These faced the multiple threats of acoustic mines and magnetic mines as well as attacks from the air and by surface vessels, especially after the fall of the Netherlands and Belgium.
22.
He then engaged in a series of recoveries between 12 June 1943 and 10 April 1944, during which time he defused four German ground mines, three magnetic mines and one acoustic mine.
23.
Similarly, the original broadband hydrophones of 1940s acoustic mines ( which operate on the integrated volume of all frequencies ) have been replaced by narrow-band sensors which are much more sensitive and selective.
24.
One of the earliest application of ADP crystals were hydrophones for acoustic mines; the crystals were specified for low frequency cutoff at 5 Hz, withstanding mechanical shock for deployment from aircraft from, and ability to survive neighbouring mine explosions.
25.
Arriving off Peleliu in the early morning of 12 September, while fire support ships opened bombardment, " Preble " separated to investigate the shoals between Anguar and Peleliu Islands where the enemy had been suspected of planting acoustic mines.
26.
But the two patrol vessels continued guarding the tugs and a special boarding team composed of Australian and American explosives experts searched the tugs and barge and found concealed within them a total of seventy contact and acoustic mines.
27.
Personnel from the 55th US Naval Construction Battalion and the RAAF Magnetic and Acoustic Mines Section were based at the depot, with the major camp area lying on the eastern point of the Forest near the present Hoop Pine picnic area.
28.
"' USS " Fortify " ( AM-446 / MSO-446 ) "'was an minesweeper acquired by the U . S . Navy for the task of removing Contact, Magnetic, and Acoustic mines that had been placed in the water to prevent the safe passage of ships.
29.
He studied physics at University College, London, and after a short period researching the viscosity of water under high pressure-- in his view " the dullest problem imaginable "-- he was drawn by World War II into military research, working on the design of magnetic and acoustic mines.
30.
On 23 December, " Wild Swan " was departing Liverpool in company with the destroyer when " Warwick " set off an acoustic mine, and was badly damaged, with the engine room flooded and the ship settling low in the water . " Wild Swan " towed " Warwick " back to Liverpool, allowing the damaged ship to be repaired.
