Saving Walcheren by Dudley Giles

PROF'ESSIONAL

PAPERS

OF'THE

CORPS OF ROYAL. E,NGINEERS, (FIFTH

SERIES).

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THE SAVII\C OF WALCHEREN BY BRIG. E. E. READ, C.B.E., M.C. Walcheren verdronk voor Europa's Bevrijding, October, 19tr4. (Walcheren u,as drowned

for

the Liberation of Ettrope)

Hrsronv

JN October, 1944, in order to make possible the capture of Walcheren and I t].r. opening 9.f the Scheldt to Antwerp, the R.A.F..bombed_the dykes of

the island. The operation was most accurately carried out, four openings were made, the sea poured in to flood tl.re island and the action of the tides soon served to complete the breaches and the general destruction. There were four gaps :-

Wesr l{eprlr-n. Nou-B (FrusrirNc). Vrnnr. Iler,rlrrrEus.

The Flushing-Veere canal with its high dyke banks served to divide the flooding into tr.vo portions. 'fhat to the north of the canal rvas entered by the first three gaps, and that to the south by the Rammekens gap. Generally the whole island r.vas polder land, i.e., land below high rvater and requiring artificial drainage. Unlike Holland proper * there were no other inteimediate dykes. There were very few pumps, but the canal acted as a bosom for receiving some of the normal water. There were pumps which evacuated into this canal, and sluices tvhich evacuated into the sea near Flushing during low tvater, closing during hish $'ater. The heights of flooding varied, but tvere in general round about I m. above N.A.P. (Nieuwe Amsterdam Peil : Dutch mean sea level datum.) As the tide range at springs was up to + 2.1 m. the sea rushed all over the island in every direction four times a day. Tl're '' refreshing " quality of the water-can be judged from the fact tl-rat all hedges, houses and ground rvere densely covered rvith mussels after a very ferv months. (Plioto b.)The canai lock gates rvere damaged, and up to July, lg4b, the daily tides rushed_through the canal. When the gates had been repaired the canal couicl be maintained at a level suitable for shipping, or lowered for drainage, or the gates could be ieft to swing open or shut freely accorditrg to tide level. .

* Holland " ptop"_. " is used in the Dutch

vinces

sense

of Holland to mean only the pro-

ol Northand South Holland. The restof theNetherlandsconsists of Frieslind,

Urrecht, etc.

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7HE SAVING OF \YALCHERE\ It

is often queried as to.why we could not restore the.isrand in the same way

it was orieinallv created,.

i1"qn.*r, rr"*ii.., thut th. i;i;e rr,"-. olgi.,.tty rvell above iieh water u"a onry'iiurali [y .t".*s. once it mJ u..r, oyt.a off and the m-arshes drained, plr". .;Jii;;;il;""iil'p..r.r,, much lorver levet. This process of drying o'er Holland and near Rofterdarn is as muih as an rnch or more a year. t N{ost of the island is surrounded by dunes. Th.;;;;. ,"i r.* i*perc.eptibte hillocks, Iike a bit of Midileburg and Li, ei.rii"i,'fo.-.a the islands of.refuge. Accommodation was Fanta.ti."iy " "? ..o*a.i'u?a i, *u. sight to see.a big Walcheren lace bonnet, foll6wed bv a l^::Tt":" .r."t race ano a pannrer skrrt emerging from the "ir"t German bunkers the dunes. _pigs, hens and ;1";.; ;h;rgh liss picturesquely *hi.h ,idal.d attired, were forced into theiame uncongenial q;r;;;. Transport everwvhere y4 ny. ,l'Dyk;i, or ,,Terrapin ,, and it took one keep, us and the'islana... going. The rvhole place was most ,"*":l?li' -r" rvith mines, a perpetual cuise lrberally sorvn ti the job. Ii.-s"t" *i.r.. rvould float away for any distance and quite a few reri.ained-r.iiri".'^Altnough every tree was_kilred, the land soured for a long time, and harf .r houses the Dermanently unfit, never have I heard a word .;_;i;;; against the heavv price that these gafr^a1t, .t"$"*l]"a".t.i""i "f l";il'd;; peopre ^'' have paii ?or the tiberatiof; oa E;r;;;."--^-' as

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THa BecrNNrNc

From october, 1944, oarvards, some Dutch Engineers (the bulk rvere then

in that part of the Netherlands still.occupied by G"r^irr*j/ r"gr" --'- ,t"ay o-'-- in. of the extent of the damage and the method of-thE repair. Liberation came in May, ro+s. By June it became apparent that the Dutch were not going to succeed in closing the gaps before ihe winter storms, and nornan,could.guess whether the islind worild still exist after that. rvere therefore ordered to sail in and do something ^"^tl",loyfl aDour rt. At llqil,.:^ hrst thrs appeared to be a most invidious task, to teach one,i grandmother to suck eggs-. - There were, however, several .o"tril"ttrv Lu,r.... -brrs_tly there was the terribre inertia, both personar and depaitmentar, l:lq persecution of the German occupa.tio" ;"J [t in" tong :i:,1* on ^ol a ^,\: pe'od dret bordering on.and even passin-g starvation limits, 'secondl! the,whole country had be-en absllutery ,iespoiGd of equipmenq-pt*i, r,unir tools,. and protective clothing. Fin-ally the problem was io vast and so new, and time rvas so short that blind reliance on traditional methods uto.r" .orrtd not succeed. something novel and original rnust be welded on to these sure methods ; great risks must be taken an-d a vast quantity of materiai must be poured in. _ Wrth{ a week, 700 tons of various materials rvere entering by L.C.M., L.C.T., Road, and Dukw. The vanguard of our effort.

TneotuoN

It may.be no.t inexpedient to review here the common traditional methods ev.olved through the centuries, and modernized as machinery rvas invented, The basis of these is the brushwood mattress : the suction dr'edger r and the

floating grab.

Mattresses.-These are in two forms :-those for sinking to provide the which heavy loads.of stone, or clay or even wrecks"are piaced ; and tnose useo to revet exDosed taces. bases on

jiri..lllrtll,iirr,l;rtii,.

Photo 3,-Flooded Island.

Photo 4.-Living in the garrets.

Photo 5.-The dry island. Average house damage. Note the sart water

mussers.

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Photo 6.-Floating Nlattress $'ork. First stase,

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Photo 7.-Mattress finished. Floated into position and about to be sunk *.ith stones.

Photo 8.-Mattress facinE rvork.

CROSS SECTIONS SHOWING METHOD OF DYKE CONSTRUCTION.

+ CLAY

2FIT

SLOPE I tN Z

H.\v.L? L.w L.) I I

SLOpE I tN 6 To I lN to AS WAVE ACTION DEMANOS

Plate g.-Dyke Construction.

THE SAVING OF WALCHEREN The construction of these is a most skilled job and entirely traditional to families living in the Biesbosch, the Maas-Rhine delta of marshes and islands and willows south of Dordrecht. In spite of centuries of use no other people can do this work and we had to import 400 skilled workers from thii area. I had formed the definite opinion lhat these processes are an integral part of an operation of dyke creation, that ordinary persons cannot do this work and that it would be advisable to import at least a nucleus of these skilled men.

This force was backed up by an immense family party in the Biesbosch; collecting the brushwood from the marshy islands. The fascines were usually made of willow, but any other local growths could be cut for the brushrvood filling and it is immaterial whether they are in leaf or not, though the material is easier.to transport without leaf. To this must be added tall rid stralv, hand bundled and not machine trussed. This came forward by L.C.T. and barge direct to site. process is interesting. Mattresses may be of any size, from 15 m. to - -The 100 m. square. They must be made on a tidal flat and are floated out, as they_cannot of course be lifted. It is here that the essential skill arises, and no slower work by unskilled labour achieves anything. It is like a trapeze act, where you either catch the bar or miss and'breali your neck. A rvhole mattress must be built in 3-6 hours between tides. (Photos 6 and T.) _-_Long fascines, the full length of the mattress are prepared beforehand. They are made in " horses," and are very compact,-although no chokers are used. Pegs are set out on the mud flat, at about 90 cm. centres, and the fascines laid in a chequer on these. .A rope is fastened at the foot ofthe peg gd led up through successive layers and used for the final tying. Brushwood about 10 cm. thick is then laid flat across the chequer: ihen reed

strarv: then brushwood : finally a repeat of the strons iascine chequer: and the rvhole bound up at each-chequir crossing by the"rope led through. Sbecial reinforcement is put in where low ropes aie ittached. Tlre quantity of rope used on this job was fantastic. In spite of great care in salvaging, we supplied.nearly a million foot run of S.W.R. and thi amount ol cordage was astronomical. The niattresses float at high tide and are manned by anythinq up to 20 men.

