STOPPING UP THE U-BOAT HOLES

Dominion, Volume 11, Issue 201, 14 May 1918, Page 5

STOPPING UP THE U-BOAT HOLES

MB NEMINE AND MS CURTAIN A NEW IDEA Apropos of the recently cabled statement :by Mr. Archibald Kurd, the wellknown naval publicist, that the British/ .Admiralty had adopted a policy of lighting the U-boats by a eystem of blockading mine-fields spread over a vast area, the folloivia? article (by J[r. J. Bernard iWaikcr), in tho "Scientific American/' is of interest:—

It is pretty well understood (says Mr. Walker) that thero are two broad policies ty which the submarine can be fought. Either we may let the sub•nii'ino fleot pass out on to tho :ngu eajs, and then commonco a still hunt for its individual units, or no nay go to Hie source and shut up the U-boats •.within certain prescribed areas. Hitherto we luue been following tho furmur plan, and a rato of losses of 3,000,000 lo fli'O (KM' tons of shipping a yep.r, proves, ■a it proves anything, that the plan is a lihlum. JlJife fact cannot 1)0 questioni-J ; ftnd if iiiis murderous piracy is to be wiped out we must adopt the opposite and obvious policy of blocking the submarine bases shows that a more satist'acJuatins; them within their own waters. ihi3 ma} bb done in two ways. Vie icay institute a coast blockade by building cunt unions nets across tho entrances to Zeebrmjge Wilholmshaven, the Elbo, and t> l6 , Laltic, or wo raivy surrender tho •Hottn bca entirely to the German 6ur> eniL-mes and shut them within it by a ■"■all of obstruction across the English £oannel at Dover and across the N'orth ten from Scotland to Norway.

Closing the North Sea. /An ostimafo of the'total length of retting mid the total number of patrol o<^ts necessary iW closing these various *eb. manuo bnsos snovjs that n more s K-jJa... too- and more effective result un no obtalJ , by . , stalln * thß Smalts ■f ■ Dover nnd lnuWmg a huge not froin the coast of Scotland to the *?"?* 1.1. of r. Norw ar- ' It is stated that the Germans have equipped their with various tVpei of netcutting devices, which they claim are effective and will carry the larger subjnarines through any net that can be Jrailt. How trae this is we do not know. Rumour has it that faro kinds of cutters are used, namely, revolving knives carried well beyond the nose of'the submarine, and long keen knife blades extending from the bow aft, which, it is claimed, will cut through the heaviest wire work. This may be true, though uo doubt,it., Anyone who has tried to cut a piece of plough-steel wiro knows thai it requires a sharp chisel, an unyielding anvil, and no little muscular strength to do the .trick, and we very much doubt if any revolving knife or trazor-edge would cut through the thick but flexible wire of a heavy net.' A Curtain of Bomos. The most effective barrier would be a combination of the net and the mine, in which the net performs the function of a earner to sustain a continjoue wall of mines, so spaced that any submarine which touched the curtain would be , ibroached and opened to the sea in one or more places. Considered as a feat of engineering and seamanship, it would be perfectly feasible to build and maintain a bomb-curtain to a depth of 200 feet throughout the whole stretch of water ibetween Scotland and Norway—a distance of about 250 miles. Since fhe province of this net is to act merely as a carrier for a vertical minefield, it could i>e built of commercial one-half-inoh 6teel rod. The mesh would bo ten feet and the connection at the alternate intersections would consist of a buoyant spherical bomb, containing 20 pounds of trini-, irotoluol. The bomb 3 would bo built in Itwo hemispherical halves, with holes formed in the flanges for iho attach- ] mont of the lengths of wire re's. The I ends of the rods would be attached to the tomb by merely threading them through the flanged holes and twisting three or four turns of the rod snugly upon itself. Since the bombs would be spaced, 20 feet apart and etaggered, it is certain that at least one and probably three or four lxunbs would come in contact with a submarine that attempted to drive through. At the intersections, alternate with the bombs, connection would be made by a ring of tho same steel rod. ffhe bombs would have a sufficient positive buoyancy to carry their own load and a part of the load of the net itself, thereby making it possible to use floatation buoys of moderate size 20 feet be-1 low the surface. The net would be anchored by steel wire-rope extending from each side of the net and secured to heavy .mushroom anchors. Tho fact that soundings of the Norwegian coast show depths of from' 800 to 1000 feot, presents no £orious difficulty; it would simply ueceßsjiato the provisions of a greater length of mooring cable. Inevitably, the Germans, on finding themselves utterlv cut off from the Atlantic, would make desperate efforts to break through by sending a henvy force of ships to rush the net at luge speed, nnd carry it away. To prevent this, about a mile inside of the net there j ■would be strung across the North Sea from coast to coast and parallel with tho net, a continuous line of surface miues of the largest size, connected by cable and so adjusted that there would be two miles of this cable to a milo of linear distance, the cable being anchored at considerable intervals to keep it approximately in place. This would allow .sufficient slack in the cable to insure that any surface ship charging at it would carry the cable with it, and cause several of the bombs to swing into contact j against its side. .

