Chasing lie U-Boats

Manawatu Times, Volume LIV, Issue 6625, 11 August 1931, Page 3

Chasing lie U-Boats

DETECTION BY SOUND. A glimpse of the working of the remarkably complete organisation for checking tho German U-boat menace during tho Great War was given by Lieutenant Commander R. P. Nisbct, D.S.C., R.N.R., in a lecture at Auckland entitled ‘ ‘ Chasing tho Hidden Enemy by Sound.” The high degree of accuracy attained in determining the position of U-boats by means of “fish” hydrophone, an instrument towed behind British naval vessels for picking up the sound of submarine, engines, was detailed by Lieutenant-Commander Nisbet. Ships of the trawler typo were specially built as hydrophone ships, and they worked in groups, or divisions, of three. Their function was to detect the prescnco of the submarine and signal its position to the destroyer, or similar fast vessel, that worked in conjunction with each hydrophone division. The destroyer’s task was then to steam quickly to the point indicated and drop a series of depth charges. “I was in command of tho Isth Divi sion,” said Lieutenant-Commander Nisbet, “and you will be interested to know that my ship was the trawler James Cosgrove, now so well known to Aucklanders. It is a coincidence that I should have followed her to New Zealand. It can be said that she has a history as exciting as that of almost any other trawler that saw war service. ’ ’ On one occasion his division detected a submarine about GO miles north of Iceland. For four days and nights they followed it, but owing to its superior speed it kept beyond their reach. Tho submarine commander knew, he was being followed, for submarines could always detect the presence of surface craft by tho noise of their propellers. He dodged and turned, and tho pursuing ship did the same, until finally they lost all sense of their position, being so engrossed in attending to their hydrophones. Early one morning during the chase tho submarine was sighted just as it was breaking tho surface, but it quickly dived. Depth charges were dropped, but without effect upon tho U-boat. The explosives, however, placed their hydrophones out of commission, and valuable time was lost in hauling them in and changing them. With new detectors fitted they picked up tho sound of the U-boat’s engines again, and the chase was resumed.

Then to the immense disappointment of all, when tho dawn of tho fifth day broke, they found themselves alongside the Faroe Islands, and saw tho submarine proceeding boldly on the surface, immune from their attack, since it was in Danish, and therefore neutral, waters. “To realise the significance of this,” said Lieutenant-Commander Nisbet, “you must remember that the submarine, like us, had been twisting end turning for four days and nights, here and there and all over the place. We, on tho surf ace,. wero lost. But he, under the surface, had managed to reach the islands. ; I must pay a tribute to his wonderful navigation. ” :