Bomb Disposal platoon

Korero (AEWS), Volume 2, Issue 11, 5 June 1944, Page 9

Bomb Disposal platoon

A KORERO Report

Bomb-disposal platoons work from three of the main centres in New Zealand — Auckland, Wellington, and Christchurch. They have never had to dispose of enemy bombs, since none has been dropped on this country, but they have work to do which is just as dangerous. They dispose of naval mines which are washed up on the coast or are sighted close inshore. Just in case you should be inclined to underestimate the risks in this work, consider this little story. Members of a bomb-disposal section were lying on the top of a 200-ft.-high cliff watching a mine drifting inshore. Part of the mooring cable was still attached to the mine, and apparently this caught in a reef. Anyway, whether that was the cause or not, the mine exploded. The men on top of the cliff were spattered with water and other debris, and the windows in a house three-quarters of a mile away were broken. Another story which the bomb-disposal people tell may be considered to prove that there are no risks in the work at allor you may think it proves rather that a certain Maori who lives in an isolated spot on the New Zealand coast is a very lucky fellow. A mine was reported at this remote coastal place. When the bomb-disposal

men arrived they found that the pakeha population consisted of the schoolteacher and his wife. So they asked the school-teacher where the mine was. “ Tied to a tree,” he replied. “ A Maori found it and tied it up.” And when the Maori was asked to elaborate on this, he related the facts, in strictly chronological order. “ I get the cream,” he said. “ I put it in the punt and I start to row across the bay. Then I see something bobbing up and down and I say : * That the mine.’ So I get the wire and tow him in and tie him up to the tree. And then,” he concluded, “ I run like hell ! ” It happened that the Maori had attached the wire to the only part of the mine it was possible to do so without exploding it ! The bomb-disposal men counter-mined this —that is, they blew it up with H.E. And when they turned over the mechanism plate which remained after the explosion, a huge crab, almost as big as a man’s hand, scuttled off from under itto safety. All the men in the bomb-disposal platoons are volunteers, and all except one N.C.O. in each platoon are nonmobilized personnel. The platoons are divided into sections and subsections, and one subsection in each district is detailed for duty each week. That means that one subsection is on call each week. If a mine is washed up in the Auckland platoon’s district this week, the men of the duty subsection are the men who will dispose of it. When the bombdisposal men are away on a job they are on Army pay, with no family allowances unless the job takes more than seven days. Some employers, of course, continue to pay their men while they are away, but there are some who don’t, and for their employees in the bomb-

disposal platoons this voluntary work may mean some financial sacrifice. When a mine is located on the coast it is reported to the nearest Army District H.Q., which calls out the local bombdisposal men. These men regard every mine as dangerous, even though they recognize its type and know exactly how to deal with it. They always have a minimum number —never more than two —within 500 yards of the mine, and they strip their clothes off so that there is nothing metallic about them. All doors and windows within a radius of three-quarters of a mile are opened to avoid damage by blast. Whenever possible mines are degaussed so that the domb-disposal men can see whether there is anything new in the mechanism. When this inspection is completed a signal is sent to a naval base for directions on the disposition of the mine. Should the mine be countermined or burned ? And does the Navy want the shell or mechanism plate returned ? When we say a mine is burned we mean that the 500 lb. of H.E. it contains is removed and burned in small pieces. The bomb-disposal men wear rubber gloves on this work to avoid the acute dermatitis which handling the H.E. would cause. Even though the H.E. is burned in small pieces the flame it gives is intensely hot and will fuse the sand for 50 yards round. 1 Counter-mining with an H.E. charge can be done only on a beach where there is no habitation within two miles. This is a method of disposition used when the mine is of a well-known type, and no more specimens of it are required. If the mine happens to be on an inhabited beach, and the bomb-disposal men want to counter-mine it they have to wait for the tide and then float it out to sea or remove it by other methods to some uninhabited place. Sometimes it is necessary to turn a mine over on the beach for examination. The procedure then is to pass a rope through two little holes in the mine, called “ lifting eyes,” and then, from a slit trench some distance away, to pull on the rope until the mine is in the desired position.

If you ask the bomb-disposal people to tell you exactly what a mine is they will probably reply, in Service style, that it is a non-mobile torpedo which may take any one of a number of different forms and which may be activated in any one of a number of different ways. The most common type is the anchored mine with all its variants, including several types of electric contact mine, antenna mines, mines which rise to effective position at a predetermined time after being laid, and mines attached to anchor nets. There are also floating mines, which may be dropped by a ship fleeing from an enemy, and, of course, the magnetic and acoustic types, which lie on the sea-floor. The experts will point out to you that all these differ from torpedoes not only because they are stationary, waiting for their prey to come to them, but because they are tactically effective in the absence of the craft that laid them. Each type of mine has its special uses and peculiar limitations. Anchored mines can usually be swept up by the simple expedient of catching and cutting the cables holding them to their anchors. Ships proceeding in unswept channels use paravane sweeps for protection.

These are simply underwater kites attached by cables to the stem of the ship. As the vessel moves forward they draw their connecting cables out sideways. These outspread cables form a sweep to catch the cables of anchored mines that would otherwise strike the vessel. The mine cables thus snared are drawn out to the paravane, where a cutting-device severs them. Since the cable of the anchored mine is of constant length, any movement of the mine away from a position directly over its anchor will tend to depress it below its effective position. For that reason this type cannot be used where there are strong currents or where the water is very deep, since the mine moves more freely with a long cable. A large fluctuation in tide-levels also reduces the mine’s potential effectiveness.

Magnetic and acoustic mines are generally made to lie on the sea-bottom, where they cannot easily be swept up. They must, however, be laid in water which is neither too shallow for shipping to pass nor too deep for the detonating mechanism to be activated. The first magnetic mines used in 1939 exploded from the sea-bottom, but later types incorporated a compressed-air chamber which caused the mine to rise closer to the ship’s hull before it exploded. Magnetic mines caused a good deal of destruction in the early part of the war, but they were quickly and effectively countered by the use of the degaussing belt,’’ which is simply a system of electric cables * girdling the vessel. The magnetic field set up by the current flowing f through these cables neutralizes the magnetic attraction of the | - ship’s steel hull. * ' . One advantage which mines t

have over torpedoes is that they can be laid, from aircraft, in areas which are not accessible to submarines. For instance, it was reported in the autumn of 1941 that planes based on Crete had dropped into the Suez Canal acoustic mines which sank three ships and forced the closing of the canal for eight days.

Because of the danger of a repetition of this, the canal was considered unreliable for military convoys coming up the Red Sea. Cargoes were landed at the south end of the canal and transferred by rail to Alexandria. By the summer and autumn of 1941 mines had ceased to take any substantial toll of shipping round the British Isles, but this state of affairs had been achieved only by a great effort. In September, 1941, Mr. Churchill said in the House of Commons :— “ We do not hear much about the mine menace now. Yet almost every night thirty or forty enemy aeroplanes are casting these destructive engines with all their ingenious variations at the most likely spots to catch our shipping. We do not hear much about all this now because twenty thousand men and one thousand ships toil ceaselessly with many strange varieties of apparatus to clear ports and channels of the deadly deposits of the night.”

Little is heard of those who toil to keep our- own coasts clear of mines. Perhaps some one some day will write their story, with a chapter about the men who wear the badge reproduced at the head of this article, the men who deal with mines which come ashore.