They are then towed to site, timed to arrive at slaik water, "and sunk. As slack water was only about 12 minutes either side of the iurn this was a

pretty snappy operation. Men are stationed all over the mattresses and stones passed by hand from flat-topped barges. Great care has to be used to do this evenly or the whole affair collapses. when the mattress is under r.vater the men, in lvaders, are rescued and big stones are thrown from the barges

floating over the top. Theie mattresses tend to become sodden and waterlogged after 4g hours, though exceptionally.they may last a week. Thus it was iirpossible to keep a reserve for emergencies, either of storm damage or of strikes. Face revetment is done in a similar way witfiout the bottom-chequer ; the pegs are left.in and steel cross_pegs driven through them to preventiifting. It is an education to see the skill with which billhooks are handled. (rhoio s.; Dyhe Building.-(Plate 9.) In still water or in tide rvater where there is still a gap to take the current, a clay wall is pushed out from the end of the dykeabout 2 m. above high rvater springs. Lirge suction dredgers brow sand in behind. If the water is very disturbed, a lar{e floating grabiwith a bucket frgr-n 2{ to 4 tons capacity, digs out a big ditch the full *iaih of the dyke base, rvhich may be up to 38 m. wide. The grab shuts itself in here so as tb remain afloat and working at low tide. Usually clay of a sort will be found up to I m.

THE SAVING OF WALCHEREN

belorv the surface which will do at this staee, The ditch is filled in sections by the sand blower. As this sand dries up, draglines are brought on to the new banks; they drag out sand to heighten the banks and the blower fills up the nerv ditch and so on. (Photo 13.) As the banks rise they are protected with clay up to 60 cm. thick or morc, immediately folldrved by matlress revctting, well pegged down. The rvhole is weighted dorvn by the biggest stones that can be packed on. In this case all stone came from Belgium, and barges were grounded at H.\V. Springs so that the lifting was downhill. A iittle lifting was done by R.B.s 15 and 19,

fitted as cranes rvith claws, but the output was minute. Normally up to 80 men rvould stand in a chain and pass stone by hand. Stone up to f ton

rvas levered downhill by hand.

Tsr

Pr-ex

'Ihere rvere three main partners in the rvork. (a) The Rijksuaterstaat, the State Dept. charged s'ith all the principal enginecr works

of-protection-main road-or

canal.

'l'hey appointed chief engineers, Nllessrs. \:erhev and Jansen, and they wefe responsible for the lvhole project: designed the lvork: laid it out : executed it. They commanded the huge labour force and organized the fleet of tugs, barges and cranes. (r) Delft Unixersity, who ran

a physical laboratorv under

Professor

Thysse. He

set up very large lvorking mcdels and on these rve studied the effect which closing one gap had upon the other gaps.

He recorded results of the day-to-day soundings at the gaps relative

to the tide levels, and observed the currents. He tested, and- showed to the actual tugmasters, the line of entry of the big difficult torvs, like the " Phoenixes," and decided on the times of closure. He worked out with spring balances the strains on all the anchorages as the closing ships rvere put in.

We decided the knotty point of r.vhen to close on a falling tide and lvhen on a rising tide, and rve thrashed out the controversial point of rvhether lve rvanted a narrow deep gap or a 'lvide shallow one Finally we r.vorked out the u'ave action of the sea on West I(apelle and found the right place to put the breakwater. Models rvere set up as large as 60 ft. across (you had to travel by overhead gantry). Vertical scale rvas 12 times the horizontal scale, and 6f hours of tide occurred in 3 mins. There rvas thus a slieht mathematical computation to transpose. Later each gap in turn was set up at this size. The late Lord Fisher stated. " there is onlv one useful tvoe of scale mcdel. That at 12 inches to the foot." fh. ru...s of our tests belies this and I think there *'ere no answers that we could not get, exceDt the effect of scour. We could not scale the srains of sand in two different dimensions. r:lus the fourth dimension of time. A department like this is essential in a rvork of such magnitude and pays an ample dividend. It must be stafied by absolutely first class people in whom the working engineers have complete confidence. One professor, one qualified assistant professor, trvo laboratory assistants and three workmen form an adequate full-time staff. (r) The Royal Engineers.-We provided many of the new ideas and tried to out them across. This was not alwavs easy as we had to learn the

i:,,;:ifjtrt

THE SAVING OF WALCHEREN background of tradition and then to persuade the Dutch ofthe soundof our ideas. These ideas of course grew gradually, and, as the Dutch gained confidence.in us, expanded and \vere put into effect or tested in the laboratory. The whole rvay through we were fighting against time, and for this reflson, every delay in testing a proposal lvai very qangerous. Our proposals roughly divided themselves into tlvo parts. Those we knew lvere sound, and those new or old techniques of which we had knorvledge and thought might be applied. Among the reasonable certainties I classed the following :(i) We could sink a ship of any size, at any place, in any given period of time, undamaged as regards resistance, and at the exict moment required. Here we never let them dorvn, much to their astonishment. A party of good Field Company Sappers, whose oficer rvas known to the Dutch, rvere the most suitable. (ii) A kite anchor will hold 26 tons or more and is unbeatable. It must be sailed in anything up to 300 feet. You cannot cast it anq exDect it to hold. -shuttle ness

boats are essential.

(iii) A D.8 tractor can beat all the tugs in the world and can pull 23 tons for certain. It is the only way of pulling a ship sidervays in a gap, and any rvinches that could be rigged are useless by comparison.

(iv) It is absolutely

necessary to have 100 per cent ternatives during a critical closing : (a) of ships to sink, (6) of men on the job,

(u)

reserve

or al-

(c) of filled sandbags, (d) of stone actually loaded on barges, (") of alternative explosive arrangements for sinking, (/) of tugs and vessels afloat, (g) of mattresses and hand tools. This lvas the hardest one to put across, as it was uneconomical, and it rvas often obvious that both of tlvo alternatives could not be used. There lvas however only one.criterion :-Would lve. or would we not, succeed in closing that gap ? If rve failed, literally millions would be thrown a.rviy, andlhis rvas insurance. For certain jobs, tractor equipment bulldozing for the dyke formation and scrapers for bringing up sand and clay rvere the proper

thing.

Draglines and decauville rvere outmoded. Of this I rvas quite convinced. When the first layer of the dykes had been built, and liquid sand shot in from the suction diedgers (20 per cent sand and 80 per cent water), it had been lifted up to form the sides by draglines. This was thought necessary as the site was in

such a mess, and was all liquid. - It was takine a week to drv out sufficiently to mot'e a criwler over it. We lot them to ticly up a bit and put a slope on the liquid sand of about l/40, dividecl

into several sections. It then dried so r.vell that we could put a D.7 or larger, with its good track-pressure distribution, to work in l_+ hours after the blorver had stopped. (Photo l7.) (vi) That Mulberry equipment in some form rvas necessary to close the gaps ; and that we could never get mattress, stone, mattress, stone, to stay put in the final stages of closing a gap.

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THE SAVING OF WALCHEREN

I t

Among the ideas for consideration which afterwards proved successfulwere:(i) The innumerable different uses for " Beetles "* (Photo 2l).

