The wrecks of 16 British submarines lie in the English Channel. Of these, half were lost in accidents whilst in commission. M2, L24, A7, A1 and recently discovered B2 have become diving sites. Swordfish has been found and its location is a closely guarded secret. Of the rest, M1 and Affray were considered to be lying in water too deep to be visited by sport divers, even if the wrecks themselves could be found.
Innes McCartney's special enthusiasm for submarine wrecks led him to hunt for, locate and be the first to dive M1 and Affray. These landmarks in the exploration of British wrecks are related exclusively to 990.
One of the tremendously exciting aspects of Trimix diving is the potential to visit wrecks that have never been seen by divers before. This is made all the more exciting when the wrecks in question are landmarks in our maritime heritage. HMS Affray, the last British submarine lost at sea, and the supergun submarine M1 are two such examples. In 1998 the Starfish Enterprise (of which I am a proud member) were conducting work-up dives for the Britannic '98 expedition. This was the perfect opportunity to look for HMS Affray, which we were successful in finding that year. This year my attentions were concentrated on HMS M1.
We located the wreck in June, the culmination of much detailed research. That brings the stories of these two boats together is the fact that they shared similar fates. In some ways there is nothing more tragic than the loss of a naval vessel with all hands during peacetime. Both losses were front-page news at the time, in the case of HMS Affray, it relegated Suez to page two of the national newspapers. I am aware that the discovery of these vessels will be viewed with mixed emotions by some, they are after all the graves of 144 British submariners and should be accorded the respect they deserve.
HM Submarine M1 was developed toward the end of the First World War. Unique in the history of submarine design, she and her sisters M2 and M3 were fitted with 12inch guns from a scrapped battleship. This unique design was born out of the frustration of the submarine service with the relatively short range of torpedoes and their relative expense. These experimental designs were based on the hulls of the ill-starred K-class. M1 was completed before the war ended, but not employed in combat. One theory states that this was because the Royal Navy feared that Germany could copy the design. The U-boat war against British commerce might have taken a grave turn for the worse if such deadly weapons had been employed against Britain's merchant marine. It was, after all, Germany who had made the greatest capital out of the employment of the submarine as an offensive weapon of war.
After the war, the M-Class submarines were used experimentally in developing a range of new submarine technologies. M3 was converted into a minelayer and later scrapped in the 1930s. M2 became the world's first submarine aircraft carrier, carrying a miniature stainless steel-framed seaplane. M2 was also lost in tragic circumstances in January 1932.
M1's first commander was Max Horton, a successful wartime submarine commander who went on to become one of Britain's greatest war leaders when he was appointed Admiral, Western Approaches in 1942. Horton, the navy man who knew submarines intimately, became the killer of the German wolf packs. The M1's 12-inch gun gave her some unique sea-keeping qualities. The gun protected the watch in the conning tower from the worst the sea could throw at them by breaking the waves. Moreover the massive 100-ton weight of the gun turret gave it a fast diving time for such a leviathan. M1 could fully submerge in less than 90 seconds. Once submerged, the 12-inch gun (which was sealed at either end) became buoyant and also gave the vessel excellent handling qualities when underwater. However, when running on the surface, the gun made M1 top heavy and she was not the easiest vessel to control. The 12-inch gun was powerful enough to project the massive shells over 15 miles though a gunnery control system that would have permitted accurate firing was never properly developed. Instead, M1 was intended to be able to surprise its victims by firing at shorter ranges, with only its gun and spotting periscope showing above the surface. At a range of 1200 yards the gun had a totally flat trajectory and could literally be pointed at a target and fired. Not many vessels afloat in 1918 could be expected to withstand the devastating effect of such a bombardment. However, one of M1's drawbacks was that she was a 'one shot deal' because she had to surface to reload, making her instantly vulnerable to counter-attack. Therefore a close range attack, coming to firing depth and submerging was the best way she could be employed. With practice M1 got this routine down to less than 75 seconds.
It must be remembered that M1 was an experimental platform, not a mass-produced vessel. Because of this there were many teething problems with the design. These affected many areas and did cause the submarine a few embarrassing moments. If the hydraulic tampion gear which kept the barrel dry malfunctioned and the gun filled with water, when fired it would shatter.
