,$..,WC,, THE SOCIETYOF NAVAL ARCHITECTSANO MARINE ENGINEERS 74 Tr,nityPlace,New York,N.Y.,10006 ,+’ *% Papert. he presentedatme Sh’pSt,.ct”,esyrnpxl.m 8 ~e Wmhi”@on,D.C.,October6.3 1975 c+, (ii ? o% ,~“,,*,.+. Observation of Ship Damage over the Past Quarter Century H. S. Townsend, Member, United States Salvage Association, Inc., New York, N.Y,

6>COPY@ht 1975 byTheSociety.fNavalAmh(tectsandM..,..Engineers ABSTRACT

This paper treats with ship damages taken fyom surveys of the United States Salvage Association, In. ., over the past quarter century, on vessels of all flags.

Insofar as U. S. flag vessels are concerned, the period involves the mid- life and concluding years of operation of preponderant numbeys of the well– known World War II standardized design vessels. Ce~tain of these types showed some common inadequacies; others showed propensities fortunately peculiar to themselves

In the early 1950, s the supertemk- ers of 28–30,000 tons deadweight came into being, as did the llMarine~,,class of dry cargo carriers; subsequently, in the early 1960, s, Illa~yof the U. S. sub- sidized oper-ators commenced laying up the World War 11 types, and filled out their fleets with vessels specially de- signed for their specific trades, with multiple units bein~ constructed from the same design. Certain of these “es– Sels suffered some of the weaknesses peculiar tc,the Wcrld War II designs

No sooner had the specialized dry cargo “essels been put together than the container revolution came upon us , which created considerable conversion in existing ships and thinking. Als0, the the sea rose up and smote the ship huge tanker revolution commenced after’ the mid-1950, s. CASUALTIES OF U. S FLAG With all of the changes, how much wORLD WAR II BUILT VESSELS relay of operating exper-ience was ti-ans- fer~ed from one Erowth pattern to the The United States merchant marine next concerning the faults of the var- following Wo?ld War 11 was comprised of ious types? What has been the cont~i - large numbers of a relatively small nunl- bution of research and technology? ber of types of vessels, mostly built during the wa~, irlthe general cargo and This paper sets forth and treats tank–ship categories. with , and in certain instances illus– trates, specific inadequacies; it in- Fron this circumstance common dis- cludes observations on what has appeared orders were easily ascertainable, and to haw been inadequate communications very definitely oft–repeated failures i“ the past among the disciplines in– showed patterns not only for each type Volved, makes reference to today, s cir– but across the board fo~ all types in ,cumsta”ces, and makes some suggestions similar’ trades , i.e. , all general cargo for the futui-e relating to technolo~y. ships, or all tankers.

. !,-1 The types treated herein embrace steps taken (where applicable to pre - the Cl, C2, C3, Cti, Liberty, Victory, elude repetitive failure), are presented and T2 Tanker. Certain of these types in the following, which by no means were designed prior to the U. S. entrY should be considered to be a complete into World War II. and were a Dart of summary the general rebui~tiing of the ti.S. merchant marine beginning in 1936. Failure of Longitudinal StYength Members Some of the problems peculiar to the “essels considered here, and the A common disorder was fracturing necessary repairs and/or corrective of structural members contributing to

Fig. 1. Attempts by the crew to pre”ent complete hull fracture

L-2 + Fig. 2. A complete longitudinal failure of a “T2” longitudinal strength due to structural tanker. arrangement which caused local areas of high ~tress. Structural arrangements such as square hatch cutouts in deck plating Figure 1 shows emergency measures were eliminated by inserting radial taken by the crew of a “C3” type vessel shaped plates in the hatch corners (1) to prevent complete girth propagation Doublers were installed in way of square Of a shell fracture, and FiguPe 2 house corners Discontinuities in lon- shows the complete failure of a “T2” gitudinal members, such as resulted from

L-3

!--- the cutout for the accommodation ladder lo”git”dirml and ti-ansverse forces, fast in the bulwarks of the l’LibeTty ’ttype, fractur~ am-est , computer programs, full were eliminated. scale measurement programs, thermoplas- tic model studies, temperature influence !,Crack ~rrestor,, straps were in- studies> etc. References (7) and (8) stalled on deck, gunwale, side shell, provide indices which include such works bilge shell, bottom shell, etc. , to emhi-acing 1946 to 1969. preclude complete girth propagation of fractures in deck and shell. Relating to compressive stresses in the bottom shell. and restricted to the Ihmbably more than any other type transversely fraked vessels, was the uP- of damage the fracturing of structure ward buckling of the bottom shell be– cor,tributing to longitudinal strength tween transverse floors, largely within influenced the formation of the working the midships half length, the phenomenon groups, panels, and committees of the comnmnlv called “hin=intz”. which was a interagency Ship Structure Committee, direct ;esult of hog~in~ Lending mo- and the SNAME Hull Structure Committee. ments (In (1) the phenomenon is Doubtless the theatrical impact of the treated with respect to the “Liberty” types of failures involved, particular– type ) lY where complete failure of the hull girder occurred, often with loss of The bottom shell in way of the life, had much to do with the emphasis ‘hinging” experienced a significant placed on seeking solutions to the Pro- thinning in way of the unsupported span blems, which, fortunately, were found. nominally midway between the transverse Pe,.ti,,ent are (1) through (6) which are floors as contrasted with the thickness but a rew of the pursuits stemming from of the’ shell immediately adjacent to the individual efforts under the auspices floors (Invariably this factor was not of SNAME, classification societies, taken into consideration in presenting etc. , and in addition to which must be records of audigaugings or drill ings to added the staggering quantity of re– establish bottom shell thickness es.) ports under the auspices of the Ship Figure 3 illustrates the “hinging” Structure Committee on works of unique phenomenon Quality relating to establishment of