(ii)

i I I

I I I

(iii)

Torpedo ngtting thro-wn.in with clay to fill.an awkward gap. We used 1,200 tons of this during moments of great stress when closing gaps and it was the most iurprising rrr.i... The Dutch made a development of this and threw in two 70 cm. pipes, l0 m. long,.fastened by a to wedge in between two ships during -ch_ain, a critical moment of closing ; it was most successfut. lf froto ZO) The use of the D.8 with hyster as a mobile anchor, bdth movine and winching. It is interesting to, observe that the average tugl sea-going but not ocean-going, rvith a 1,b00 h.p. engine, witl ,r6t exert more thart about_5 tons push. Even bows-on to the long side of a 10,000 ton " Phoenix t' we could only get T tuss. rvhicf, produced an effort equal to one D.8. (Photo aZi)

(iv) Bailey equipment for

carrying_ suction dredgei delivery pipe,

60 cm. diameter and weighing about $ ton peimetre wtrentfutl, on to " islands " in the gaps. This rras neceisary when there rvere several branches in a gap_. Any attempt to push out the dyke from the fixed shore merely moved the " rivers ,' sideways, eroding ther'islands." These " islands " had to be made firm bv full dyke construction lvith revetted ends. (Photo 29.) A 500-ft. Bailey was set upr but never actually used as we had a lucky closure for one of the rivers. (v) What type of ship or Mulberry equipment to use for the.iob ? Here lve were all groping in the dark. The actual number of British personnel used was small, but the effort was very great. They consisted of :The Chief Ensineer Netherlands. One to two Pli. Mech. Eqpt. Dets. of a Fd. Coy. when-needed for sinkings. An anchoring officer (Watermanship). ,,Phoenix " sinking crelvs from Eneland. One Art. Wks. Coy. from time to iime for bridging, or preparing intermediates for demolition. A resident G.E. and Staff. A senior officer for liaison in The Hasue. A Stores Staff officer,,and part-time other S.O.s, R.E., getting stores, eqpt. and plant to the island. One Coy. Dutch Pnrs. under British Ccmd. Up-to one Bn. German Div. Engrs., taken off a standing mineclearance task.

One Coy. of Amphibians, R.A.S.C.

Help by Sub-Area for O.S. Stores for accommodation and protective clothinE.

Help by Civil Affairi Stafi.

':i

Visitors-A Standing patrol. The quantity of stores brought in was large, and their variety great ; . the result of very considerable research and planning by the Dutcl and

ourselves.

these three.partners rvorked as one. There rvas the greatest ^ .Th1g9gh9ut, friendship based on mutual regard, and the greatest frankness. It;as this frankness which ensured the success of the task, because matters were really fully discussed. There was only one object, Walclteren boven watei,

Walcheren above water.

See para, on Beetles under Nlaterials and Processes. (Page 9.)

THE SAV]NG OF WALCHEREN EqurrurNr, Nlerrnrers AND

PRocESSES

mav be of interest here to revierv the characteristics of certain items, in order to explain their use in the later notes of the adventures on the individual gaps.

Kipper Barges.-These are flat tofped barges on rvhich stone is loadedburden about 150 tons. They are towed over the site : a side valve is opened : the barge floods eccentrically and tips over 35 degrees : the stone shoots into the sea (on top of a sunken mattress) and the barge suddenly empties itself and riEhts itself. ItiJa blood-curdling sight and the operators have to cling on iikegrim death. They were ideal and we never had enough. Hopper Barges.-An ordinary hopper barge his sloping interior sides. if stone be loaded in these and the doors opened, a few stones drop out and the remainder form an arch and stay put. Special straight sided'hoppers had to be made. On opening the doors there is usually a small rattle, 30 seconds pause, and then the whole barge leaps about 5 feet vertically upwards.

Clay.-There is usually clay of a sort under the loam and sand. It

often mixed lvith peat, it comes out in small lumps, and tends to r.vash away in heavy currents. Good, heavy boulder clay is the ideal. The geologists found clay for us in the Hollandsch Diep, near Moerdijk Bridge, 120 km. sailing away. It paid to bring this up for all final gap closing, and one bucket dredger, 32 barges and 25 tugs were kept continually on this. Open barges were used as it rvas unloaded by grab. About 260,000 cu. yds. u.ere brought at nearlv l0s. a ton. Brusiuood.-About 3'8 million bundles were brought and L.C.T.s, and even L.C.M.s, trvere used to bring them to the inaccessible sites. Sand Barges.-These rvere of about 800 tons each and served the dredgers. Uo to 24 were used. -?zgs.-These were all steam tugs, 200-350 h.p. About 70 of these lvere in continual use. (Photo 32.) Up to 4 or even 6 of the largest ocean going tugs were continually used to bring _over Mulberry equipment from England. With storms and fogs we seldom caught up on our torving programme and never had enough reserves. Over 300 separate pontoons, from 5 tons up to 10,000 tons, came over.

Seamanship.-Throughout, the lvork was dependent on the seamanship of the Dutch tug-masters and of the watermen on the cables and winches of the various flotations. The quality r.vas above all praise and the job could never have been tackled with lonqshoremen, The orderly arrival of ton after ton of stone, clay, torpedo nets, g"rabs, etc., from -uny -i1". out to sea, often out of sight in the fog, had to be seen to be believed. It was all done by arrangement at the daily conference, there '"vas no lV/T and ferv signals. " Walkie-Talkie " was brought in for the " Phoenixes " and some of the bigger closing ships. Beach tilephones were good. Lig^hting.-\York usually went on night and

day. We provided

engines

and floodlights on tripods that could be moved around.

Stone.-This all had to come from Belsium and cost 30s. a ton at site. It was mostly limestone, S.G. 2.3, and in large

182,000 tons \,vere used.

blocks of

ton and small bits of

l-2

cwts.

__Th" stone for facing the dykes previously came from Bonn in Germany. This was unobtainabli and we hia to use the much lighter and inferior Belgian stone. This will never be a success on the facings, as it is too light and does not interlock. The result is that under heaw wave action it becomes a series of moving cannon balls, rvhich bombard the beach and dyke.

THE SAVING OF WALCHEREN The Bonn stone is unique in that it comes naturally in hexagonal prisms, which^p_ack a}tomatically alongside each other. It is basaltic, very^heavy, S.G. 3.f . The difference under water was even greater when thq relative weights of the two types of stone are in the propoition of 2.1 to 1.3. Had the heavier storle been available we could have reduced the stone imoorted by one-third

The Belgian stone came in open barges from Terneuzen, having come down from _Liege and many other places. The organization of this quarrying, partly by contract and partly by D.E.L.. of P.W. working in American quarries, was most complicated. Large numbers of British tippers had to be introduced, machinery lent and transportation arranged, all & them across a Dutch-British-Beleian-American-Civi Dutch-British-Belgian-American-Civil-P.W. net. This was unravelled by C.E., L. of C. We used up to 10,000 tons a week, and were always on the verge of a stone famine. Slach V[/ater.-The water never ran off the island as quickly as the sea fell, nor rose as_quickly as the sea rose, hence the currents it the-gaps, where the _water was always in a hurry to catch up with something. Siaik water on a falling tide was the best for sinking ships. Whether thJclosing should be done at slack water, falling tide, or slack water, rising tide, deplnds upon many factors such as :-

(a) (b)

(r) (d) (e)

(/)

From slack rising tide to high water, there is less difference in pressure than in the corresponding period at low tide. Ships will not ground if sunk on the rising tide and sinking depends on the weight poured into them. Ships may have diflficulty in manceuvring into position, on the rising tide. i.e.. between low water and slack. Whether holdfasts are available to let them in from either side and rvhat is the position as regards wrecks and obstacles on the inside and outside of the gaps. The time from slack water rising tide to high water is less than the time from slack water fallins tide to low water. The water pressure dependJ on the height of the sill.

When using slack water on a falling tide, previous to the moment of slack water, the sea level is above the island water, and though falling, is still rush-

ine in. Closing ships can be allowed to float in rvith the current, holding on their anchors. This starts about 20 mins. before slack with a current of uo to l0 knots. About 10 mins. before slack the current is down to 2 knots and the ship positioned. We then have l0 mins. to fire the charges and get away. This firing takes time as the firer has to climb out of the borvels of the ship, find his di-nghy, which has usually been taken fy d V.I.e. spectator, and row with some velocity. 5 mins. was allowed for this and 2 mins. for the ship to

''11",1**::":"lffll$ ll;]"ged,

and the ship preloaded, it hua rro* r to s metres to sink. As the water was falling the whole ship was soon exposed and its full weight came into play. There was then a concerted rush by every grab and barge that could get there, to filI up the ship and mahe it heavier still.