On two occasions M1 lost half her barrel length when it simply went off in the same direction as the projectile. It is known that on another occasion when this occurred the steel winding within the barrel remained attached to the submarine and to the piece of the barrel that had broken off. The broken section landed in the sea a few hundred yards in front of M1 and effectively anchored her to the seabed. This is the only recorded time that a submarine has dropped anchor by firing her gun! In this case it was the seaman responsible for opening the tampion who had forgotten to do his job. He was most unpopular that evening because a shore leave could not be enjoyed since M1 was anchored out at sea!
A relatively high level of mechanical unreliability is thought to another compounding reason why M1 did not see action during the closing months of World War One. Some historians have suggested that plans had been made to operate M1 on a shore bombardment mission in the Bosphorous, fortunately these plans never came to fruition, possibly because of concerns over her reliability or potential for capture.
On 12 November 1925 M1 was on exercises off the Devon coast when disaster struck. She last dived at 07.37 and was not seen again for 74 years. Nothing was known about what had happened to M1 until 19 November when the collier Vidar entered Varta harbour and reported being in collision with an unknown object off Start Point at 07.45 on the 12th. Divers were sent down to examine her hull and they discovered that her bows were damaged. Traces of paint found on the Vidar seemed to be the same as the special paint used on M1 - a mystery had been solved. Although it was known roughly where M1 had been lost, she was lying in water too deep for safe diving operations and although she was located by the primitive sonar available at the time no attempt was made to inspect her. The M1 has been in the minds and ambitions of many sport divers over the years. This is because of the popularity of her sister, M2, as a diving site. Situated off Chesil Beach, near Weymouth, in 30m of water, M2 has been dived by countless thousands of wreck divers over the years. The story of the 'lost' sister M1 has always been a topic of conversation at these times. Until we returned with video footage which identified her she remained simply a footnote in history books and diver's logs.
The history of M1 is also now the history of those who sought to find her. Aside from the Royal Navy's searches in 1925/6, others have tried and failed to find M1. Claims have been made by commercial outfits and crayfish divers to have come across a 'giant submarine' while going about their work, but upon investigation these were found to be incorrect. This is partly because there are at least seven other submarines in the waters around Start Point. The most interesting of these claims came from a diving operator called Silas Oates. His M1 'find' made the national newspapers in 1967, as he claimed to be able to raise her. The Royal Navy impounded Mr Oates' boat shortly after the news broke. What made Mr Oates' story implausible was the comparatively shallow 150 feet of water he claimed she lay in.
To find the M1, I went back to basics and began with the information relating to the original Naval search for her. Although sonar was in its infancy, the information in the Public Records Office pointed to a number of interesting contacts found during 1925/6. However, the conclusion the Navy drew as to where the M1 was lying was clearly wrong. In fact I feel certain that this amounted to being a typographical error during the writing of the summary report into the findings of the search. I was also fortunate to be able to have access to the books of 'numbers' from Grahame Knott, the Weymouth charter boat captain.
Together we also managed to access some other positional information from trawlers and other dive charter operators. Within the search area we settled upon were three wrecks which we believed were undived and also of the right size to be M1. One site was firm favourite due to its location. On 18 June 1999 Grahame Knott took myself, Keith Morris, Chris Hutchison and support diver Patricia Hornabrook to the first position on our list. We had made hasty plans to go there because one of the invitees of my planned expedition to look for M1 (set for August) was attempting cut in front of me, get there first and claim the discovery for himself. What a brotherly lot technical divers have become! Upon arrival on site in beautiful, flat, sunny conditions, we were all excited at the prospect of being the first to discover M1. I entered the water and descendeing the shotline, video recording, out of the darkness in 73 metres came the unmistakable shape of an M-class submarine. The M1 had been found a last. For me, this was the greatest and most satisfying moment I have had in diving.
She is upright and leaning slightly over to port, relatively intact, the only obvious area of damage is the gun turret which is lying on the sand on the port side of the wreck. Her hatches are all closed with the exception of the forward torpedo-loading hatch which has popped open revealing a fan and some shelves neatly stacked with rows of china plates. The wreck is very heavily netted, with trawl nets wrapped closely around her. There are also several large monofilament nets in which the rows of dead fish become visible long before the netting. The fact that the gun turret has fallen off points to this being the point of collision with Vidar. Where the gun turret stood one can see the turntable upon which it sat with the rest of the conning tower silhouetted behind.