Fig. 3. Typical hinging damage

L-4 . The bottom shell plating required expected longitudinally framed vessels, renewal in the worst affected areas, such as tankers, did not suffer the and often the new plating showed the sickness. tYPical upward indentation between floors, without significant thinning, If a system of ti-ansverse frmnipg after only a short period i“ service, is to be utilized in the bottom of a perhaps because of the 10SS of resist– vessel it is obvious that the number of ante to compression from the neighbor– lon~itudinals , and/o~ the thickness of ing plates which showed some hinging, the bottom shell, within the midships but not considered sufficient to re- half len~th. must be Ei.Ie” more consid - quire renewal when the new plating was eration ~ha~ was the ;ase with the world installed. WaF II types

In a few instances intercostal It is also rathey ob”ious that lon- longitudinal flat bar or inverted angle gitudinal framing in the bottom and deck stringers were installed between trans– of a “essel (with t~ansverse f~aming for verse floors, breaking by perhaps one. the sides to reduce docking damage ) is a third the transverse span between ex- more efficient structur-al arrangement isting longitudinal girders, in an than complete transverse framing. effort to put a stop to the phenomenon. The longitudinal stiffeners intercostal Slamming Damage to the floors were of two “arieties : one had ends fixed to the floors, Lhe All the general ca~go types except othe~ was cut ,hoyt of the flooi-s, be– the “Liberty “ type suffered indentation ing wholly supported by the shell im– of forward bottom shell and buckling of mediately adjacent to the floo~s In a internals , and in some cases secondary few rare instances the bottom of the damage to kingposts, piping, machinery, intercostal members was sc~ibed and cut etc. , from slanmi”g Figure 14il.llls- to fit the upset of the affected plates trates typical slamming damage to ~or– ,ward bot Lom shell pl.atin~. It is no LewOrthy that as might be

● Little structural addition was stren,qth shell plating can be utilized made to reduce the frequency of this with the existing spans, keeping in mind type of damage. that the internals failed when the high strength steel plating was used for the In one instance of damage, to a bottom shell with or’iginal internal UCZ,,type vessel, high strength steel spacing. was used to replace damaged shell plat– ing on one side and the keel plating, As a matter of interest the records while o~di”ary mild steel was utilized of the United States Salvage Association to r-eplace damaged shell plating on the show practically no slamming damage on opposite side. After one year! s oPera– the “Liberty” type (often forward- tion the high strength steel was unaf- located hinging damage was confused with fected while the mild steel plating slamming damage on tbe type) showed severe damage; however, the area of the VESSC1 in way of the slamming Additionally, tankers, including damage was bodily set up 1%” above the the “T2” type, did not suffer from slam- base line. No repairs were made then, ming damage, doubtless due to the fact but a yea~ later, after two years Oper- that tankers can be ballasted down. ation subsequent to the installation of the high strength steel, again no dam- An indication of the frequency, the age was found to the high strength location, and the cost of repairs of steel plating, but the damage to the slamming damage for the vessel types af- mild steel plating had been aggravated, flicted is covered in (9). The damage and the bodily set-up had increased to inva~iably affected the keel strake, and 2kJ’above the base line. str’akes A, B, C, and sometimes D, the damage by no means bej.ng limited to the FIJI-reasons unknown to the author flat of the bottom. Local indentations this striking experiment was not made aS much as 4“ were observed. Damage to known to the technical f~aternity, internals usually was not too severe, which is unfortunate, fOP some extrem– and where same occurred it generally ely interesting aspects were a part and ~elated to buckling of the lower part of a result of the pursuit, not the least the transverse floors and the center of which was proof that to prevent in– vertical keel. Figure 5 illustrates the dentation of shell plating from the in- internals of the vessel with the shell fluence of slamming either the unsup- damage shown in Figure b. ported span should be reduced, or high

I .

Fig, 5, Slamming damage (same ship as Fig. 4 ) showing minimal damage to internals

i- L-6 !!’–– .SNANIE,s Slamming Panel was formed (often also installing doublers in way) , in the la Lter 1950, s, and under its ~u5– or to replace affected material with pices (10) was p~oduced, in which a sound metal Access staging costs were se~ies of hull forms was presented as always a significant part of the ~epai~ hopefully representative of forms which costs. would develop relatively low slamming impact pYessuI-es, this being achieved In efforts to minimize recurrence with the one fullness so far investi– of fractures, where structure of simi- gated (11). lar disposition and amangement was reinstalled, replacing failed structure, In (17) there aFe p~esented Val”e S some owners specially coated the struc– to predict slamming imDact forces for tural internals in an attempt to pre– various vessel for~bod~ transverse sec- vent thinning; however, except in a few tion shapes. isolated cases the internal coating of tankers did not really catch on until Reference. (13), (14), and (15) the new middle bodies ~ere fitted to are simificant cont~ibutions of the World War II tankers. Ship S~ructure Committee to the pursuit of the subject of slarmning. By the time the “Jumboizing” craze hit the U. S. merchant marine enough A currently proposed pursuit unde~ had been learned, and fortunately pas- Ship Structure Committee auspices is sed on to most of the design fraternity, di~ected to the development of imstru– to inco~porate structural ai-rangements ments to measure, simultaneously, im- other than those which had led to fail- pact and ?elati”e velocity of ship and ures in tbe first Dlace. One has onlv wave. The program is aimed at correlat- to look at cu~rent’ practice in the de: ing forward bottom and bow flare impact sign and construction of t~ans”erse pressures measured on ship and model, and longitudinal bulkhead arrangement , and is fundamental to a bette~ under– web frame am.angement , the methods of standing of the problems. easement where flan~es and bulkheads make up to associat~d st~”ct”re, etc , Tanker Internal and compare it with the standa~d World Structural Fr’actuFes War II tanker str-”ctural am-angement, to achieve m understanding of the rea– The fracturing of the internal sons why f~actures were so commonplace Structural members of tankers wa~ com– i“ ,Worl~ War II tanker tonnage kee mon. Such styucture rapidly reveals (16), (17), and (18). configurations and arrangements which lead to fractures since corrosive at– Figu?e 8 shows the marked change tack is so standard in the trade in struct”?al arrangement for a ‘rJumbo” Co7rosion is accele~ated in areas of ,,Tz,, from original 11T2!,arrangement hi~h stress, and such !thard spotst! were common in many of the internal struc- Tanke~ internal fractures are tural arrangements of World war II still with us, but not at the rate of vintage tankers Hard spots were found the 1940$s and 1950, s. i“ web frames, brackets joining trans– verse bulkheads to longitudinal struc– Side Shell Damage ture, connections between transverse bulkheads and longitudinal bulkheads, Side shell damage, consisting of shell longitudinal stiffener penetra- the setting in of shell plating amd/or tions through transverse bulkheads, internals , afflicted all types, pri- tripping brackets, etc ma~ily f?om docking and from collision with lighte~s alongside. Little or Fluted transverse and longitudinal nothing was done to design OF rebuild bulkheads showed a consistent propen– against it Structure was replaced as Sity to fyactuye in way of whe~e the befo~e. In many cases the damage was metal had bee” originally stressed in way of ref~igerated spaces and Fe- beyond the elastic limit to fcrm the quired most costly removals and re- corrugations The circumstance became placements to perform the ~epai~s particularly e“ident whe~e ad”anced co~rosion obtained. Figures 9 and 10 a~e representa- tive of typical side shell docking/ Figures 6 and 7 present the struc– Undocking damage tural arrangement of the !1T2,,tankez-. The fluted bulkheads and hard cornered Damage to Castings configurations will be noted. Castings, employed on all of th, Short of completely replacing the tYPe S, Presented an unpredictable ser- bulk of the internal arrangement which vice performance. This pronouncement led to fractures, the owners followed stems from observation of the “se of the only course open to them, which was steel castings in ser”ice for stern to chip out and weld the fractures frames, shaft bossings and slee”es,