Patrolling the Barrier. Inasmuch as the construction of a continuous wall of high explosives across the North Sea would mean the absolute defeat , at a single stroke of the whole German dream of winning the war by submarine piracy, we inay bo certain that desperation would drive them to employ every conceivable form of attack' against tho barrier. Therefore, to make assurance doubly eure, it would be well to establish, a mile or bo within the lastmentioned string of floating mines, ii thoroughly organised system of patrol by aeroplane, destroyer, and motor boat. The function of this patrol would bo not only to detect, and" as far as possible, provent tho approach of submarines to tho net, but also to maintain tho nod itself, malting good immediately any damage or displace, ment which it might sustain as a result of 'the enemy's attack, or the stresses of wind and weather. The bnsio element in this patrol would consist of half a. dozen mother ships moored in lino from coast to coast at intervals of from forty to fifty miles. These would form the supply depots from which the surfneo craft and aircraft would operate. The mother ships would consist of old tramp steamors (a suggestion of Mr. Charles G. Curtis), which would bo anchored securely by the head, heavy anchors and cables of great length being used, so that the fihips would tide easily in the heaviest weather. For protection againet torpedo attack each ship would be surrounded by a. double line of extra heavy torpedo netting, maintained in place by unusually heavy booms and guy ropes. At, the stern of each ship sections of the net would be arranged eo that they could be lowered- to admit the destroyers and motor boats when they came alongside for repairs and tho replenishment of fuel and supplies. In preparing these ships as starting and landing platforms for tho aeroplanes, they would be swept clear of all upper works, smoke-stacks, musts, rigging, etc., and landing platforms would bo built throughout their entire length, the platforms extending out twenty to thirty foet on. each 6ide 60 as to provide smooth runways, eay, 100 feet wido by Bomo 400 feet in length. _ The patrol would bo in three zones—the inner one extending between tho mother ships would be covered by tho flotillas of motor boats; the intermediate zone, from tfl-onty-fivo to thirty miles in width, would be covered by tho destroyers, and the outer zone, reaching one hundred mike or more into tho North Sea, would 1)9 under the watchful eyos at all times of tho aeroplanes. Bomb-Curtain versus Wire Netting. 'l.'hu advantages of such a bomb curtain over a. steel wire r.ct of sufficient strength in stou a SflOO-tou submarine, arejsn I

1. That because o? its simple construction and the speed >vith which the wire rods could bo turned out at the mills; it' could bo built in far less time.

2. That whatever the sizo and speed of tho submarine or the character of its net-cutting , devices, contact with tlio bomb curtain would mean certain destruction, or at least disablement. In this matter of defeating tho submariue, time is tho very essence of Ilia contract, and although" a curtain 200 feet deep and 550 miles in length is a colowal uiidort.ikinsf, it could ho built for a reasonable cost and within reasouablo time. The firing .mechanism of ,the bombs would have to lie of special design, to prevent the whole Jiet from being set off by sympathetic shock when one of the bombs was detonated. AVc underi stiuid that a firing mwlianism can bo produced, which will resist- the sudden shock from a nearby explosion, and can ! be operated only by a Wow or push of ! comparatively low velocity, such as would : bo applied if the firing pin were Struck by a submarine moving at a rale of eight or ten knots. To render tho bombs safe for handling by the-reamen as they build them into tlio net, the firing pin would be locked by a ceinont which would bo soluble in water, thereby insuring that tlio bombs would become alive only after they had been in water for ten or n.teon minutes. ' If the approaches to the North nca were protected by successive lines of aeroplanes, scouts, destroyers, and patrol boats, and finally by an impassable wall of bombs, it is snfe to say that the Atlantic routes would bo rid, once and for. all of the submarine pest, and America would be freo to sc-nd over food,.munitions, and troops without fear ot molestation. A similar net at Gibraltar and at the Straits of Oharito (the mouth of the Adriatic), would effectively block the submarine bases of Germany s allies.