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A hydrophone attempts to listen to sound


is a receiving microphone in a

waterproof casing.When a noise occurs underwater – a sound wave – the vibration is

turned into an audible electrical sound.

The hydrophone research and training base was called HMS Tarlair (after the drifter in

which the first trials had been conducted,from Granton harbour) and was established at

Hawkcraig Point,Aberdour,in June


all,1,090 officers and 2,731 ratings were

trained at Hawkcraig,by parties visiting the naval bases,and by another school along

the Fife coast at Elie.

In charge of HMS Tarlair was Captain Cyril


assembled an unlikely team that

included top scientists,Nobel Prize winners,and a soprano singer.

The hydrophones were used in pairs so that a trained ear could locate where the enemy

submarine might be – low for port and high for starboard.The Navy thought the best people

to develop this would be the top musicians of the day.They recruited Hamilton Harty,who

was in charge of the Hallé Orchestra,and his wifeAgnes Nichols who was a famous singer.

The musicians sat amongst all the hydrophones and had to get them into piles,low for

port and high for starboard,and they used a hammer to tap the diaphragms as they got

them into


the middle of 1918,ten hydrophone listening stations had been set up

in Scotland,seven of them being in the Forth.They were mainly used to operate controlled

minefields,which could be activated electrically if a U-boat was detected.


Tearing the rules of war apart


nAugust 1914 Britain issued orders in council effectively closing off German overseas

trade.The blockade became progressively tighter over the next two years. On the 4th

of February 1915 Kaiser Wilhelm responded by signing an executive order that tore

the rules of war apart. It read “

From the Eighteenth

of February onwards all enemy merchant ships in the

waters surrounding Great Britain and Ireland will be

destroyed,irrespective of the impossibility of avoiding

in all cases danger to passengers and crew.”

Three months later,on 7th May,a German U-boat

torpedoed the Lusitania, a passenger ship sailing

south of Ireland. It was heading for Liverpool with

almost 2,000 passengers on board,many fromCanada

and the USA. The Germans had posted notices in

American newspapers warning of the dangers facing

any ships entering British waters but with a death toll of

1,189 there was international outrage against Germany.

128 of the victims were from neutral America,

and American outrage forced the Kaiser to end his

campaign of unrestricted U-boat warfare. For a while at least. Most significantly, the

sinking of the Lusitania had been a drastic demonstration of the potential of Germany’s

tiny U-boat fleet.


The laws of war, codified after

1856, set out to establish the rights

of neutrals and to protect private

property. Contraband was a legitimate

target, and was defined in two ways.

Munitions of war were absolute

contraband but other cargoes were

conditional contraband. Conditional

contraband was made up of goods

which could be intercepted if it was

destined for military use, but not

if it was not. It was the job of the

commander attacking a commercial

vessel to establish the nature of

the cargo before sinking the ship.

A submarine therefore had a duty

to surface, so exposing itself, in order

to put a boarding party on to the

merchant ship. If the cargo proved

to be contraband, the merchant ship

was given time to get civilians, crew

and any passengers off, so that when

it was sunk no lives would be lost. In

doing so the submarine exposed itself

to attack.

This was called prize rules, as

the ship’s cargo was a prize.

part 11 - below the waves

part 11 - below the waves

Lifeboats and drowning passengers

from a ship after being torpedoed by a

German submarine March 1915

The British had to quickly develop new techniques of anti-submarine warfare.

Cruising on the surface U-boats could be shelled or rammed. Hitting them under

water was more difficult. In 1916, the Royal Navy introduced depth charges. But the

question remained of how to detect submerged submarines in the first place. In search

of an answer the Admiralty established a research station at Aberdour on the Forth

in the summer of 1915 to develop what became a precursor to modern day sonar:

the hydrophone.