L-7 3$21 2 $3 4 5 $ 6 7 8 ,-

U 1[

Fig. 6. IIT211 structure (center tank)

L-8 - &---

j I

? ‘ ,

k------‘J’’””””$’ ------.d

Fig. 8. Typical structure prOpOSed for Jumbo “T2” (Ref. 16) and a myriad of uses in the machinery riveted ship construction to achieve the category. compound shape forms for efficient hy– drodmamlc flow. Few World War II vessel stern frames survived without showing frac- “Thermit” welding, and “Metalock” tures which required chipping out to were , and still are, means of joining sound metal. which often disclosed fractured pieces of castings, and many further imperfections such as shrinkage repairs using these methods weFe made fractures, porosity, inclusions, etc to avoid the expense of the replacement . See Fi&ure 11. of an entire casting.

When a major damage occurred (see Obviously the disadvantage of a Figure 12) which required the replace- c~sting is that it does not lend itself ment of even a section of a cast steel to the cropping feature of welded ship stern frame, the repair cost was enor- construction. mous. One would ask then, why were . castings utilized in the ends of ships, ,,L1bertyv Rudder Problems where the shell plating draws together and presents of itself massive strength? The “Liberty” contraguide rudders Perhaps it was inertia, stemming from showed vulnerability to excess wear of wooden and riveted steel construction, the wood bearing above the PuddeF, fFac- or at least a throwback to an era of ture of the rudder tube (stock) , and preweldment construction when castings fracturing of the rudder plating and were the easiest method in i?on or steel welds in way of the division plate.

“-’+ L-10 1 1 Fig, 9. Typical side shell damage

Repairs consisted of replacing the of underwriters or, specimens of tail - wooden bearing with a bronze bearing sh;,fts taken from in way of the frac– arranged fo~ lubrication f~om the steer- tures, an?.many vayyin~ conclusions ing flat, welding up or’replacement of were reached relating to the causes of the tube, and reinforcing the rudde~ in the fractures Some concluded that Pro- way of the division plate with angles peller impact led to the failures; how- and straps ever, many concluded that fatigue was the prime causation, particularly in Tailshaft Failures the case of circumferential fractures just ahead of the propeller, indicative The incidence of fractui-ing of of failure in cantile”e~ed bending. In tail shafts , either circumferentially some Tel,ati”ely rare cases the tail– ,just aft of the liner. or in way of key- shaft material was founclto be at ways was alarmingly high foF ali types” fault of vessels See Figure 13. In an attempt to reduce the recur- Where there was propeller dama~e i rence of fractures in way of keys the was invariably alleged that a st~iking keyway configuration was altered by Caus?d the f~actu~ing. “spooning” out and generously radiusing the shaft material at the forward end Literally hundreds of metallur- of the keyway (Figure 14) gical examinations we~e made on behalf ?--- L–n Fig. 10. Typical side shell damage

Numerous repairs to shafts were cure was to install a propeller capable made by chipping or grinding away the of absorbing normal full power at re– shaft in way of fractures, and replac– duced RPM. ing the ~emoved metal with weld metal. Unfortunately, for all of the Where the tailshaft was condemned types considered here, in order to r-e- for furthei- service, this invariably move the propeller for even the simple led to the r-ewooding of the top and bot- examination of the tapered end of the tom halves of the stern bearing to ac- tailshaft, it was necessary to with- commodate the diameter of the bronze draw the tailshaft into the vessel, a liner on the newly installed tailshaft most Iaborous and expensive procedure, and further, if it was necessary to The “Libertvl! tailshaft n~oblem. remove the tailshaft from the vessel, which in many Ca;es In”olved khe com~ it was generally found less expensive plete fracture of the tailshaft just aft to make an opening in either the shaft of the line~, and 10ES of propeller, was alley or the shell to accommodate this found to be related to a third oi-der removal rather than to attempt to move torsional vibration. cr’itical at about the tailshaft Into the engine room 78 RPM when the vesi+els were light, and spaces and out through the fidley. See at about 70 RPM when loaded The USUal Figures 15 and 16. — L-12 Fig. 11. Typical fracture in cast steel stern i-pame

