HMS Orpheus (S11): Setting a Free Ascent Record Off Malta

A Distinctive Aluminium Fin

HMS Orpheus was built by Vickers-Armstrongs, launched on 17 November 1959 and commissioned on 25 November 1960, an Oberon-class submarine that stood apart from her sisters in one notable respect: unlike the rest of the class, Orpheus's fin was made of aluminium alloy rather than steel.

She displaced 2,410 tons submerged, armed with eight torpedo tubes and fitted with Type 186 and 187 sonars, crewed by 68 officers and ratings.

The aluminium is more interesting than a curiosity. A submarine's casing and fin are the free-flooding structure outside the pressure hull, so they carry no load and hold back no water; their only jobs are to give the boat a shape and to carry the masts. Making them out of steel therefore means hauling several tons of metal around for no structural reason, and all of it sits high up, where weight does most harm to stability.

Aluminium answers that, and it has a second advantage: it is non-magnetic, which matters when the other side is hunting you with magnetic anomaly detectors slung under aircraft. Orpheus appears to have been the only Oberon built that way, which makes her the trial rather than the pattern.

The class settled somewhere else in the end. Later Oberons went to glass-reinforced plastic casings, which saved the same top weight, could not corrode against the steel hull they were bolted to, and had the useful additional property of not reflecting sound the way metal does. HMS Oberon sets out why that mattered so much. Orpheus was a step on the way to an answer somebody else got right.

A Record-Setting Escape Trial

Orpheus joined the 3rd Submarine Flotilla at Faslane in mid-1964, and in June 1965 took part in submarine escape trials off Malta, achieving a remarkable 500-foot free ascent record, a real test of both equipment and human endurance that pushed the boundaries of what submariners could survive escaping from a stricken boat at depth.

Five Hundred Feet, Over a Fortnight

The detail of those trials is worth having. This was not one heroic dive. A team from the Submarine Escape Training Tank at HMS Dolphin in Gosport spent about a fortnight in June 1965 in the water between Malta and Gozo, working progressively deeper, with Orpheus sitting on the bottom and men coming out of her a few at a time until they reached five hundred feet.

They used the forward single-man escape tower in her fore ends, which is a different thing from the five-man chamber some of the class later carried. A single-man tower takes one man at a time: he climbs in, the tower floods around him, the pressure equalises with the sea, the upper hatch opens and he goes. Then it drains and the next man climbs in. It is slower than a chamber and it is the arrangement most submarines actually had, which is why the record had to be set with one.

Malta was chosen for the obvious reasons: deep water close inshore, reliably calm and warm in June, and good visibility for the safety divers stationed up the ascent line. Doing this in the Clyde in February would have added hypothermia to a list of hazards that was long enough already.

And the point of it was never the record. Every man escaping from a real sinking submarine is relying on a number in a manual that says how deep it can be done, and the only way to establish that number honestly is for volunteers to go and find out. HMS Stratagem shows what happens when men have to use the training for real: ten got out of her in the Malacca Strait in 1944, and they were only able to because the water was shallow.

The phrase free ascent is the one to hold on to, because it describes something close to unnatural. There is no breathing apparatus. A man leaves the submarine at five hundred feet with a single lungful of air compressed to sixteen atmospheres, and as he rises that air expands, so he has to breathe OUT continuously for the whole ascent, all the way to the surface, or his lungs will burst. Every instinct a drowning man has is to hold his breath. The training exists to overrule it.

The same school went back and beat its own figure. In 1987, off Bergen, two instructors from that tank escaped from HMS Otus at 183 metres, six hundred feet, which stands as the world record to this day. Those later escapes were made in a hooded suit rather than as free ascents, so the two figures are not quite measuring the same thing, but the line runs straight from one to the other: twenty-two years apart, and both run by the same establishment at Gosport.

She also helped train Canadian and Australian crews destined for their own new Oberon-class submarines, part of the wider Commonwealth cooperation that saw the class exported successfully to several allied navies.

That training role has a nice symmetry to it. Australia and Canada each bought Oberons, and their crews had to be taught somewhere, so British boats spent years turning out foreign submariners to operate British submarines. Australia had been borrowing Royal Navy boats for exactly that purpose since 1949, which is the story HMS Trump tells, and buying her own was the end of that arrangement rather than the beginning of it.

A Collision and a Court Martial

On 15 February 1967, Orpheus collided with her sister submarine HMS Opportune near Portsmouth, a serious incident that resulted in Orpheus's commanding officer being court-martialed, a sobering reminder of just how unforgiving even routine harbour navigation could be. She went on to take part in the 1977 Silver Jubilee Fleet Review at Spithead.

The full account of that night belongs with the other boat, and HMS Opportune sets out what happened, what the damage actually was, and why an incident that sounds catastrophic produced a conviction for hazarding and a reprimand rather than the end of a career. It is worth reading for what it says about how the Royal Navy judges its commanding officers, which is that the standard is absolute and the consequences are beside the point.

A Long Retirement as a Training Boat

HMS Orpheus was decommissioned in 1987 and went on to serve as a training vessel at HMS Dolphin, before finally being broken up in April 1994, bringing to a close the career of a submarine whose free ascent record off Malta remains a properly impressive footnote in the history of submarine escape and survival training.

There is a neatness in where she finished. Orpheus paid off in 1987 and went to HMS Dolphin at Gosport as a training boat, which is the shore establishment that housed the escape tank whose team had used her to set the record twenty-two years earlier. She spent her last years alongside the institution she is remembered for helping.

She was broken up in April 1994, and Dolphin itself stopped being the home of the submarine service a few years later, the boats having long since moved to the Clyde. The escape tank outlasted both. Generations of submariners went up it before they were allowed to sea, knowing the depth figure printed in the drills was one that men had gone out and proved in the sea off Malta.