Ten mins. later the water was rushing out at 7 knots. This was the critical time as the differences in pressure grew and we had still not got full weight. As the tide fell there was a liability that grabs and barges themselves grounded outside. The previous filling of the gap had therefore to take this lnto account.

mf,kr|';;it,rnii)irrti,,;r;.;:;

THE SAVING OF WALCHEREN Neap tides were always preferable as the current was about half that at Springs. T_here was,also less chance of the servicing grabs grounding. We never actually- brought it off on exactly the best day, but planned forlwo to three days before.

The raage of Neaps was around

!'1.5 m.,with anything up to 2 m.,with wind. Slack water during ebb tide at Neaps rvas about 4 hours before low water. At L.W. the maximum difference in

more difference due to the

pressure occurred and all efforts had to be made to have the ship as heavv as possible by $is critical moment. If we succeeded in passing'this safely

rve had about 3 hours till slack water floods to make if safe -from water pressure on the outside, and a total of 6 hours before this outside Dressure reached its worst. The'r,vater level on the island had of course greater variations near the gaps. In the most favourable places inland the tidal range was as littre as 5 cm. during Neap tides and as much as 30 cm. during-Springs. The depthof flooding on a typical stretch, such as the Middleburg-Doribu.g road, varied between 30 cm. and 2 m. This meant that in a Du[lv yon ou"ie perpetuarly changing from swimming to wheeling. Beetles.-Beetles are the turtle-backed and turtle-bottomed pontoons used to carry the roadway from the Mulberry pier-head to the beaih. They are made in concrete and in steel. The concrete ones, with a displacement oi 160 tons, and ueight of40 tons, were the only really useful ones is we had to have lveight. All our operations qere coloured by the absolute necessity to get the maximum rveight in the first five hours. (Photo 10.) The top deck is I in. R.C. and must be opened up with a sledge hammer so that sand or clay can be dumped in. They do noi need explosive to sink ; a long steel bar can quickly punch holes through the bottom. ^The sides were impossible to crack with a sledge. (Photo 2l.l They are of use in a multitude of difierent rvays and .r,vere a Dermanenr standby. " Not,too little and not too big." They were plentiful, and reserves could be put inside a gap, but they then could not be ritrieved if the sinking rvas successful.

At first we tried "

Beetles

" side by side to make a complete gap closure.

This failed because .(a) orving to their shallowness we had to put immense quantities of stone on the sea bottom and bring the level up to a height where it r.vould barely hold.

(D) There were so many " Beetles_ " be put in at once to fill the gap that _to there was no time, as the final closure-had to be done simultaieouslv. (c) They all-had_to be sunk immediately as we could not get anchors orlt in the other direction in time befors the tide turned.

(4 fl"y were so light that we could not get up grabs and clay to fill them before they rvere swept away. (e) Although we let .them in rvith the ingoing water and falling tide, so that they would soon ground, we corrld not really start till 20"mins. before slack

water. Even then the current was about

most hardened tug men \vere frightened.

7$ knots and the

we fixed

a'n anchor boat do noithink sappers could have done any better. The first lot took_complete charge, swept through the gap . at 3 knots, and grounded I mile inland I Their principal uses were :-

and paid out from

this. I

(a) For closing a small gap quickly. Such gaps occurred when a ship fitted unevenly into a gap. (photo 21.)

THE SAVING OF WALCHEREN

For sinking-and getting sucked under a big ship on an uneven, or scoured-out bottom. (') For piling on top of a ship which had settled down too far due to the bottom scouring. (d) For sinkin! Iengthwise when pushing forward a dyke-head when we had almost reached the limit and it was washing away as fast as built. (') For sinking_crosswise to a dyke to act as a doorpost againstwhich to shut a big ship. (6)

Intermediate Pontoons,-:fhese are^Mulberry. concrete -caissons, absolutely rectangular, of varying sizes up to 800 tons dead weight and up to 2,000 tons displacement and up to 4'5 m. in height. This was the most useful and effective ship for gap closing. It r11s deep enough and heavy enough. we took all the concrete ones that could be found in the u.K., five in "all. We considered the steel ones too light. (Photos 14 and 15.) Before sinking all the hatches were removed. Fifteen 21ft. diameter holes were made in the bulkheads and the charges were fixed to cut out the bottom from four of the fifteen compartments ; reserve charges were placed in two more. This preparation took time and made the lorv somiwhat unseaworthy, though the hatches could be kept on. One intermediate pontoon hit a wreck just before coming into gap on a critical closing- (The crew of an L.C.T. had shot arvay the marking buoy by rifle practice the previous evening. There was some piain speakirig.) b"i compartment was holed, and as all the bulkheads rvere broken, she-sank. I found them in great distress, as a critical Neap tide rvas being lost and weather. deterioratinE.

The matter was easily_ solved by a few. handy sappers. All the fire engines the. island tvere p_ut into Dukrvs and swum up and brought along"side. They kept the water level down a bit inside whilst we put a pieci of rvool and a strut across the hole in the bulkhead. We then pumped out the rest of the ship and she floated with ample buoyancy and it was easy to patch and strut the hole in the bottom. This operation was completid in-12 hours. The charges, which were guncotton, were unharmed. Phoenix.-This is the largest Mulberry unit and is the concrete caisson used for breakwaters. It is 40 ft. high, 10,000 tons displacement and 2,500 tons weight. It was too big to manceuvre into place with comfort. Its main use was where the gap was so deep that nothing else would do. Rammekens was such a gap. Tugs bow on, pushed them in against the current, unlike all bther gaps. (Photo 32.) The Phoenix has no winches and no power. We felt they.were too big to pay out into place as they might take charge. In any case i if slightly misplaced they could never be unstuck against the curreni, and

readjusted.

We decided that the bottom, 2 ft. 6 in. thick, was too much to blor.v out without damaging the essential strength of the structure. A ring of beehives was tried on experimental concrete, but it was not certain thit the centre would drop out, and the back blast inside was not readily calculable. We therefore used the valves, with trained British crews. This gave a rate of about I ft. a minute or less, rather too slow as the current wis increasinE. It is not possible to preload if the valves were to be kept working, e"ceft with water or something porous. 800 tons of torpedo netting was put in fbr this purpose and remained porous. Two Admiralty floating pumps were used to increase the weight by putting in 600 tons of water an hour. As the Phoenix grounded and the tide fell.

i!'{!iii:,*it;,,;!Ltr,.,,t;,i,t,;,ir,i,i!r!:,1;,i.

.:: ..,.,;

Photo ro.-NoLLE. The Beetles,

Photo II.-WESTI{.IpELLE. Forming sand *'all rvithout bulldozers and shootins liquid betrveen. Note the dredger permanentll' built in.

sand

Photo

rz.-A

blower.

Photo I3.-RANTITEKENS. Blorving sand betu,een firm

cla1, rvall on the sea (left) side and sand rvall on the land (right) side.

,.-"---.-. .#.&

THE SAVING OF WALCHEREN

water had to be let out again. If the interior tvater is more than 12 ft. above the exterior she bursts open. The converse is of course not true as she is strutted by her bulkheadi. The 10,000 ton Phoenix with.its square ends is a formidable alTair when used for such an exact science as being placed to within a foot, and sunk in a defined period of 12 mins., all in a current of 7 knots. Like all the equipment used it was never designed for the purpose. At Westkapelle three Phoenixes were sunk as a breakrvater to protect the dyke ; the only case of the equipment being used for what it rvas intended. The positions were exactly determined by Delft University and it was a most striking succes-q. The cross currents were very bad ; with one ocean-going and six sea-going tugs we took two days to position the first Phoenix. Of.the_remaiqlng four Phoenixes, one was put into Rammekens gap and was literally swallowed up by the earth which opened to receive it. Another was used for the later successful closing of Rammekens and we were left with a reserve of two. (Photo 34.) Seven Phoenixes at {50,000 each equals {350,000. You could not tackle a project like this on the cheap ! , Syction Dredgers.-These are the traditional equipment which really produce the big results. The ones used had an output of up to 5,000 tons an-hour of sand and water mixture. They were all of original Dutch ownership, but many of them had been dispersed all over Europe by the Germans. There was much delay before these could be found and moved, especially due to . \ilater-ways being blocked by broken bridges, etc. One was found at Marseilles and broke adrift from its tue outside Gibraltar. One was salvased from the bottom of the Scheldt. Veiy few of these can both suck sand and push it. We only had one of this typi, and this was stationed at Westkapelle. Normally a sucking dredger is stationed as near in to the job as will enable it to float at all tides. As it is immobile, it cannot run away on the approach of heary r,l'eather. It must, therefore, be stationed in proiected watiis, and especially in waters without too much wave action as the rise and fall of the s]'ction pipe would prevent it picking up sand at the bottom and would break

tne

Plpes.