Had the designers of these vessels time consuming and difficult procedures been aware of the tailahaft problems which were a part of the propeller and which arose they most certainly would tailsbaft problems of World War II have arranged the Vessels such that at stern gear arrangement. least the propellers could hawe been I.e. moved without drawing the tail,shaft in– Stern gear arrangement is as much board. a Part Of the naval architecture/ strength of materials discipline as the Today we find many vessels which marine engineering discipline, and it can accomplish the immediate abowe, and is mentioned here for obvious reasons also we aye blessed with the development of a satisfactory seal allowing for oil Tail Shaft Liner Erosion lubricated stern bearings which void the necessity of a bronze liner; some of the A phenomenon which showed up with arrangements e“en allow for inspection no regularity, and appeared to affect of th~ tailshaft forward of the’propel- only a few of the vessels here treated, ler, afloat. of all types, was tbe appearance of longitudinal bands of erosion on tail- We are also blessed with the de- shaft liners . radially located nominally velopment of the ,,pilgrimptnut and other between prophller bla; es. hydraulic arrangements which amid the L L-13 Fig. 12. Major damage requiring replacement of much of a cast steel stern frame

Many theses were advanced to ra- ability to such damage. tionalize the existence of these bands of erosion, ranging from water pulsa– COMPHJNICATIONS BEFORE, DURING , tions through the bearing, eleCtTOIYSi S AND AFTER WORLD WAR II taking place from generated static electricity or galvanic action, etc. Surely neither the designers nor In one instance it was even alleged the builders of the World War II types that the damage was caused by the ves– were aware that they were building in sel lying in contaminated waters. weaknesses.

It is believed that to this day no Further to the foregoing, and on positive knowledge is at hand as to why the subjects of slamming damage and the phenomenon occurred; however, the hinging damage, both types of damage need to establish the true cause has usually lent themselves to long periods been obliterated by the development of of deferment of repairs, and also the the sealed, oil lubricated stern bear- damage was not of a theatrical nature ing, which fortunately shows no vulner– and invariably was not accompanied by ——-. L-14 Fig. 13. TYPtcal tailshaft fractures, both circumferentially and in way of keyway

10ss of life, all of which simply dld new construction, most owners consider- not lead to a broad awareness of the ed the World Waz. II vessels as obsolete frequency of the damage among the design and not worthy of grandiose, expensive fraternity. Further, the standard bam- schemes to reduce recurrences of the boo curtain which seems to exist be- types of diseases that the owners knew tween field personnel and design person– they were susceptible to. Under the nel was apparent circumstances it is perhaps remarkable that certain owners, who made it their In large measure the owners did business to maintain a rapport with nothing about the types of damage which SNAME, caused pursuits to come into be- occurred except to make repairs in kind, ing which in the long term did lead to or at best respond to classification solutions; bowever, it is clear that recommendations. The very nature of segments of the ship designing fratern- owning one of a vast group of similar ity had no feedback concerning certain ships simply did not lend itself to of the experience even after years of unique or individual thinking. Even operation and failures, and it was evi– though few owners were making plans for dent that there was a gap in the flow

L-15 Fig. 14. Typical tailshaft fractures (shows “spooned” keyway) of communications between the repair di- designed vessels, could have been avoid– visions and the design divisions of ed by better communication; however, in most shipyards. It was also apparent pursuing this we should keep in mind that a means was missing to create a that the U. S. merchant marine jumped flow of information between seagoing from Wo~ld War I to World War II largely people and their own,:rs, and a continu– without any new construction or design, ation of this flow from owners to those and it is remarkable that the flaws were in the shipbuildin& a“d ship design as few as thev were. Additionally. the fraternity. state of the irt of the welded sh”iiwas in its infancy just prior to 1940. One might be curious as to how much of the oft-repeated s,tandar’d weaknesses, shown across the board by so many of the World War II built/

— L-16 a— Fig. 15. The disturbance attendant to pulling in the tailahaft

CASUALTIES OF POST WORLD WAR II VESSELS

Nominally in the oyder of thei~ The ea~lier U. S flag general construction to date, U. S. flag post cargo wssels , when operated in the World War II large ocean-going vessels North Atlantic at least, showed as se- comprised high density ore carriers; “ere a propensity to suffer from slam– 28-30,000 tons deadweight (,r.super,,) ming damage as their World War II pre- tankers; the “Marinert’ class (as general decessors. See Figures 17 and 18. One cargo vessels) ; various classes of gen- class of these vessels, when the Unsup- eral cargo vessels, many of which were ported spa” of the for”ard bottom shell Co””erted either during construction or was halved, showed no further damage. subsequent to constmction to container The balance of the affected vessels have vessels; initial design container ves– almost all been converted from Eeneral Sels : sDecial bulk car’rieys: lar~e cargo service to container serv~ce, and tank;rs’ and ore/oil caFrier~; la~ge are operating at a more nearly constant, bulk cargo barges; integrated tug/barge relatively great forwa~d draft, and have units ; bar~e carrying vessels ; and LNG not shown tbe propensity to damage which vessels. was e“ident when they were PLHX?lY in the general ca~go trade. Abroad, not only were all the fol’e- going types constmcted, but also “cry Certain arrangements of internal much larger tank vessels began to show str”ct”re of the early 7’SUpeFt]tankers, up in the mid 1950,s. after only a few years of se~”ice showed

L-17 #---

!+ Rig. 16. Shell plate opening made in order to remove tailshaft a propensity to fracture, raisin~ ques– avofd fracture.? in the future , which was ti3ns as to whether or not thepe had applied in each wing tank of every ves- existed a proper rapport between ship– sel built with the original construction. yard repair and design divisions some of these fractures related to the cOn– tinued use of corrugated bulkheads in Another circumstance concerning lieu of flat plate stiffened with welded tanke~ structural configuration very vul- structural shapes. nerable to fracture, and related to the fairly ~ecent concept of segregated clean Ship designers 2nd builders world- salt wate~ ballast spaces, is illustrated wlde were feelinz their way with tanker in Figure 20, which is a sketch of a internal structural configurations which transverse web frame in way of the cut- would not fracture in service, and it is outs accommodating tbe longitudinal stif- under stamiable that certain of the con- fener-s of the longitudinal bulkheads in figurations simply did not stand up. the clean salt water ballast tanks, the One such configuration, once again Prov– structme being uncoated. Thinning of ing that stretched metal such as results the structure in way of the fractures f~om corrugations or joggles does not shown was down to almost zero thickness stand up, ~elated to horizontal tie after less than two years service, frOM beams (struts) supportin~ the inboard original nominal 1/2” thickness, which and outboard Dortions of the web frames. thickness still nominally obtained in ~nd the webs ;f horizontal bulkhead areas of low stress stiffeners in the wing tanks of a class of tankers Figure 19 illust~atcs the The failure was a direct result of location of fractures, and aiso the stress set up by fluids on one side of a method of altering the structure to bulkhead only, and resultant accelerated $-- L-18

