FINDING MINES

Wairarapa Times-Age, 2 December 1939, Page 7

FINDING MINES

! DIFFICULT AND DANGEROUS WORK. ACTIVITIES OF TRAWLERS. Somewhere quite close an enemy submarine is at work, writes the naval correspondent of the “Manchester Guardian." We have not seen him. He has been "detected." and as we do nol know quite what is his mission, there has been a hurry call for all arms. The submarine hunters are after him to keep him off the merchant shipping lanes. We are out to search for any i traces in the shape of mines that he may have left behind him. German submarine minelayers make occasional forays into our waters to lay j their cargo ol explosive in channel; that may be much used by the Navy and by merchant ships. It is the job of the minesweepers to see that those dangers arc removed. That may sound a simple sort of operation. Actually it is one of the most actively and continuously dangerous jobs that any naval men undertake, dangerous because the i most common way of finding an enemy minefield is to bump one of the mines and be blown up. Trawlers such as are used for this work are not built to stand that sort of shock. They have not, to put it mildly, an excess ol “floatability." In the sweeping service men will tell you rather grimly that the maximum time a trawler will float after she has struck a mine is 45 seconds. METHODS OF SWEEPING. If it were not for this subconscious knowledge of hidden danger one might think mine-sweeping a rather dull way of spending the day. It seems, superficially. to be just a matter of steaming along, five ships abreast, linked by wire ropes that are towed at different depths below the surface. But it may be that only one or two ships arc ' available, and they sweep with oropesas, a word whose derivation has beaten everyone I have asked so far. The ; oropesa is a steel fish which disports . itself dolphin-like along the surface carrying suspended below it a heavy kite and many fathoms of steel rope. It is towed by the sweeping ship, and i some law of dynamics that was not ) taught by my schoolmasters makes it i career away to a given distance from i the side of the towing vessel so that i from ship to fish there is stretched taut c under water a long sweeping wire, t This catches the mooring-rope of the i mine. 1 The towing strain tears rope and i mine away from the anchoring gear on the ocean bed. The released mine I float sto the surface, and then by gun f or rifle fire the sweepers crew either 1 blow it up or sink it by puncturing ' holes in the casing to let the sea 1 water destroy it buoyancy.