CHASING THE U-BOATS

Nelson Evening Mail, Volume LXIV, 6 August 1931, Page 4

CHASING THE U-BOATS

DETECTION BY SOUND EXCITING HUNT DESCRIBED FOUR DAYS AND FOUR NIGHTS A glimpse of the working of the remarkably complete organisation for checking the German U-boat menace during the Great War was 'given by Lieutenant-Commander R. P. Nisbet, D. 5.0., R.N.R., in a lecture entitled “Chasing the Hidden Enemy by Sound,” delivered under the auspices of tho Victoria League. The high .degrees of accuracy attained in determining the position of U-boats by means of the “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 tho trawler type wc.ro specially built as hydrophone ships, and they worked in groups, or divisions, of three. Their function was to detect the presence of the submarine and signal its position to the destroyer, or similar fast vessel, that worked in conjunction vvtili 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 the 15th Division,” 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 havo followed her to New Zealand. It can ho said that she has a history as exciting as that of almost any other trawler that saw war service.” Oil one occasion his division detected a submarine about 60 miles north of Iceland. For four days and nights they followed it, hut owing to its superior speed it kept beyond their reach. The submarine commander knew he was being followed, for submarines could always detect the presence of surface craft by the noise of their propellers, 110 dodged and turned, and, the pursuing ships did tho same, until finally they lost nil sense of their position, being so engrossed in attending to their hydrophones. Early one morning during the chase the submarine was sighted just as it was breaking the surface, hut it quickly dived. "Depth charges wero dropped, but without effect upon the 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, tbev found themselves alongside tho Faroe" Islands, and saw tho submarine proceeding boldly on the surface, immuno from their attack, since it was in Danish, and therefore neutral waters. “To realiso the significance of this,” said Lieut.-Commander Nisbetj “you must remember that the submarine, like us, had been twisting and turning for four days and nights, here and there and all over tho place. We, on the surface, were lost. But he, under the surface, had managed to reach tho islands. I must pay a tribute to his wonderful navigation.”