. ,, I

Fig. 17. Slamlng damage to a post World War 11 U.S. fla~ vessel corrosion and loss of strength in areas VLCC $s , which requirecl that greate~ at- of hip,h stress, causing the metal to tention be gi”en to “eFtical stiffeners fail in shear in way of the cutouts. and their spacing (19) While the cutout configuration fo~ the bulkhead longitudinal s–was the same in Problem. relatin= to damaee to tbe the cargo wing tanks, and the web forecastle head and f;rward up?er shell frames in those tanks were also un. plating of the larger tankers, fro!nthe coated, Lhe massively accelerated thin– effects of the sea, began to show up ning had not occurred, and no fractures even on the 28–30,000 tons deadweight as yet obtained, obviously due to the tankers wbicb appeared in the ea~ly Protection against corrosion by the 1950’s. The damage related to the set- cargo oil. ting down of forecastle deck plating (see Figure 21), crippling of webs and In the segre~ated clean salt water stanchions (see Figur-e 22) , generally ballast tanks there was no Fecourse but accompanied. with the Settinx in of the to crop out and replace affected metal, upper flared section of the-”essel at installing closure pieces in way of the the sides of the forecastle head, and cutouts to help absorb the shear, and upon occasion the indentation of the up– Cl?an the webs f~om top to bottom, and per stem and forward side shell plating coat same. and supportin~ structure (see Figure 23) The damage as a type led to a revamping The pe~formance of the huge tank- of classification structu~al criteria ers bore o“t the fact that great em– for forecastle head design; cur~ently phasis had been laid on longitudinal the affliction appears less frequently. strength, for there were little or no The fact that the navigating bridge was longitudinal strength problems in their moved all the way aft probably had some operation, but this was not the case influence on the frequency of occurrence with transverse structure. Crippling of this type of damage, since those in of huge webs occurred in the early the wheelhouse were so remote from tbe

L-19 Fig, 18. Slamming damage (same ship shown in Fig. 17) showing damage to internals area of damage, and inadvertently they damage a vessel?s tanks. Reference (20) may have driven the vessels of this very indicates that it is not alwaYs suffi- large displacement type too hard into cient to pro”ide a cross–sectional over– the seaways. flow pipe area 1.25 times the filling pipe cross-sectional area, it sometimes A type of damage which seems to being necessary to make the ratio as consistently cam’y on, and which af- high as 1:4 to allow for constraints in flicts all types of vessels (which can the overflow pipe. be disastrous when it occurs to tanks formed by the vessel’s hull, such as is Concerning steel castings, a re– the case with bulk liquid carriers) , is markable circumstance occurred, from the the rupturing of tanks of vessels during standpoint of tim?ng, for during a four the filling of these tanks with fluids months period, approximately five years The fact that the damage occurs 80 often after delivery of the vessels, four cast would indicate that few people are aware ~tee~ IIMaPInerII rudde~ horns evidenced of how important it is to arrange tank smface fractures which required massive ventindoverflow systems to Drevent the chipping out and welding up of fractur- damage: which is invariably iaid at the es, and in some cases the renewal of the door of crew negligence. In some cases entire rudder horn casting. The disease blanks or valves have been installed in seemed to be on one side of the castings, an otherwise adequate venting system, to and was in large measure laid to the prevent overflow of oil or other contam– rising to the surface of slag and inclu- inating substance into the water sur– sions on the affected side of these large rounding the vessel. In some cases castings which were poured on their side. flame screens in vents have been painted See Figure 24. nearly shut In some cases the height of the vent head is such that from Propellers of nonferrous cast ma- static forces alone there is sufficient terials were not Without their problems, hydrostatic! pressure built up to severely particularly those of special alloys of -. L-20

-. In another area, side shell damage went marching forward, particularly for those vessels laid out in the tradition- al fashion to accommodate mooring. The results in the St. Lawrence/Great Lakes Seaway were disastrous, and caused cer- tain salt water U. S. flag operators to vow they would abandon such service for- ever. This was a direct result of the lack of rapport between the salt water and Great Lakes Segments of the U. S. merchant marine. The missing equipment on the salt water vessels was wire moor- ing winches , universal chocks, stern anchors, and the lack of tumble home and Tubbing strakes on the sides. The re- sulting side shell damage during lock transiting was enormous, as was bottom and stern gear damage from grounding aft when ancho~ed by one anchor at the bow in narrow estuaries (the docks being engaged by other vessels waiting to transit the locks) The lack of the proper ship handling equipment literally drove the salt water vessels of the day out of the Seaway, and while most of the U. S. vessels never returned to the Sea- way (certainly for many reasons) , iron- ically the Great Lakes wire mooring ar- rangement has caught on, largely stem- ming from the necessity of such equip- ~ .l.b-- ment on the larger seagoing bulk caP- riers which could not be handled PPO - perly with a multitude of fiber lines, ~ lL===- revolving gypsy heads, line stoppers, and the quantity of personnel required to operate such archaic equipment.

SAFETY, COMMUNICATIONS , AND RESEARCH

What is safety worth? Who benefits from a safe ship? Who is in a position to promote safety tbe most? J-i+””” * ““D’’”’AT” \ If everything rotates around low ‘L JOGCLED CONNECTION cost of transportation, which taken to (CFOPVED J+*G’L?SPLACSD its extremes means that each vessel will WITH )U3ECT VKL3 FI-A7E) incorporate only minimum requirements, how can damage-conscious operating per- Fig. 19. sonnel prevail? Must an owner be forced Fractures in way of joggles of tanker by monetary reasons to limit his ship web frame tie beams and bulkhead purchases to standard production items stringers, and alterations to avoid which can be produced with the minimum future failures dollar?