Rammekens three dredgers lvere stationed f mile out to sea. They supplied Rammekens, and also Nolle, about trvo hours steaming away. \reere was supplied by two dredgers floating about half an hour's steaming away. These " suck " dredgers discharged into sand barges alongside. Night and day a procession of barges is taken alvay full, and empty barges come alongside with great precision. The organization of this tug rvolk tvas a

masterpiece. The barges are brought alongside the blowers. There are anchored alongside the job as near in as they lvill float. This is often quite a yay off; at Rammekens up to 500 rn. A wooden pile trestle bridge ii then built to the shore to carry the discharge pipe, which-is branched to wherever the job has reached. The total length of discharge pipe may be up to 3 km. At Nolle the blower lay in shelter inside Flushing Harbour, served by the suckers down at Rammekens, and a 60 cm. pipe was laid right through the town. It could only serve the south side of the gap. There was no shelter on the north side, so no building-up could be dbne there. This fact had a considerable influence on the design of the closing, and the position of the place chosen for the last portion ofgap to be closed. At Westkapelle there was no shelter an)'where and the site was the most exposed on the whole.island. A combined " suck and push" dredger was brought right inside the gap in a " river " formed in Walclieren by the irosion. The sand and silt it sucked out was actually part of Walcheren and a larse

THE SAVING OF WALCHEREN

lake has now been left. she was left inside the final closure and will have to be dismantled or abandoned. At Veere two blor.vers were stationed, one on each side of the gap. (photo

21.) Work could thus go on simultaneously from trvo ends. it'had been intended to build aBailey to carry the pipe to the " island " in the middle of the gap, but a fortunate closure of the northern gap enabled the pipe to be carried on to the " island." such a bridge is a gieat nuisance is'there is continual ship traffic in and out of the gaps. At Rammekens two, later three, blowers were stationed. *.Fl2attn-g Grabs.-These^are powerful equipments of Dutch ownership. The buckets varied from.2| to 4$^tons capacily. They were most skilfully handled. Their flotation-_ls yp to 700 tons_ind they draw l'60 m. Anchoring requires to be verysoundly done. They also_have two_big vertical steel posts, steam driven, which they use as spuds to hold themselvei firmry fixed io the bottom. (Photo 30.) _ They are first used to excavate a ditch the full size of the eventual dyke. Later they are the principal equipment during the critical process of a closure. Barges with good.clay, with stone, and with torpedo netting, come in immediately the closing ship is sunk and their contents have to"be thrown into the casual openings that remain. often there will be water pouring under a ship and it is necessary to dump clay and stone over the ship, to 5'e sucked under by the current and_plug the hole. The biggest grab can only just plumb over an " intermediate," 17 m. wide. These widths are limiiine factors and have an important bearing on the sinking plan. CIay cannot bi dumped alongside the front face of the ship at first, and the grabs could not work for an hour each side of low water, even at Neaps. The shape of grab needed to lift clay was obviously not ideal for torpedo netting,-but, as time was very precious and both materials had to be dumped in, this had to be accepted. The netting just came up as a tangled bundle and sometimes even fell out and was wasted. Nevertheless. thev were handled with superb skill and I have seen netting actually sw.ng and ihrown by the grab beyond its travel into the hole needed. Theuse of thise srabs for stone was exceptional.

They had very powerful steam winches up to 10 tons. In severar cases they were anchored outside the jobs and the closing ships were paid out on these winches into final position. It was sometinies posiible to haui them off a 1ittle

to adjust position.

P.C, Pontoons.-These are rectangular steel tanks l.O7 m. square in section by 4.f2 m. long and about 12 tons displacement. They wire tried for a variety of purposes:-

They were rvelded up to form a gap closing ship. Twenty of them were welded up and put on to the deck of a phoenix to

it still hieher. They were pirt in groups of six, as a temporary measure, on to the deck of a sunken intermediate, over which high tide was washing, whilst sand was shot in behind. (Photo 18.) A lot of work was needed to,weld them together and large openings had to be cut, top and bottom, to allow them to 6e fitled up rvith ciay or"sand. make

Echo Sounding.-When large stones were dumped in gaps, it was often difficult to plumb accurately, as the plumbing poles mighig6 down between ty9 big stones. The currents were.very fierce and made hand plumbing difficult.- Any uneveness under a ship rnight burst open the gap after i closure. Very rapid and accurate profiles were needed the lasl few days

THE SAVING OF WALCHEREN before a closure, so we brought up echo sounding launches from a Survey ship. These can work in a depth of as little as 5 ft. and were invaluable. Kite Anchors.-These were a godsend and are one of the finest pieces of British equipment designed. The latest models have the stock u'elded up closed, so that it has some slighf buoyancy. This ensures that the flukes, being weightier, always drop first and the anchor is the right way uP. I consider that this anchor has a great future and may be used for many other R.E. war purposes, such as land holdfasts for suspension bridges. It must of course be sailed well into the ground by a ship or a tractor. It is not easy to recover, which is a nuisance for training purposes. Shuttle Boat.-This is a standard piece of Mulberry equipment and consists of two narrow floats joined by boarding. It can carry tv"'o kite anchors and 160 fthms. of cable on a drum. The cordage holding the anchor is cut and it drops, breaking the floor. It is expendabie and is a most useful adjunct for laying kite anchors in very shallorv waters. It makes placing anchors child's play.

Orurn Eeurpunxr N.L. Pontoons.-These are the same as those used for the " Rhino " ferry and other Tn. harbour iobs. Thev were useful but not essential. Scrapers.-TJp to 8 iu. yds. Not a great success except for trimming dykes. Principal use was for collecting sand on the side of a gap rvhere suction dredgers could not be placed. They rvere a failure on collecting clay. Draglines.-A great variety were used, from sizes R.B. l0 to R.B. 19. Lareer were unsuitable. The size R.B. 15 was, as usual, found to be the uniiersal happy medium. Back actors were not used, and forward actors very little, Bulldozers.-Larger sizes only used. Durnp er s, F lo o dli g ht s.-

Ample reserves re quired. Light Railuay-20 km. of main track, 90 cm. gauge, \&'as laid, plus 23 km. of small lines. A harbour was made by bucket dredger, 5 miles north of Veere, and a main line built to Westkapelle, so that if we had failed to close, stone and brushwood could be broueht all the winter to this exposed site.

L.C.T.s. L.C.M.s. Water JeePs. Sea Mules.-We hooed these r,l'ould be a success

with their square ends for pushing. Special i."*r w"t" trained carefully. They never iu-e up to expectation and were abandoned.

THe Geps The breaches in the dvkes varied from 400 m. to 900 m. Rivers had been formed in the island by the flow of the tide and emergecl sometimes in several definite differenf streams. Each was a potential gip. The scouring varied considerably and often altered whilst the closure r,vas in progress. The shallorvest main river was 4 m. belorv N.A.P. at Westkapelle. and the deepest 27 m. at Rammekens. In general the water came in through all the gaps, but tended to flow out mostly through Veere. Delft University examined critically whether any one gap, had to be closed before any other, and whether conditions improved or worsened as successive gaps were closed. They decided that there was an order of precedence, but that itwasnot so important as might be supposed. This rvas

THE SAVING OF WALCHEREN

most important conclusion as we co_urd not possibry have guessed the answer.

I}:Jol"*o

that currents definitely

*orr.'*a

u.'

.".r,

il;;;;;;;.p *".

We decided together that the order of priority rvas as follows :_ l. Iilestkap,elle.-Thi: was the most exposed site. It had to be done Derore tne worst of the autumn and winter storms, as to$.s could not be moved up there through. the rough seas. There was ro, tt. vessels on t]re job, and"in fact we never got"o.t.it., a la.ge gran ,rp "lgug.gq there at all. (photos 14,15. lT and lg.) 2. Nolle.-This'was the ,,exi *ori-"*p6."d site. vessers courd not rie here, but they could pop il and out of Fl,r.hlrrg, short notice.

