they were to be landed for the duration of the exercise to provide additional space for the trainees. It is also recorded that another CO had refused to undertake this patrol, considering it too dangerous, with an ill prepared crew, to snort at night in busy shipping lanes.

After embarking a Marine Sergeant, 2 Marine Corporals, 7-Engineer Lts 13-Sub-Lts, Commander Engineer and Instructor Lt, HMS Affray slipped away from HMS Dolphin at 1615 on 16th April 1951. With 75 aboard, she was 30 miles south of the Isle of Wight at 2115 when her CO signalled his position at 50'10" north, 01'45" west and diving. On the morning of 17th April AOC 19TH Group RAF received no signal and submarine missing procedures were put in hand.

An hour later, no report had been received by the Admiralty so the Navy's submarine rescue procedures were implemented. Shore stations called Affray all day, whilst HMS Agincourt led a fleet of search vessels which eventually involved 24 from four nations. The Portland Second Training Flotilla, comprising of HMS Tintagel Castle, Flint Castle, Hedingham Castle and ASDIC trials vessel Helmsdale left Portland, as did the submarines Scorcher, Scythian, Sirdar and Auriga flying large white flags to distinguish them from their missing sister.

As Affray had been expected to surface some 20 miles SE of Start Point, the search was initially concentrated there. A number of faint hull tappings and distorted signals were picked up on hydrophones but the location of the sources, using cross bearings, proved fruitless. On 18th April, Ambush reported picking up code letter tappings representing "We are trapped on the bottom" but the source could not be traced. The following day, Scorcher was despatched to investigate a large oil slick near the Casquettes, 7 miles west of Alderney, but nothing was found. That evening, with little hope of saving life, the intensive search was called off. On 21st April, all A boats were confined to harbour pending investigation into the loss of Affray.


Following the loss of the Affray, the longest and largest search in naval history began. A flotilla of warships systematically searched the seabed over 1500 square miles. HMS Loch Insh was designated Leader and organised the search, in which sister ship Loch Alvie, ocean minesweepers HMS Mariner, HMS Marvel, HMS Pluto and HMS Wave, destroyer HMS Zambesi and survey ship HMS Cook were involved.

The submarine Sirdar sat on the bottom for over five hours south of Portland Bill to enable the searchers to identify a target in a similar situation. With hundreds of uncharted wrecks and divers able to go down only at slack water, progress was very slow until the Admiralty enlisted the aid of an underwater TV camera aboard HMS Reclaim.

Towards the middle of June, the search leader (an ex-submariner) shifted further south, calculating that Affray's CO might try to skirt the busy shopping lanes by taking the old wartime route closer to Alderney. Loch Insh herself picked up a contact and after making several cross runs over the target, those on board were convinced they had a submarine. HMS Reclaim was despatched to that position and lowered a camera 258ft, which picked out a brass handrail before scanning the bridge to reveal the name Affray.

HMS Affray had been found lying on an even keel near the edge of the Hurd Deep on a bearing 228 degrees and 67 miles from St Catherine's lighthouse on the Isle of Wight. She had travelled 37 miles SW of her reported position and was close to the area where the oil slick had been reported.

Divers could find no evidence of collision or damage to the hull, casing or bridge and it was noted that the search periscope and ANF radar mast were extended, indicating she was at periscope depth when she foundered. The hatches were all tight shut and the two emergency buoys were still located within the casing, although the after one could not have been released as the pair of hinged wooden gratings retaining it had been wired shut. It was realised that no attempt to escape had been made.

Subsequent dives revealed that the two sets of hydroplanes were at 'hard to rise' and the pointers on the bridge telegraphs showed both engines were at stop. But the most disturbing discovery was that the 28ft long galvanised snort induction mast had fractured about 3ft above the casing. Except for a sliver of metal retaining the two sections of the mast, the break was so clean that defective material was suspected.


On the 1st July the mast was lifted by HMS Reclaim for analysis and comparison by Admiralty scientists with two other masts from sister boats. No damage was found at the head of Affray's mast and the float valve was operating correctly, indicating it had not been struck by a passing surface ship. However it was found that the materials used were susceptible to brittle fracture and poor welding was evident.

Further research on rapid propagation of cracks suggested that, not only did a crack need a starting point, such has a faulty weld, but also an exciting force to set it off. Therefore, the mast should have stood up to normal operations, but might have fractured under a severe shock or an explosion. No external evidence of either of these forces was found, but could not be ruled out

The Admiralty was keen to see if the shut off valve at the bottom of the snort induction mast line had been operated. HMS Reclaim returned to the wreck with X-ray equipment and, after clearing part of the casing, radioactive isotopes were used to see through the hull. One isotope was accidentally dropped and the operation was abandoned in view of the radiation danger.

By then Affray had taken on a list to port. The cause of Affray's loss is officially attributed to the sheered snort mast, which allowed water to flood throughout the 10in aperture, due to failure to shut the induction valve within the pressure hull. Few submariners believe this, however as the operation is a routine one and could be undertaken by almost anyone on-board.

Beginning with HMS Andrew in 1949, the Navy started a programme to replace the masts on all A class submarines.

Several witnesses at the subsequent Board of Inquiry are convinced that their evidence had not been accurately recorded and some answers in the report seem not to relate to the questions asked. It is even alleged that the report has been doctored.

To understand the Admiralty's actions, one has to go back 50 years to a nation at war in Korea, a Cold War threat so great that war with the USSR was anticipated by Service Chiefs, and a population already shaken by the loss of life a year or so earlier when HM Submarine Truculent was run down in the Thames Estuary.


The Admiralty's priority was to convince it's own sailors that British submarines were safe, and also to convey to world leaders, and the general public, that RN submarines were highly effective weapons systems, tasked by efficient leaders and crewed by highly trained experts.

The RN played down their knowledge of Affray's known defects prior to sailing. Questions of negligence in sending the boat to sea were ignored, as were certain aspects of the first search and even recommendations of Court-martial. The Navy believed it best if the incident were forgotten.

What is clear is that Affray was not run down by a passing ship, nor involved in some cold war conspiracy, was not overloaded and not off course. The fractured snort mast must be considered a red herring, the break occurring as she hit the bottom with some force. It seems that Lt Blackburn, an experienced submarine officer who had had as his mentor the legendary Ben Bryant as CO in HMS Safari in the Mediterranean during the war, was diligently carrying out his orders as safely as the hazardous operation would allow.

With Affray tooling along at periscope depth, most likely snorting, some situation within the boat started a train of events which once rolling, no one was able to stop.


1 comment

Snort masts had a snort mast locking pin on the side of the fin some way above the casing, certainly higher than the 3ft height of the break off point. So this means that the locking pin wasn't engaged? This leads me to three scenarios....
1. They had forgotten to engage the locking pin after raising the snort mast.... but this was an important part of the 'commence snorting routine' and very unlikely.
2. They were about to start snorting and after the snort mast was raised but before the locking pin could be engaged something happened that led to the loss of AFFRAY.
3. They were stopping snorting and just as the locking pin was disengaged to allow the snort mast to be lowered something happened that led to the loss of the AFFRAY.
   Keith Hallam Fri, 23 Jun 2017

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RN Submarines scuttled or captured in WWII