Taking the example of LNG vessels , alleged high strength. While a coupon current predominant fashion is to place of the original parent material may have one-fifth or one-sixth of the total shown an ultimate strength of, say, cargo in tanks of one shape or another. . 98,000 pounds per square inch, and the It is apparently left to chance to de- propeller blade thickness was determined termine whether or not the product on this basis. after failure of the should be carried in many more contain- blade in bend;ng, in service, a coupon ers. In this case design agents are taken in way of tbe failure submitted currently in no position whatever to for metallurgical examination in many sustain an argument to depart from what , instances sh;wed an ultimate strength of is accepted as conventional arrangement, approximately 40,000 pounds per square from the standpoint of added safety (and inch; clearly a case of a change in the its cost)’, versus what is saved in the physical characteristics of an alloy end through that added safety. perhaps resulting during the heating or the pour of the propeller casting from The public, shipowners, financiers, the original billet(s) See Figure 25. and underwriters-. of every .,.category all can benerit mom extra salecy arrange-

L-21 ‘“G– ience relatin~ to what might be avoided if the improvements or features were in- stalled. For example, without statis- +. tics relating to the prevalence and cost of side 6hell damage from mooring, one is in a poor position to recommend the ““”””\ installation of a bow thruster.

As another example, it Is submitted that design agents are not in a position to place more emphasis on vent arrange- ments of tanks than has been customary in the past How much information on the bursting of tanks through alleged crew negligence has been processed through design offices? The damage is prevalent, and can cost hundreds of thousands of dollars to repair.

It is submitted that the design de- ) ,4 partment of a shipyard is in a very poor +..- ! position to determine whether or not a raised forecastle should be installed on a “ULCC”, with the attendant additional cost of same, versus a flush deck ar- rangement, when there is little or no feedback from seagoing personnel, ox’ operators, condoning or condemning the flush deck arrangement on a typical ves- sel of the type.

\ Traditionally ships have not been laid out to make it easv for othe~s to LO FJG’L record damage; for exam~le, it is seldom ., ST IFF’N “R specified that frame numbers be located /\ $ on vessels. Whose fault is this? How I ‘-======many owners reauire that a casualty book be ~aintained in each ship, to avo~d /1 L wading through log hooks to find in- stances of casualties or records of same?

1(- / Some “essel operators are in a pos- ition to frequently. . add new vessels of their own design to their fleet Such fortunate operators can be guided by the faults of vessels which they built a year or so previously. Presuming good .L- in-house communications, a very high level of operating efficiency, by selec- Fig. 20. tivity, can result with such an arrange- Fractures in way of web frame ment. Such an organization is in a POs- cutouts in segregated clean ition to contribute much to research salt water ballast tanks carried out under public auspices, and importantly, is in a position to know what needs to be researched. ments, particularly with vessels carry- ing a product which has huge potential Where an owner operates with ships to damage life and property, yet there developed by others, whether they be is currently no way of placing a dollar standard designs of shipyards, or gov- - value , at the time of ship design or ernment sponsored designs, the liklihood construction. on the incorporation of of that operator contributing to research, safer arrangements in a vessel to carry via the experience of his own personnel, ; such cargoes It is unfortunate that would seem to be low, for his personnel the basis for safety always seems to be simply will not have the keenness of pur- ! regulation after the fact suit in establishing how their design can be made better, for it was “ot their 1’ In treatin= with less dramatic cas- design in the first place. ualties that pr~bably will never lead to regulation, it becomes obvious that ship Whatever the cause, where an opera- designers are in no position to develop tor? 5 personnel more or less take a back improvements, or suggest the incorpora– seat to the subject of research, research ! tion of features which cost money, where is forced into the academic theater. I they have no statistics on damage exper- . . L-- L-22 ?

1,.1 “1 Fig. 21. LaFge tankey I_oi-ecastlc head damage showing set-down of deck

Reference (21) ~i-ovides a SUmmar V When one considers the willingnes~ of sources of person;el and ship casu~l– of owners to Jump inlx a~eas ha”ing ty data, and it can be concluded from ].ittle or no Operzting history, one must that work that very little organized er,– concede that the owners ha”e shown ei– phasis has been placed on the gathering ther massi”e fortitude Ifibeifigwilling of such data. Full ship damage data re– to take what most cautious people would Quires knowledge of not only what was consider prohibit i.?erisks, or have damaged, how often it was damaged, and mov?d forward in blessed ignorance In how it was damaged, but also the cost of all but a very few instances things ha”e repairs The cost input certainly worked o“t pretty well fo~ such risk should be a nrimc catalvst to look into takers Undoubtedly reseamh in metal- various fail;res, but h;w oft,” ii re- lurgy, stru.tm’al analysis , and welding search based on such input? References has made the record possible. (22) and (23) are two of the few efforts existent in the casualty gathering SUGGESTIONS FOR THE FUTURE theater. Quite apart from the specific in- Certainly a significant part of I-e– stances mentioned earlie~ heyein of ap– search ?elates to the establishment and parent communications problems between maintenance of a system to gather damage the disciplines in”olved, there is a statistics, for without a specific indi- demonstrated current need for opera– cation of the t~ends and patterns of tional damage statistics, and the pOS– damages the leads to research aye of a sible sources of sam. Time and again, haphazard nature. When flaws or fail- to justify (or e“en establish) programs, ures are &i”en a specific dollar value, agencies and contractors (particularly research will trend more to be on a those representing d~sciplines periph- practical basis, as opposed to a theo– eral to the marine theater) demonstrate retical exercise perhaps dedicated to their need for statistics, Time consum- long-term results. ing education best desc~ibes the circum– &- L-23 Fig. 22. Large tanke~ (same ship as Fig. 21) showin~ structure inside forecastle stances as each group separately spends tributed to: the time to interview organizations Ye– ported to them as possible sources .f Shipowners and ope~ators statistics (which organizations repeat- Go”ernme”tal agencies and edly have to describe what they do or do research center-s not collect). Classification societies Design agents Obviously there should be a cent~al Shipbuilding and ship damage statistics information agency to repair yards direct such groups to. Such an agency Technical societies such undoubtedly cannot come into being nor as SNAME exist on a voluntary (gratis) basis IMCO It must be funded; either the funds must The financial fraternity come from indust~y or the government Maritime oriented schools and colleges FurtheY to the abo”e, it is suE- Underwriters gested that the recommendation set Maritime labor unions and forth in (21) be followed, i.e. , damage trade organizations data should be &enerated by those in a position to develop it, and made avail- A formal distribution of damage able to a central collecting agency, and trends and patterns among tbe above- from this data t~ends and patte~ns listed segments of the maritime industry should be distilled which should be dis– would go a long way toward creating a

