The fitting of these to the Type XXI U-boats operational in early 1945 introduced for the first time a submarine specifically intended to spend the majority of its sea-time submerged. Besides enabling a diesel-engined U-boat to remain continuously dived, by drawing air down the snort mast, the air quality within the boat was much improved, while her batteries could be kept charged. Engine exhaust gases are discharged through a separate mast, but ‘snorting’ carried risks beyond that of detection of the snort mast or her cloud of exhaust fumes. In heavy seas, the self-sealing head valve at the top of the snort mast functions less efficiently, allowing a considerable amount of water to come down the mast. While this is drained off into an internal tank, if this is not carefully monitored and regularly pumped out, it can result in a build-up of negative buoyancy which may only be evident when the boat slows down. Moreover, as the head valve shuts when the snort mast dips under waves, the running engines will suck air out of the pressure hull, thereby causing a vacuum in the submarine. This intermittent but cumulative situation, if prolonged, can cause serious loss of breathable oxygen unless the engines are promptly stopped. Alternatively, if the exhaust valves are shut with the engines still running, the boat can quickly fill with lethal carbon monoxide from the exhaust gases.
However, the biggest risk is failure of the snort system hull valve to shut when a submarine goes deep and shifts from diesel to electric power. If this occurs, severe flooding will follow. The loss of two French submarines, the Minerve in 1968 and the Eurydice in 1970, is thought to have been caused by this. Both sank in deep water in the Mediterranean and, as mentioned earlier, snort hull valve failure was considered a key factor in the foundering of HMS Affray in 1951. For these reasons drills and procedures associated with snorting were to feature as a very important part of the training class curriculum, a major feature of the prime element in the course: that of submarine safety. It was emphatically impressed upon the individual that error on the part of any member of the crew could very quickly imperil the boat.
Another key safety factor was that of battery ventilation. In the final stages of charging, hydrogen is emitted which, unless purged by the ventilation system, can quickly build up to dangerous explosive levels. Although modern British submarines have their batteries enclosed in separate compartments, unlike some other nations’ boats, this did not prevent explosions occurring. Battery ventilation failures caused two explosions, one aboard HMS Auriga in 1970, the second the following year in Alliance, in which in several men were injured and one was killed. Among the losses of nuclear submarines, of which there have been several, the most plausible theory for the loss of the American hunter-killer, USS Scorpion, in 1968, was that a battery explosion killed or disabled the control-room team resulting in control of the boat being lost and it sinking to crush depth.
At the closing phases of Conley’s own career in submarines, as the officer responsible for accepting new vessels from the shipbuilder, in 1992 he delayed the handover of HMS Ursula, the penultimate boat of the conventional Upholder class, until some damaged battery cells were replaced after a small explosion had occurred in her battery tank.
Should the worst occur, from whatever cause, it was essential that submarine crews should be able to escape from the confinement of their damaged boats. This could, of course, only occur if the submarine lay at a depth compatible with the ability of the human body to withstand the pressure, but if this was the case it was important that each individual had experience of such escape, for which nerve and a cool head were a prerequisite. The experiences of the late war combined with peacetime losses of submarines such as the Affray placed escape practice high on the trainees’ agenda.
Although by the 1960s all British submarines were being fitted with separate escape chambers, prior to that the basic method of escape was to assemble all hands in a single compartment. Each man wore an escape suit and all were mustered for what was called a ‘rush escape’, which took place through a canvas trunking rigged under the compartment escape hatch. This would be opened when the compartment pressure had been equalised with that of the sea outside by flooding the compartment. This rudimentary method requires each man to breathe pure air through a mouthpiece which is discarded on entry into the escape trunk. The safe ascent then relies upon the disciplined blowing out of air through pursed lips all the way up to the surface if burst lungs or a very dangerous air embolism in the bloodstream are to be avoided.
The more sophisticated chamber escape method had the advantage of each individual being evacuated in sequence, continuing to breathe freely all the way up to the surface inside a totally enclosed escape suit. This type of escape was periodically tested down to a depth of 600ft from ‘O’-class submarines sitting on the seabed, some of the crew volunteering to undertake the drill.
To familiarise trainees with the possibility of undertaking this hazardous procedure, training took place in the escape tank in Fort Blockhouse. This was 100ft deep and, in addition to having an escape chamber, had facilities at different depths which replicated the flooding of a whole compartment and the vertical escape to the surface following evacuation of the submarine. Such an evolution took place in benign conditions, in warm, well-lit water, with a number of instructors situated at various stages of the ascent to ensure the student was performing appropriately. Failure to blow out adequately in the training ascent was inevitably met by a firm prod in the stomach. All this would, of course, be a far cry from the darkness, the bitterly cold water and the fear prevalent in a real escape from a stricken submarine. Even so, it was not without inherent risk and in later years the value of pressurised escape training, with its occasional serious injuries or even fatalities, would be questioned. However, experience had indicated that it was highly likely that an untrained crew member would panic and fail to get out of the escape chamber, causing a fatal obstruction which prevented the remainder of the crew escaping.
Now aged twenty-one, Sub Lieutenant Conley completed the course in December 1967 and was appointed to the five-year-old ‘O’-class submarine Odin. The Odin belonged to the Third Submarine Squadron based at Faslane, on the Gareloch, Scotland. The boat had been intended to be based in Singapore but the Wilson government, intent on withdrawing from the Far East, changed all that. Instead, her ship’s company exchanged the intense tropical humidity which offsets the delights of Singapore, for the 65 inches of cold rain and the Scottish midge which assailed those who lived on the shores of the Gareloch. Despite being under training, he was Odin’s torpedo officer and was responsible for the casing — the external superstucture.