Subsequent to the dive we made on M1, I learned that HMS Bulldog, the Navy's survey vessel, had looked for her in 1991. The position given as being the most likely to be the wreck of M1 was in fact the position we dived - it goes to show that there is more than one way to skin a cat. Since being found M1 has been dived by several interested parties including a team from the BBC who are making a documentary about her.
As part of this program the marine accident investigation branch is investigating the sinking. I personally believe that Vidar was undoubtedly involved and that the gun turret was the area that was struck, flooding the boat. However the results of the official investigation into her loss will inevitably throw up more clues and produce much more solid evidence surrounding the sinking. We all await the findings with keen interest.
When she slipped from the docks of Cammell Laird, Birkenhead on 25 October 1945, HMS Affray (P421) was the embodiment of the latest submarine technology. The great submarine building programme of World War Two was coming to an end and HMS Affray was the culmination of several years of rapid submarine development. Her modular style of manufacture and all-welded hull were unique at the time. The A-class submarine was designed to operate mainly in the Far East. With this in mind she was fitted out with the highest degree of creature comfort for the crew ever seen on a British submarine. Affray boasted two air conditioning plants and refrigeration, all of her accommodation was fitted as far away from the engine room as possible. Most importantly, the A-class carried the biggest offensive punch ever fitted into a British submarine (with the arguable exception of M1) because she was fitted with a massive total of ten torpedo tubes.
HMS Affray was commissioned on 25 November 1945 and for five years was on travel and exercises all over the globe, visiting such exotic places as Durban, Cochin, Yokohama, Tangier, Singapore and Bergen. The last the world ever heard of her was on 16 April 1951, when she made a radio report while on exercise in the channel. After that, she simply disappeared. She was on a training cruise with a small party of commandos and 23 submarine officers under training, her entire complement totalled 75. When she failed to report on the morning of the 17th the largest ever search operation for a missing submarine was launched covering a huge area from Land's End to The Isle of Wight to the Channel Islands. A vast armada of vessels and aircraft were unable to find any trace of Affray. After three days of fruitless searching the hunt was scaled down because there was no longer the urgency to save life.
Affray had to be found however, her loss had caught the public imagination and wild speculation was rife as to what had happened to her. Rumours persisted that she had been captured by the Russians and many other equally implausible stories went about. Behind all of this, the Navy patiently searched for Affray. The search, which has become an epic tale in the annals of underwater salvage went on into the summer of 1951. Each time a new sonar contact was discovered, the naval salvage vessel Reclaim was anchored overhead and divers were sent down to investigate. This was a painstaking process, carried out in an area with literally hundreds of shipwrecks. Late in May Reclaim took possession of the first underwater television camera. Although initially sceptical of its utility, the crew quickly realised that it could vastly quicken the search process because it could be used for several hours either side of slack water.
On 14 June, two weeks after taking possession of the camera, Affray was located. She was south of the initial search area, on the north side of Hurd Deep in 278 feet. Investigations now followed to discover how she had sunk. Initial pictures of the wreck showed her to be intact, listing slightly to port, with her search radar and after periscope extended, as if she had been cruising at periscope depth at the time. It quickly became apparent that no attempt had been made to escape from the submarine and that her emergency buoy had not been deployed. This pointed to some sort of catastrophic failure which must have quickly overpowered the vessel and her complement. The only clue to show that some attempt had been made to save her was the sight of the bow hydroplanes being set to hard arise.
On the second examination of Affray, Reclaim noticed that the snort mast had snapped off. This 30-foot steel tube with a float valve on the top enabled Affray to run underwater on her diesel engines. The snort mast drew air down from the surface and returned exhaust gasses the same way. The snort mast was salvaged and sent away for investigation, where it was found to have broken off due to material weakness. Further investigations into the sinking continued for some weeks. Possible theories being investigated fell into two broad areas:
1) A battery explosion causing the boat to flood and snapping the snort mast due to shock (either from the explosion or from impact with the seabed)
2) Snort mast failure which caused the boat to sink directly.