(photos zz io bn.\ 3. Veere.-This was the widest. gap_, but it islands and not endangered 19 and 20.)

.was

ttre prevailing

" "rii. "*"y]at very sheltered by

the

S.\tr.;;;;.*lrnoto,

4' Rammehens.-This lvas,the

deepest and.most difficurt gap and exposed. There,was, horvever, som. shelter inria. if,"."aif,J fairry i,r"tq though tows could not be brought in during --it r, r.a -"grr *"^,lri'r.^"

a.separate, and proportion_ately, infinitery smal'ier flo"od area.

*u, ,ro,

was th"refore decided to sacrifice tni, g"p-?"i tti. 'ott.rr. (Photos 29, 8I,33 and 34.) .Work on all. these gaps went on simultaneously,_but Rammekens only got

vital. It

;lfitffi:fr

in equipment and never had its com"plement

"ir""ii""

j..ar;..

.As time went on, it became apparent that even this priority courd not be adhered to, as winter was upon-us.. There rvas also'the ,rlo.ilrioorau.rt question of_morale, which lvas steadily declining. It *ur ,r.""r.u.v'ii .rroou that we really close a gap, and it was dec"idea to o.r. ^could Decame readv flrst. "torl-iurri.ir..,r"., Nolle won, and was closed on 3 September, 1g45. Unfortunately, .breached it rvas by an exceptional storm on zo septemr.t, ud *i *"i"'rior." on than before, as the gap wur litt"reJ *iih il;i;. However we had shown that it could be done and ev"ryone p.ressed on with a stout t.u.t urra !r.;;;;;.^.y. The human factor of moraleis always present i; ;r;;y ;E;;,"".f. ee.ring, and nowhere could it have a.mori important b.;.i;dih;;.i.,"?i"gi"_ it all seemed_lost, and the.forces_ against which we were figitinj-*...'ro ".. ,rrrknown and immeasurable in their power. seldom ;l h;?.";ilr, *or. clear that the engineer who approaches his probrem """ i" i..ri.?a.rign, of.maQhines, and of materiat is'only to u r*uil degree ""ry master of his profession. The Dutch were fortunate in theii re,aders, and i'n the ;ai; p.y;h;i;iis"ts rike Den Doolaard, lvho came to this task.

Tsn ClosrNc on a Gap The details of the processes have been set out in the various precedine paras. In every case a line was chosen by the.Dutch,.for the,,.,u dyk.,.u.fi inside the breach. Three factors weighei in this chorce :_ (") Protection.

(b) Getting a small harbour. (') The,dJpths of the_gap and of the " rivers rvould be made. (Photos 2g and 31.)

where the eventual crosure

has become clear afterwards that there is no need to be frightened of

Iittle extra length. Dyke building is quite quick. It ir ih.-fi;;i'*.o1r,., a tricky. We wire all rather in the"dark as to how thi, fi;;i;;;*?l.iij*ort i, out, and learnt as we went. At first traditional methods *.t'"'ur.J ro, a"t.

Photo I4.-WESTKArELLE. Trvo Intermediates being to*'ed into position from the land side torvards the sea against a slight ingoing current. This had to be done as too rougb to strtiolr grabs, and tugs could not be permanently built in, inside the gap.

:::L

r f,',;

Photo r5.-One hour after the above.

Photo I6'-RaMMEKENs. Pushing for*'ard heavy clav. Mattress revetment at the end.

Photo r7'-wESTKA'ELLE' All tle stages of facing,. sand, clay, mattresses, . stones. Note closing Intermediate armost buried and b;;l;?.i"s of urtifi"iui il;;ri 6"i;g built up. the

THE SAVING OF WALCHEREN building. Any " rivers " on the way were blocked as there was a safety valve in the main outlet. It is not possible to " boom out " the end of the dyke into the river because the channel then merely moves sideways. The dyke is built through the flood-rvater to the edge of the river channel, and simultaneously from thti*" island " opposite. Mattresses have, meanwhile, been sunk in the channel and stone dumped on them to hold them down. Sand is shot in from the suction-dredger to build up the hole in the river and prevent mattresses remaining a knife-edge. A suction dredger can shoot 6,000 tons an hour, of rvhich 1,000 tons may be sand-sometimes one is lucky and 100 tons of this stays and is not rvashed away. Clay is then dumped on the stone on top of the mattresses until the new- dyke begins to show above low water. From this stage onwards it may be necessary to use stone continuously to bolster up the clay and prevent its erosion. This is rvhere the colossal expense arises. Gaps should, therefore, be reduced to a minimum before stonework is started. This is a matter of trial and error. A similar process is followed on both sides of the main closing gap. Both ends are pushed out till they are eroding as fast as they are built. Beetles are a great help in making firm ends, but must be immediately sealed in rvith clay and built up r.vith sand behind. (Photo 13.) If rough weather arises the end of the dyke must be revetted with clay and mattress facing. Sommerfeld track was useful for quick work here. No cross walls were built in the dyke. This I ahvays felt lvas a mistake. If a storm took the end off a dyke (once lve lost 100 m.), many hundreds of thousand tons of sand ran out of the dyke and the sea came in quicker to erode the clay lvalls from both sides. It tvas, however, a race against time and these cross rvalls could only be done at the expense of prolonging the dyke. No clay core is built in traditional work. Finally the gap reaches a point at which the cheeks can stand no more pushing out, say 80 m. The bottom has been mattressed. This should be done for a width of 120 m. minimum. It lvas first done for onlv 60-80 m.. and rve had several failures. the vrater poured over the knife edgl, formed a scour, and the knife edge collapsed. Stone is then dumped on to form a firm dead level bottom. Up to 60,000 tons of stone may be needed, and this is usually the difficulty. Absolutely firm doorposts have to be made and it would be the qreatest help if these could be square on the inside vertical face. " Intermediates " tronld be ideal but we niver had enough. Beetles were used, but there was ahvays part of the gap with the slope of the clay. In one case we built in tu,o 600-ton ships to act as square doorposts. At our first attempt we tried to put in several Beetles at once. This rvas too complicated and failed. We finally succeeded with a ship between the

doorposts. This ship stayed rvhen the dyke rvas breached laterithe doorposts

having washed arvay and the closing ship having to be used as one of the nerv

doorposts. This happened at trvo gaps. Eisewhere tve tried with a ship overlapping the doorposts by about 3 m. This was successful. In one case the ship came from the sea side and in an another from the land side. This is I think immaterial, and depends on the ease of manceuvring in, the sunken wrecks, and the position of holding

anchors and winches. At Veere, where there was a most skilful resident engineer, they let in tq,'o 400-ton German ships, each 44 m. Iong, at the same time, and butted them end to end. This is tricky, but lvorked. Ample Beetles rvere available, both inside and outside, to run in and stop holes. (Photos 19 and 20.)

