The eccentric engineer: diving to Pluto

Getting people and machinery to France was in some ways the easy bit of D-Day. Keeping them supplied when they got there was a lot harder. The War Office estimated that 60 per cent of all supplies by weight needed in France took the form of petrol and oil alone, so how were they going to get it there? The obvious solution was tankers, but there were concerns that deep-water facilities in Europe would be destroyed and shallow-draught ships might struggle in the choppy waters of the English Channel, especially under enemy fire.

Some fuel could be brought in jerrycans – 20 million of which were prepared for the journey – but what was needed was a backup and that took the form of one of the war’s most overlooked engineering marvels: Pluto – the PipeLine Under The Ocean.

Laying a pipeline across the Channel was no mean feat. Such distances had never been covered before and had never operated in such busy or rough tidal waters. Added to that, the enemy would be looking out for just such an operation, requiring the whole pipe to be laid in a single night. It was clear that some serious engineering would be needed.

Cometh the hour, cometh the man. In this case it was former WWI pilot and civil engineer Clifford Hartley who, as chief engineer of the Anglo-Iranian Oil Company, visited the Petroleum Warfare Department just as its team was deciding that Pluto was impossible.
Having laid high-pressure pipes across the mountains of Iran, he begged to differ.

The first problem was making the pipe itself. This needed to be incredibly strong, recoverable should it break, capable of being coiled in a cable-laying ship and camouflaged. Anglo-Iranian initially agreed to fund Hartley’s work with Siemens Brothers to produce the Hartley-Anglo-Iranian-Siemens pipe (HAIS). This 2in (5cm) pipe was made from extruded lead, cased in layers of asphalt, resin, steel tape and wire armour, and could deliver 3,500 imperial gallons (~16,000 litres) a day. After initial trials across the Bristol Channel, during which the line survived nearby Luftwaffe bombing and being dragged by an anchor, it proved successful enough for a 3in version to be commissioned. Eventually, 710 nautical miles (1315km) of pipeline were produced.

However, lead was in short supply so another design, Hamel, was also commissioned. This was lighter, being made from mild steel, but could not be wound on drums for cable-laying ships. Instead, the pipeline was turned around buoyant steel drums with conical ends, knowns as ‘conundrums,’ towed by tugs.

By early 1943, two pumping stations were being developed at Sandown on the Isle of Wight and at Dungeness, under top-secret conditions. So secret, in fact, that delivery drivers had to call from telephone boxes to receive final directions to the sites. These stations were to pump fuel through two pipelines named Bambi and Dumbo respectively.

For the initial invasion on 6 June 1944, much of the fuel was carried in shallow-draught tankers known as ‘chants’, but the unseasonably rough weather quickly put 16 of these out of service so Pluto was called into action. On 12 August, HMS Latimer laid an entire HAIS pipeline in just ten hours, only to lose it when its accompanying destroyer dragged its anchor over the pipe. A second effort ended similarly when the escort vessel somehow got the pipeline caught around its screw. Attention switched to the Hamel lines only for it be discovered that the conundrums left in Channel ports had become so encrusted with barnacles that they would no longer turn.

It was 22 September before the Navy had garnered sufficient expertise to successfully lay a HAIS pipeline for Bambi, followed shortly after by a Hamel laid with the newly careened ‘HMS Conundrum 2’. Then, less than two weeks later, both pipes failed, and the Bambi line to Cherbourg was abandoned.

Dumbo, however, proved far more successful. Running to Boulogne, 17 pipelines were successfully laid, with many surviving until the end of the war. As the Allies pressed on, and coastal oil facilities came under attack from German weapons, Dumbo was attached to an inland pipe system taking it all the way to Emmerich am Rhein.

Clifford Hartley meanwhile moved on to other engineering operations, creating the Fog Investigation and Dispersal Operation credited with safely bringing home over 10,000 aircrew and inventing the stabilised bomb sight used to sink the Tirpitz. For Pluto, the Royal Commission on Awards to Inventors gave him £9,000.