As bad weather closed in, the examination of Affray was suspended without either case being truly proven. To this day no definitive answer has emerged. The diving conditions on the edge of Hurd Deep can be extremely challenging, it is an exposed area, taking in excess of four hours to reach from Weymouth. Tidal currents run strong and the visibility can be extremely poor. More importantly we were diving a very deep wreck and our long decompressions had to be carefully monitored. Fortunately we were operating from Skin Deep and were under the watchful eye of (the now sadly departed) Andy Smith, a skipper with much experience of diving in this area. Nevertheless, a dive such as this is not for the fainthearted. As it turned out the mark which was denoted as HMS Affray proved to be correct. On the Sunday of our first weekend of searching for her, we found HMS Affray.
As we descended down the shotline, a large dark shape emerged from the gloom. Little ambient light penetrates to 83 metres even on a good day on the edge of Hurd Deep and it was a while before we recognised the unmistakable shape of a submarine. She is a hugely impressive sight, sitting almost totally clear of a hard seabed, offering in excess of 10 metres of relief in places. Our lighting showed that she is now covered with sponges and anemones, offering some welcome colour in the darkness. The first thing that struck me about the wreck was her sheer size. She is one of the largest submarine wrecks in the Channel and a diver is hard pushed to swim all the way around her on a single dive. I was also amazed by her remarkable state of preservation. Her bridge is completely intact with speaking tubes, the projector binnacle and radio aerials all in evidence. On the side of the conning tower her navigation lights are present and the conning tower ladder is still in place. Her periscope shafts stand proudly upright and even the cables than ran between them are still there. Forward of the tower the foredeck is intact with the gun layers hatch clearly visible. I was keen to find the cradle in which the snort mast was located when in use. This was on the port side, aft of the tower and on our second dive on the wreck I found it. The base of the snort mast was still in place, with the area where the mast broke off clearly visible. On a later visit to the Royal Navy Submarine Museum, I saw the base of the section of the mast that was raised. They would still fit together perfectly. The fore and aft hydroplanes are still in position and the external torpedo tubes on the bow are a very impressive sight.
Our lengthy decompressions left the dive team with plenty of time for reflection about HMS Affray. As we quietly idled away in excess of 90 minutes of decompression stops we had time to think about her tragic loss and yet to take pride in the achievements of our submarine service. On the dives on HMS Affray, it was impossible not to be deeply moved by the quiet serenity of the wreck site. This is obviously in contrast to her last moments as she sank. Her loss was a terrible shock to the whole nation. To have seen her in her last resting place is an experience which left a profound mark upon all of the diving team. She lies, now, quietly at peace with the world.
The loss of HMS Affray is still a mystery. Considerable bodies of material relating to the investigations into her loss remain closed and outside the public domain. The material that has been made available to the public does little to add to the findings published in 1951.
Interestingly, I found some drawings in the Public Records Office which were done by HMS Reclaim. They show the snort mast leaning head down against the side of the submarine. We can deduce from this that the mast was still attached to Affray when she hit the seabed. In this case it appears unlikely that it broke off at the surface while in use because the mast would then be expected to be lost elsewhere, downstream of the wreck, on the bottom of the Channel. A more likely explanation is that it fell off as the submarine impacted with the bottom.
An explanation that I favour for the sinking is that the snort mast float valve jammed open, flooding the boat. A flow rate of around 13 tons per minute has been calculated for the volume of water which would have entered the submarine in this instance. This would have overwhelmed it very quickly and a manual shut off valve in the engine room needed to be closed in the case of such an accident. However, running with a reduced number of regular crew, it is possible that there simply wasn't time. It was not proven in 1951 whether this valve was open or closed as it was too difficult for the diver to access.
In stories of the location of new and historic wrecks the unsung heroes are often the captains of the charter boats used to take the intrepid explorers to their destinations. In case of Affray and M1, Grahame Knott in Wey Chieftain and the late (and greatly missed) Andy Smith in Skin Deep made these dives possible. Without them, it is unlikely that we could have made these discoveries. The Starfish group and myself have been longstanding customers of both captains. By building good relationships with them, we have been able to step 'out of the ordinary' type of diving and push the envelope a bit. Believe me, the fun begins when you really can 'boldly go where....'

By Innes McCartney. Full article appears in 990 Vol 2 No 1

Innes McCartney is intending to video all the known submarine wrecks in the Channel. He runs regular diving trips to submarine sites each year and is interested in hearing from any experienced trimix-level divers who may wish to join him on any of his expeditions. He can be contacted at, or via 990.