THE SAVING oF WALCHEREN

Ships must or

gn powerfur machine-operated .rvinches: f: ,l if possibre ai";:T?,Fj'X,l;'t:.:*, *iq.q1. i;; ",h* -..9,."*r.: t,act6,s, not with .r.",J ",""..forress than tr,._r.r u". t J n:".i.i":if movins " L1,jlre ",:,

','il, ilTit*djr:i*r:il,l:*t1,if si"*'"'o; i"i{:,,x;lt#J''i,,Hiif, ed po.,,',d, th. turn

d.ecid

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**: _"i,TlilTl iil 1;n$:*lild,###r:..., and, convenient ,o.n ,,,..u",e m in

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*fS:":'""1"T:iJ"H,i'"'oo',"d:,1"t;;ff There is no need

fg:'';,;;fi{ffffi ;{,},Tiiitflf:,.?;:i#*r,,*;n#; j.fr

';r,*

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j,j:$i:+Ti:itrtT:f::.i.iuia*,r,.i

tr"li'*"::l'Tiii,""r.**iti:i:t:'+ilr-::shut'c-ompreterv'rhereis

$li$illii+l#;:i,[:"::;{i,ffi weather o' not

ttit-;,i,f"l{ijli,':::""1'"1{ff u"uuttt

brtu ght " t'rlf, ,]I[f.fi r3;$ ".,ou!r,'.t' "X;tTf !' r*. r'"n J'r", sh ""'',:;I[:!q,hqiil:,1"'f ']X,ff '*"t i jf]hore ip is st ;:'!3'3:::i::,f'lll'! iliJ''i'*";li:;fu 1,.^ l*:., imp oi,un ".,o n l,h e Sf \;,,1111",}; f * 1'11s. *5 r," a r,.i" i a " ;il d,l?}#]i: jfr: ff U:l 1o

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m e ticu

lif

gap is

" s a re one or the most m ovins f";

o u

o,suni

r^ti

o'se

:_r.4i;giF;,.;:F"x*il3:[:it1i.ff must.be.;;;p;;;

i:::,1*Tr"jJfl.":lp;"

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that those inside the gaps

wlr

il:JirJ'r'#?,;i.Htilt:,ii*rlrti j*t:JrXT [xfr .TIXTff ff

*'ji{tri,:atirrllYi:

,.::i .

i :::.

i::r

\*l

Photo I8.-WEsTKArELLE. P.C, Pontoons just appearing on top of an Intermediate

Photo rg,-VrBnr. Trvo ships coming in from the sea side simultaneously. In this case the borvs were butted to the ends of the dykes and there rvas no overlap. Note the cables for the inland anchors *'hich are not yet pulling, held out of the *'ay by the grabs.

Photo zo.-\rarnn. Betrveen the t*.o ships.

Photo

zr.-Vnrnn. Fully

stone barges

opened Beetle coming

in twenty minutes after slack $'ater. Note the

INSIDE the gap as reserve. All were used. Suction dredger is already shooting sand. Foreground, Prof. Tnvssn of Delft University.

:'1d!iiir.l'

Photo

zz.-Nolrr. l8 million

t!r:.i

cu. m. oer tide rush in.

di&*;es.:- i*$S:,t:l::..i::

Photo 23.-NoLLE. The steel ship breaks her back and sits dorvn absolutel,v firm. A concrete ship would have left a hole underneath rvhich might have scoured.

i,,:

Photo 24.-Nor-r-E. Victory in sight. Note the

Photo 25.-NoLLE, Success.

hear-y-

boulder clay.

THE SAVING OF WALCHEREN SrzES oF

Westhaoelle.-Two rivers

Gars (Aucusr 1945)

:-The first 30 m. rvide and 2 m. belorv

N.A.P.

was easily closed. The second gap reduced to 60*m. v'ide, 7 m. deep, with difficulty. Through these flowed in 5 million cu. m. per tide.

Nolle,-IlD m. wide and 4 m. deep. Finally closed as a gap of 35 m. wide and 2 m. deep. Through this flowed in 18 million cu. m. per tide. (Photo 22.) '

Veere.-After closing 2 minor rivers there remained :-One river 100 m. 'fhe 'lvide , 4 m. deep and a second river 100 m. wide and 8 m. deep. ^The first river was closed without a ship, except for a few Beetles. second river at 90 m. wide and 8 m. deep. Through these flowed in 14 million cu. m. per tide and out 26 million cu. m. Rammehens.-One river at 50 m. wide, 6 m. deep. A second river 100 m. wide, l0 m. deep, and a third river 60 m. wide, 6 m. deep. The third river was closed without a ship. The first and second rivers were closed with gaps of "60 m. and 45 m. and depths of g m. and 4 m. Each tide brought in 21 million cu. m. (Photo

29.)

Plate 26.-Fis.

THE SAVING OF WALCHEREN Sronv on rHn Geps

Each of these was an epic, and each quite

in detail.

NOLLE. Fig.I A. Gap

-of

(See Plate

26.-Fig. I

difierent. only trvo will

be shown

on page 17.)

22 August, Lg45 12'0

m,. Groups of eleven and three

Beetles positioned and the

Five Beetles were ready to be put in. These five took charge and went straight through the gap ind endei up a mile inland. gap. reduced to,25

I B. 27 August,1945. Spring Tides The chain of Beetles bloke up, the end of the dyke eroded, and the gap inc^reased to 160 m. This was our first failure, and l.r.on. we must have a firm end and all ships must be built in at once. we could not cornpete with 5 Beetles simultaneously for closing Fig.

Fig.I C.

3 September,Ig4S

The dyke ends were pushed forward with built-in Beetles from the Flushing side. It must be remembered that the other side was inaccessible

to the suction.dredger. ,The gap was reduced to g5 m. and closed by a steel German invasion ship, about 40 m. Iong. (Photo 28.) This succeeded and the 9!1p was r.apidly built in, grabs with itay and stone pouring in their stuff.

Photo

10.)

Here undoubtedly we were luckier than we deserved. It will be seen that the five Beetles on the far end were still totally unsupported, as we could not get sand,there and we had not been wise or rich enough, to put unsupported clay. (Photo 24.)

Fig.

I D.

24 September,1945 Work went on very rapidly. All was built in and the dyke raised to -F-4.2 m. i.e., 2 m. above normal spring tides. On 28 Septembei, a S.W. gale and exc-eptional springs swept over the dyke, washed-away the sand aid took out the Beetle.s (not the long ship), and lve were back to a Bb m. gap. This rvas rapidly revetted whilst we made a plan. This was reallv bad iuck and most disheartening. I feel that if we had set out sommerfeld track over the top of the dyke, driven in holdfasts, lashed down on top the heaviest rails we.could find, we might have saved it. You have to be feady night and day, and labour must be at instant call.

Fig.2.

2 October,l945. (See Plate 27.-Fig. 2 on page 19.) Quick work. A Thames_barge (specially prepared as a landing craft), which rvas a pretty useless affair, was put in,-and we tried to build lft i. "!. from o_yr next great lesson, where gap closing differs fundamentaliy )y1s_ " Mulberrying." You must make an exact cloiure, any idea that eveiy solid ship is a help, is quite false ; it only increases the speed of lvater in some other place where you can do nothing about it. Meanwhile an J' Intermediate " had arrived from England. We hastilv prepared this for demolition. More mattresses and stone; were sunk to give us a bearing, and all possible clay and torpedo nets collected and lve decfued to sink in front of the gap.

il;.ir[]t

r-:r.t

l:triil;:i

THE SAVING OF WALCHEREN

Plate 27.-Fig.

It sank beautifully in 2 minutes according lo piul.. Immediately the triangles at the ends b""u-" dangerous and rvater hurried through threatening to .t"od" the dyke ends. HerJ we first used torprdo netting, and it $'as immediately u.rrcc"ts, holding the healy imported c1ay, and lve began to rvin' The water was also breaking through underneath and we _were frightened of it scouring right through. Two Beetles were laid in-(fortunate.ly they wefe on the land Jide of the gap) in the hope that they rvould, be sucked under. This happened more or less, and the grabs poured over clay-to jam among them, and the dredger poured in sand to back up the clay.. For four hours of lor,v tide the large grib was too far off to reach over the " Intermediate," and lve only had one grab in action. As the iide rose it poured over the top of the " Intermediate " and threatened to scour out behind as it fell over. More Beetles rvere needed, but there were no more inside the gap. I offered to puIl them bodily over the

too of the dvke farther back, with a D.8. The Dutch were, however, frightened of"spoiling the dyke surface. some N.L. pontoons.were_ Iying in"Flushing; tLese iere bofted up into strips rvith the whaling boards that

THE SAVING OF WALCHEREN belong to them, floated up on top of the " Intermediate " and clay fiiled. They just did the trick. By 4 October the dyke was safe. (Photo 27.)

RAMMEKENS.

(See Plate

28.-Fig.

3.)

Fig.3 A. 15 October,1945 It will be seen that there were two rivers (Photos 29 and 3l) ; also that the places selected for closing were not on the line of the proposed neiv dyke (Photo 33). It wiil also be seen that two colossal holes existed, 8l ft. deep on the sea side and 5I ft. on the land side. These were a perpetual worry. We feared not only that they would spread, but also, ifwe piaced too heavy a load ol _th9 " knife edge," the whole " knife edge " would cleave horizontilly and slide into the big hole. We believe that this is what did happen. The whole bottom was built up with mattresses and stbne to a heieht of 8 and 3.5 m. respectively, and of widths up to 60 m. and 45 m. as tf,o*rr. This was a very long job and used up 60,000 tons of stone. The " island " was then made good by a grab digging out alongside. No clay shell could be made here and sand filled, since the pipe line could not be carried over. Means.hile a third river at the west end (Still water in Photo 29) had been closed by traditional means, enabling the pipes from the trvo dredgers to reach to each side of the gap and forming a still water harbour.