. compensation foy making his vessel a,a::- able for instrumentation.

Stern gear “ibration pr’obl?,,,s , ::1- cludlng bearin,5/shaft fallmes and loss o? propel I.ers,ha”e sppeamed i.nthe I’el- e.ti”ely high speed, “cry high powered fine lined vessels of this modern age. On the othcy end of the fullness spec- trum. “ibi-ation hss Dlaxued full shi~s for years, and it wiil ;? of immense’ importance to assess its probability in the proposed low L/B, high B/H very full vessels c“rFenL1.y being considered, Re f erences (!?4)through (31) lay emphasis o“ the importance of the vibration pro- blem.

The traditional handling of pFopul– sion systems leads to fractional ization of disciplines. Many of the problems aFc of a “ibratory origin stemming from pFo– pcller–induced “ibration (hydrodynamics) and the reaction of tbe hull (structures and mechanics) Ob”iously there is a whole missing link treating totally with the hydrodynamics of the waterflow into the propeller, the propeller-induced Pul- sations, and the resnonse of the hull girder. To date, vibration analyses seem to be made by necbanically and structurally oriented people, botb of whom come j.ntothe F>icture after hydro– dynamically oriented persons ha”e fin- ished their pursuits In many cases this leads to disastrous results,

Systems must be put together to predict vibration problems with models. This may require accommodation for mo- tion in the model, s propulsion system, Fig. 23. including shafting, struts, bearings, Huge tanker, showing buckling of etc , with instrumentation to measure internal structure underdeck forward whipping or rno”cment in shafting and shaft beaFings, and possibly actual stmcture simulation in tbe models, per- rapport which, among ccFtain of the dis– haps using holographic methods as de- ciplines, is now totally missing, and scribed ir,References (32) and (33). hopefully, remedies for the ills would grow out of such distribution. In the area of wave forces the world awaits the development of a blanket, for ,More candor is needed from all model scale use, and full size use, which sides, and more cooperation. C1assifi– can be placed upon a shipvs shell that cation societies are in a unique posi– will recoi-d not onl!?Dressures . but tbe tlon to accumulate information on those envelopes of pressu;e~ from wa;e slap parts of vessels which are repetitively and slammin!3. ad”ersely affected either by the forces of nature or by people; their standards Theye is an interagency Ship Struc– will not be changed where they need ture Committee WheFe are the inter- change without a candid disclosure of agency Ship Machinery Committee and .Sbip faults. Operations Committee, the latter treating with the human error aspect of bull and Where research programs are put to- machinery pFoblems? gether and funded, which include instru- mentation of vessels, largely to provide While there may be currently some long-term benefits, and the programs re– moves to the contrary, traditionally, late to new and unusual vessels, it is would–be naval architects, when they go obvious that a part of the funding to sea, end up in the engine room. Ac- could well be dedicated to the solution cordingly, they do not personally exper- of problems that were not anticipated ience the problems of deck operation. but which when they occur require immed- They aFe in no position to treat with iate solution. In this fashion an owner the layout of cargo handling equipment, would achieve a measure of immediate moorin~ equipment , anchoring equipment ,

L-25 . Fig. 24. Cast steel “Mariner” rudder ho~n showing metal removal in way of fractures etc. Undoubtedly this was one of the CONCLUSIONS reasons why UP to the end of World War II deck personnel were toppin~ cargo 1. TheFe were inhe~ent weaknesses de– b~oms with a cargo winch and stopping Simed and built into the multi~le off topping lift wi?es with chain stop– un~ts of a relatively few types’ of pers. Perhaps this is also the Feason vessels making up the U. S. merchant why salt water vessels are e“en today rm~ine, immediately prior to and fitted with the outlandish ar~angement during World War II. foT moorin~: which i.?obtained with fiber lines, in ?ieu of wire mooring winches 2, In some areas attention was given to (34 ) The placing of expensi”e machin- the weaknesses and cures were found. ery such as an anchor windlass abow GeneTF.lly theFe was a demonstrated the deck, exposed to the weather is a lack of communications between those di~ect result of people in one d~sci– who knew of the weaknesses and/or pline either not paying attention to the v“lnerabilities , and those designing problems of another discipline, or not new vessels. giving thought as to how circumstances can be bettered. 3. CeFtain of the inherent weaknesses appeared in post World wa~ II ve8– sels of the U, S. merchant marine.

