Forth during the winter of 1915.
A commercial vessel known as a “drifter” was commissioned HMS Tarlair and provided to then Commander Ryan for his experimental work in the fall of 1914. (Wilson, 1920)
The Admiralty’s first priority was to use the hydrophone as a defensive technology, and Ryan was their primary hope. Beginning in February, Ryan had tested his concept of mounting a hydrophone on a tripod set on the sea bottom, connected by cable to shore. By March the first hydrophone station was operating at Oxcars, a small island in the Forth, just south of Hawkcraig Point. This station was soon replaced by two other experimental shore-based stations in the Forth: one on the island of Inchcolm, the other at Elieness along the north shore near the entrance to the Forth.22
The Admiralty, of course, was delighted with Ryan’s rapid progress with this stationary submarine detection system, and the decision was made to expand his research, beyond what could be accomplished at Edinburgh’s Granton Pier. He must have been pleased when Hawkcraig Point was selected, as it provided access to an underwater environment much more appropriate for his submarine detection system development. Located along the northern coast of the Forth off the small fishing village of Aberdour, the water between Hawkcraig Point and Inchkeith Island allowed testing his ideas under conditions similar to where German ships and submarines might be operating.23 In modern terms, Ryan could perform the technical evaluation (TECHEVAL) and operational evaluation (OPEVAL) of any system he might devise, and Ryan’s creativity led to many such systems.
The Admiralty authorized the construction of a small building at Hawkcraig, known as “the Number One hut,” which was completed by the summer of 1915, and by the end of the year, the Hawkcraig Admiralty Experimental Station was born (see page 41). Lieutenant H. W. Wilson (RNVR), who served on Ryan’s staff throughout the war, recalled this new facility:
As a direct consequence of the erection of this hut, from this time afterwards, most experimental work was carried on from the north side of the Forth, and as the star of Hawkcraig waxed, so that of Granton, as a hydrophone base, waned … It was [in Number One hut] that the Captain’s marvels might be viewed, [which] drew hosts of distinguished visitors to our base, whether British or foreign, and it was certainly possible to detect a mystified awe on the countenance of the illustrious stranger, as he issued from Number One …24
CHAPTER 3 SIGHS OF A LOVESICK MERMAID
The first step necessary was a considerable increase in the instructional facilities for training listeners both for the increased number of shore stations and for the large number of vessels that were fitted for hydrophone work …
—Admiral John Rushworth Jellicoe, The Crisis of the Naval War, 19211
Britain’s First Sea Lord, Admiral John R. Jellicoe, was confident in the work being carried out at the Admiralty Experimental Station at Hawkcraig, but understood the need for the listeners to be properly trained. That would eventually happen, but from his now fully functioning and staffed station at Hawkcraig, Ryan continued with operational trials of his shore-based hydrophone listening stations throughout 1916, monitoring the sounds of passing vessels. The goal, however, was not just any vessel—rather a submerged, hostile submarine attempting to infiltrate a river, harbor, or when approaching any strategic waterfront infrastructure. The Admiralty, anxious to exploit the potential of this new technology, had been increasing the scope of Ryan’s work to include the use of hydrophones on surface ships.
The summer marked the growth of the shore hydrophone policy, and an ambitious and far-reaching programme commenced … So full of promise did the principal of the hydrophone appear to be in the detection of the submarine that, during the autumn and winter of 1916, a policy of offence was inaugurated.2
Listening stations served as an effective defensive measure, but throughout 1915, U-boats had turned to aggressive attacks on mercantile shipping. An equally aggressive antisubmarine policy became an Admiralty priority, and that priority was passed to Hawkcraig. Submarine hunting on the open seas required the ability to detect a U-boat as it transited toward the shipping lanes and certainly long before the predator could maneuver into a torpedo firing position. The vessels assigned to Ryan would now head beyond the Firth of Forth with this new mission.
British listener on board a trawler. He is rotating a directional hydrophone suspended from the end of the boom. (Courtesy Marist College; Lowell Thomas Archive)
Once again, Ryan began with a single, non-directional hydrophone. Although intended to provide mobility, the vessel, initially Tarlair, later joined by the drifter Couronne, had to stop while the hydrophone was lowered over the side. The vessel’s machinery would have masked any sounds coming from a distant target, and this early hydrophone was not designed to be towed far enough astern to eliminate the vessel’s own noise. The sophistication of these single hydrophone drifter systems would improve with time, but the practical-minded Ryan had an immediate need—detect the U-boat—and he would use what was available.
LISTENER TRAINING BECOMES A PRIORITY
But the concept of submarine detection depended on two things—the hydrophone and the listener’s ear. There were, however, uncertainties within the hydrophone service as to the quality of both. Lt. H. W. Wilson, RNVR, serving under Ryan, described, with a bit of naval irony, the medical exam given to those seeking membership in a service dependent on a sailor’s ears:
[I]t will not surprise you to hear that we were subjected to a rigorous medical examination on joining. All the organic equipment with which man is born into this world, including the vermiform appendix, was scrutinized and tested. Everything came under a punishing medical survey except only—the hearing!3
It would not be an easy job, that of the listener. The oceans resonated with the sounds of whales and other marine mammals, of the chatter from many species of fish and invertebrates, of storms that churn the ocean surface, and of waves crashing against the shore. But it was the ships, large and small, commercial and naval, that filled the depths of the oceans with sound. And then there was that new vessel—the submarine—whose characteristic sounds depended on whether it was patrolling on the surface with its diesel engines, or submerged and running on electric motors. Even the rotating propellers of ships and submarines created their own list of distinct rhythmic sounds. Ryan’s hydrophones were capable of “hearing” it all. It was a technology not well understood by those in the hydrophone service; yet with training, it became, according to Lt. Wilson, a trusted and valued tool:
All I can tell you is that a hydrophone is a piece of gear assuming various forms, containing a microphone,… [where] the flow of electrical current, results [in] the translation of the engine sounds of ships in the vicinity, and any other neighboring subaqueous tremors, such as the sighs of a lovesick mermaid. All this medley of sound is reproduced by telephone receivers connected by cable with the hydrophone, and the classification is left to the listener.4
Was it a submarine or a lovesick mermaid? With experience a listener could learn to distinguish many natural and man-made sounds. But it was the ability to classify specific sounds as being from a U-boat which would enable the hydrophone-equipped hunters to carry out an attack. Training was the key to success, and that became yet another mission for Ryan and his Hawkcraig staff. Candidates for the hydrophone service would learn to recognize the rhythmic sounds from a submarine’s rotating propellers and machinery.5 The “sighs of a lovesick mermaid”