Fig.3 B. I December, 1945 Two Beetles were fixed as doorposts in the east gdp, then 35 m. deep. This was eventually closed by a 4.5 m. high German ship simultaneously rvith the last gap.

The last gap was still 8 m. deep and it was clear that nothing less than a " Phoenix " 12.5 m. high, rvould do. The two cheeks sloped down at I in 3 and promised a nasty triangle to w-ere

put in

fill.

Our two last

" Intermediates," of steel

as doorposts. One.slipped and disappeared and was

not found

for some days, in fact we thought she had gone through to Australia ! This was a diffrcult gap. A second doorpost of two ships was put in and stayed in position.

On I December, the first magnificent great 10,000 ton " Phoenix " sailed in and was sunk. This was our last gap, we had all our previous experience behind us and had massed all the great equipments for this one task. It took place in fog, visibility 500 yds., and it was a most impressive sight.

The organization by which tows from the open sea, each with up to 8,000 tons of stone or clay, appeared through the fog, was marvellous. Flags flew, hooters blew, gin flowed, and we really thought the battle over. Even our English sinking master, Maj. Cramp, on the " Phoenix " was

*t;Sf"t.

Five days later the " Phoenix " rvhich had been 2.5 m. above high tide, just disappeared I (Photo 34.)

Fig.3

By 15 December the

whole island and the " Intermediate " pontoon dooipost went. It was still a difficult gap ! We were now left with the sinking ship from the West gap as a doorpost, and a small portion of the " Phoenix " showing at dead low tide only, as the other doorpost. I do not think, in this case, that the " Phoenix " could possibly have punched right through the stone and mattresses, nor is it likely

ijii#dij

';'

THE SAVING OF WALCHEREN

rbth

ocrogER

DECEMBER

teas

'rll -',/

t e45

fAscrNE l{a-rTaEss€s

tsrn oEcEMBER

AXIS N€W DYXE

24,th JANUARY

NEW FASCINE HAT]

SECTION A-A

RAMMEKENS CLOSTNG FINAL GAP Plate 28.-Fig.

THE SAVING OF WALCHEREN

that the big_ hole scoured out and undermined the knife edge. It is more Irkely that the whole knife edge side-slipped bodily by cleav-age on a lower stratum. ,, "

lolg .period of remattressing and stoning then began. The old *Phoenrx " was heightened 4 m. by building

on two layers oTp.c, pontoons gunwale. This was a tricky job and only poisible by !y the fact that the water could flow through the gap freely. Meanu'hile a third suction dredger was set to work and sa'nd poured in.to make good behind everything ,ni to try and fifl the i.o"i *h t*L as.a

]l:l:.-1,lpC,.,her, very skilled men and holes.

Fig.3 D 2.1,Jnt"ary, a new ".Phoe.nix " was brought in carefully, not overloaded, -in

__9n wrth and

rt1. wliSn! adjusted to the tide as explained the para. on rnoenlxes." trig insurance was available:-Three large grabs, a special -" steel flap on the Phoenix,",unrimited. good clay, zod t8"r-orlorpeao netting.from all over Europe (some__of it"only arrived tt" ^o*inf ,ir z+ January), plenty of stone, and the will to win. .,,T1. 1lo.i"g was successful^and by 6 February ne could definitely say

walcheren was saved. (Photo 32.)

Dr-rroontNc

on 6 November with the successful closing of the veere gap, the bulk of the island 'rvas closed and.safe. Fpptting_trte water was e*ir.mely simple ; that ferv people believed it.- The lock gates_to the canal ui Fluri-,i'g :: :i-ql. and at veere were closed. The canal water was brought up to the island water level. The canal bank was breached by bulldozer"s foi tzo m. A tucket dredger deepened this. easily, since it wai working in static water. The hote was revetted on the bottom with mattresses aid stone to prevent scour. The lock gates werc opened and the water flowed out. On the'rising iiOe tfre lock gates swung to, and remained shut till the sea again became l6wer. In twelve days the island was dry. The small Rammekens arei had to be pumped out. This took five weeks asfhe suction dredgers filling the hole were itill pouring in water with the

_.]va-lcheren is now dry after 15 months immersion, and is a tragic sight. The hor"rses are covered with mussels and impregnated with salt] Thos" with lime mortar foundations have suffered most,"but generally two-thirds or more can be made good, The main Middleburg-Domburg road was merery singre bricks on edge on a sand bed. It was always two to five feet undei watir and continualiy pounded.by heavy_ D_ukws. The repair oj underwater potholes in pav6, is- a problem for which no ready solution offers itself. suiprisingly .n^ougt 90 per cent of this road emerged perfectlv good. A11 vegetation is dead and a volume .ouid"be written on the time lag for new crops. _ There is no scientific agreement. one thing I think is ceriain, that deflooding must.only be done in winter when precip"itation exceeds evaporation. If the sea is allowed to come_in. freely the land can never get saltei than sea water is salt. Even this is not fully agreed by the soil chemlsts who claim a structural deterioration of the soil. ln ts+o there was actuallv a successful crop of wheat on part of the reclaimed land.

Photo 29.-RAMMEKENS

The two rivers scoured, with the third river on the right alreadY blocked.

Photo 3o.-Four-ton Grabs.

Photo 3r.-RAMMEKENS. Lotl, tide, one of the rivers.

Photo 32,-PuoENrx. ro,ooo tons pushed by seven tugs.

iititjiil*g!,iLirit"t;J:ir:r:,,_:l:L:!:i:,: j.

Photo 33.-General vierv of Ral,nrrxENs, 6 December, 1945. Pipe lines from trvo blorvers on trestles.

ih*fJ'i'"-*.iqilkhTt,Tfl lf tr!".';:?l:*"-j:*ni:*ixtr:lr#vi,:f:i*:*

THE SAVING OF WALCHEREN

:'!:-

Cosrs These have been very high, but great disasters need powerful remedies. {1,400,000 The Dutch spent in labour and small stores on site d200,000 Stone from Belgium cost '*. , bY us Major plant -qtnreslent

{160,000

Mulberry EquiPment Ec O.S. nquiPment ClothinE and O.S. Clothing Clay from Moerdijk

{490,000

[,{ii^. stores, Minor

{I06,000

as cordase cordage and tools

d19,000 d300,000 d100,000

Brushwood

Lasoun

No account would be complete without a reference to the labour force.

About 1,200 were outsiders from the areas in the mouths of the greatrivers' worked r'vith their cus1' t.." i".i"aed about 400 brushwood workers, who skill. traditional unique tomarv "

contractors, bargei;i" Sgd o1 the outsiders were tug masters, cranemen, rvas superb,and th"ey never *;:;;J'dr"dg.. .r.out. Their sJamanshipunfortunate legacy. from tire r""..a themslvEs. There lvas, however, an unaccountable some were ;[;;;,i;;^il .t".uutio" p.riod, and there of closing. There rvasstrikes, a big criti.cal moments ;;;.';;;;;"ilu."i"t.iv clothing cante,ens and

providing welfare task in .protective Every other *?ek-.nd haJf the force had to be taken home for these men. "".o*moditing, special trains weie produced by the British' and -"ih;; per cent i;;-uUo"t t,iOO murrrri rvorkers who rvere almost 100 lntiring' persevering' dogged, most Walcheren Islanders. They lvere the irJr.1rio,r. workers I have Jver seen. Their islant wai at stake and nothing

*u.

too much for them, cold, rain, and sea; day and night'

is not only by Toil but also by great coxoage, Islini of Walcheren wa{retrieoed from the Sea, lihe a ship batteied in a Tempest, but neoertheless, sailed on^its course towards the Light of Tomorrou'

that the

February 1946.

(Den Doolaard.)

j . ._-._

:. ::