4. Ship damage history should lead to research – currently this is seldom the fact in the United States L L-26 Fig. 25. Section of p~opelle~ blade in way of f~acture

5. The development of a system for the ACKNO,WLEDCMENT gathering of vessel casualty data, definitely Including the non– The type of darage information in– theatrical but often-repeated types eluded herein is represents-;ive of the of damages, lies dormant There is dailv effort of :he United States Sal- a need for the results, and the ef– vage” Association which orgar.ization bas fort should be pursued vigorously. never failed to generously release its findings to those interested in better– 6. All pertinent disciplines should re– in~ “eSSeI operational efficiency. Ceive the I’esults of 5, and should occasionally meet to better align Special appreciation is also ex– the solution of problems as they are tended LO >1T8. Plur~el Fox who so patient– determined. lY and carefully co?mitted to paper the many wo~ds makin~, up this effo~t 7. Means to predict vibration p~oblems In the model stage must be imple– REFERENCES mented, and the need cannot be too st~ongly emphasized. 1. ,T.Vasta, Structural Tests on the Libe~ty Ship S,S. “Philip Schuyler”, 8. An interagency Ship MachineFy Com– - SNAME, 1907 mittee and Ship Operations Committee should be brought into exist ?nce. 2. M. Lotveit, C. Murer, B. Vedeler, H. Christensen, WOVe Loads on a T-2 9. Emphasis should be placed on the Tankey [dodel, Publication No. 18, necessit Y of deck de~artment service Det Norske Veritas , February, 1961 as a pari of naval architectural training. 3. Georg Vedeler, Speed and strength of LaFge Tank.?., Publication No. 21, Det Norske Verita. , May, 1961

k L--27

...-—... Q. ;eorg Vedeler, TO What Extent do 1.8. R. S. Little and S. G. Stiansen, Brittle Fr-.zctureand Fatigue Inter- Cor.reZation of Full-Scale Experi- est Shipbuilders Today?, Publication mental and Computed Stresses of No. 32, Det Norske Veritas, August, Moin supporting Structure on Large 1962 Tanke?s. Paner oresented before American Peirol~um Institute Con- 5. R. Faresi, A Simplified Approximate ference, May, 1971 Method to Calaulate Shear Force and Bending Moment in Sti Ll Water at Any 19. H. A. Schade, Interpretations of the Point of the Ship ‘s Length, Publica– !,E~So,VOFUayf,Static Test6, ~ tion of American Bureau of Shipping, SNAME> 1973 April, 1965 20. Germanischer Lloyd, Unintended Pres - 6. E. G. U. Band, Analysis of Ship Data su?e Inc~ense During Filling of Bal- to Predict Long- TervnTrends of Hull last Tcnks, 8th Shipbuilding Colloquy Be-ding Moments, Publication of Shipbuilding Industry, - und American Bureau of Shipping, Novem- -, No. 8, Vol. 23, 1971 — ber, 1966 21. Panel on Merchant Marine Casualty 7. Index of Ship Structure Committee Data, Mervhant Marine Casua Lty Data, Publications (1946 - April, 1965) Prepared under auspices of Maritime Transportation Research Board, 8. Ixdez of Ship Structure Committee National Research Council, National Rapor.ts, SSC Report No. 200, Jan- Academy of Sciences , July, 1973 uary, 1969 22. C. J. Hamrin and H. S. Townsend, 9. H. S. Townsend, Some Observations on Ship Damage, Marine Engineering/Log, the Shape of Ship Forebodes with October, 1963- appeared in Relation to Heauu Weather, N. Y. Faii-play, 28 May, 1964; The ship- Metropolitan Section Paper, SNAME, builder ~ Marine Engine-Builder, 1960 November, 19nropean Shipbuild- ~, NO. 6, 1963; and =Q 10. H. S. Townsend, A Se?ies of Cargo =, January, 1964) vessel Hull FOFWIS, T&R Symposium, SNAME, 1967 23. S. Hawkins , G. H. Levine, R. Taggart , A Limited Survey of Ship structural 11. M. K. Ochi, Pe?fozvnance of Tuo Hull Damage, SSC Report No. 220, 1971 FoFma (U and V) in IYrwgu LaP Wczues, T&R Symposium, SNAME, 1967 24. F. H. Todd, Ship null Vibration, First edition, London, Edward Arnold 12. M. K. Ochl and L. E, Motter, Predie - (Publishers) Ltd. , 1961 tioriof Slamming Chaz.acteristics and Hull Responses for Ship Design, 25. Editorial, After.body Vibrations in _ SNAME, 1973 Lnrge Ships, European Sbipbuildlng, ; No. 6, 1967 13. J. R. Henry and F. C. Bailey, SLam- rning of Ships: A Critical Revieti of 26. A. C. Viner, Ship Vibration, Lloyd’ s ~ the Current State of Xnotiledge, SSC Register of Shipping Report No. 53, Report No. 208, 1970 1968

14, J. W. Wheat on, C. H. Kane, P. T. 27. Editorial , Joint Efforts for Mini- 1 Diamant, F. C. Bailey, Analysis of mizing Engine czndP?opeller Induced Slamming Data f?mn the S.S. “Wo2ue?- Vibrations, European Shipbuildi~, j“ i.e State”, SSC Report No. 210, 1970 No, 5, 1970 I 15. P. Kaplan and T. P. Sargent, Further 28. T. Sontvedt, P~opelle?r.Induced Ezi- Studies of Computer Simulation of tation Forces, European Shipbuilding, S1.ammin,g and Other Waue-Induced Vi- No. 3, 1971 brwtory Structural Loadings on Ships in Vavee, SSC Report No. Z31, 1972 29. E. F. Noonan, Design Considezvztions ! for Shipboard Vibration, = i 16 M. Maek Earle, The what, why, Hou of Technology, SNAME, JanuarY, 1971 a Jumbo T-2> ~ Engineering/Log, [ April, 1.956 30. F. E. Reed, The Design of Ships to Avoid PropeZler-Induced Vibrations, 17 A. Haaland, Damages to Important = SNAME, 1971 Structural Parts of the 8.11, European Shipbuilding, No. 6, 1967 31. w. s. Vorus, A Method for Analy. in? the Prope LLer-Induced Vibratory Forces Acting on the Surface of a Ship stern, ~ SNAME, 1970

L-28 L 32. B. S. Hockley, Measurement of Vi- bration by Ho Zogrwphg, ~ The Institute of Marine Engineers, Vol. 84, Part 6, 1972

33. H. A. Peterson and J. P. Sikor’a, Ann Z~8is of Plastic Models of Ship Structures Using RoZogrcphy and Strain Gauges, NSRDC Report 4517, February, 1975

34. H. S. Townsend, The Case for Wire Moo?ing Winche8, Marine News, April, 1950

L-29 ?---