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8 MARINE REVIEW. Repairs to Metal Ships. | A DESCRIPTION WITH DRAWINGS OF A LARGE JOB ON THE IRON STEAMER ONOKO--HOW WORK OF THIS KIND IS HURRIED, On account of the shallow and crowded condition of the conneciing chan- tiels « f the lakes, accidents to metal vessels are of frequent occurrence, and the 8hip builders of several lake cities, notably those of Cleveland, Detroit and Buffa'o, have «xerted themselves to a vonderful degree of economy and dis- patch in the repair work that follows. To avoid delay in dry dock, or evenan extra day or two of idleness in pors where repairs are above the water line, is one of the main objects to be attained, but the economical management of large forces of mechanics often employed on such work is also a feature of im- portance. There are, of course, small jobs that will take up almost as much time as large ones, and the location of the work also presents disadvantages at times, but as a rule the work is done with satisfaction to all concerned, and in a number of cases the thoroughness and rapidity attained in making repairs of this kind on the lakes is wonderful. In this article a description is given of repairs made some time ago on the iron steamer Onoko. The damage to the Onoko's bottom was of a kind com- . mon to lake steamers of her class. The work was done by the Cleveland Ship Buildmg Company, the boat being in dock at the yard of the Ship Owners' Dry Dock Company, which is not connected with either of the steel ship build- ing plants in Cleveland. The total: umber of men engaged on the job reached 200, the average being about 150. Upon its completion in fourteen days, the work was commended as highly economical and equal in all respects to the best work ever done in Cleveland. It will be interesting then to describe the re- pairs as they went along, keeping in mind the importance of all methods tend- ing to facilitate the work. Fig. 1 shows approximately the expansion of the bottrm plating of the Onoko, the tinted part showing the plates that were bent but not broken and the bl ck lines showing the pl:tes that were broken. Immediately after the survey the sizes of plates were taken, and the plates were ordered from the makers at once, so that no delay would occur when the workmen were ready for them. Center-marking rivets and preparing staging.--In order to avoid loss of time by drillers, it is necessary to locate and mark the large number of rivets that must be removed in such work. This is done by putting a center-punch m:rk in the center of the rivets, thus guiding the drillers and preventing the drill from glancing off. A steging must be built, as seen by Fig. A, so that the distance from the shell plate to the top of the plank will be no more than the measurement over the rachet brace and drill. On this job, fifteen men were started in the afternoon after the survey to center-mark the rivets and build staging, and on the following morning the number was increased to 135. Drilling.--This is the most important part of the work in its early stages. B, Fig. A, shows the drill penetrated into the rivet to the depth ot the counter- sink, better seen by a a and 6 6 Fig. C, bb being the plan of aa. Every effort was made to keep the rachet-braces at work continually from 7 a. m. until 5:30 p.m. There were seventy-five rachet-braces in use and they were spaced 2 feet apart, working from amidships forward and aft on B and C strakes and leaving the rivets as seen by aa Fig. C. Two boys were employed in replacing the drills when they got out of order. They carried the tools to and from the work _ Shop where they were dressed, ground, ete. Backing out rivets.--Fig. B shows the backing-out punch in place in the rivet hole a a, Fig. C, and the hammer striking it, the force of the latter driv- ing out the rivet. The rivet hole after the rivet is backed out is shown by dd, _ Fig. C, the black rim being the countersunk part of the rivet left in the hole. The men engaged in this work were in pairsand followed up the drillers about 4 feet apart. Still another small force followed up the gang who were back- ing out the rivets, and they were engaged in putting a few bolts into the rivet holes, to hold the plates in place until ready to be tak:n down. After a length of three plates was reached, shores were put under them, the bolts taken out and the shores knocked away, letting 36 feet of plating fall to the bottom of the dock. The rivets were then cut out of the butt straps left on the plates, and the plates taken out and landed on the roadway. Chippers.--The shell plates being removed, this class of mechanic was put on to cut out the bad parts of the floors, as seen by Figs. 3, 4, 5, 5, 7 and 9, and in a few days the inside of the vessel appeared as indicated by Fig. 8. Tool dressing.--Tool dressing is of considerable importance in connection with all work of this kind. The nearer the tool dressing shop is to the job, the greater the dispatch to be expected, and the Cleve and Ship Building Com- pany has accordingly located a work shop alongside the dry dock in order to secure all the advantages that may be obtained from this source. Templating floor plates.--The templaters made patterns for the new pieces of floor plates, frame angles and reverse frame angles, as seen by Figs. 10, 11, 12,13 and 15. While these pieces were being prepared at the shipyard, the lap holes were being drilled through the floor plite in the vessel, as shown in Fig. 14. The templater, before marking the template for the piece of floor plate, arranged the number of rivet holes on the floor plate with chalk, and then center-marked them with a large center punch. After the templates, Figs. D and E, were in place, a light stroke with the hammer on the pattern opposite the eenter mark left the impression of the center mark on the template; the driller being careful in drilling the hole to the mark and the templater in copy- ing the mark on the plate. The advantage of this method of drilling the holes last, was the saving of the time it would take the drillers to drill the holes, which meant a good deal, inasmuch as there were seventy-four floor plates with ninety-one butts, and as each butt contained sixteen holes, the total was 1,456 holes. Each templater made four templates, and at the ship yard laid off five pieces from each, viz., floor plate, frame angle, reverse frame angle, frame angle strap and reverse frame angle strap, in all twenty pieces. A considerable saving was effected also in lapping the floors, instead of following the usual practice of double strapping them. When the floor plates are strapped, it is necessary to chip the plates after the bad pieces are removed, so that the edge will be perfectly straight and permit of a good joint being made. When lap- ped there need be no second cut, however, as one plate overlaps the other, and in this job 136 feet of cutting was thus avoided. On account of this practice there was also a saving of 182 butt straps and 1,365 rivets, which would have been used if the pieces had been butted edge and edge insteid of being lapped. A B, Fig. 14, shows the unavoidable weakest section of the floor plate, five holes being punched to receive the rivets for the girder bar, thus weakening the floor plate 33 inches, It is not necessary to make the floor plate stronger than at this section. The floor plates were 18 inches deep. Deducting 33 inches for weakness and we have left 14} inches; then 14.25 x 3 x 22 tons=126 tons, and 126-1013, the number of rivets wanted to make the butt-lap as strong as the plate at its weakest section, A B, Fig, 14. As there were, how- ever, sixteen rivets in the lap, the riveted connection was actually thirty tons stronger than the plate through the line of rivet holes at the girder vertical angle; care being taken to have no more rivets in the outer rows of the lap than at the girder bar seen by Fig. 14. Shell plating to the éxtent of 142 feet was bent on the edge as indicated by Fig. H; 22 feet of gicder p late was also bent as seen in Fig. 2, and a num- ber of floor plates and frame angles were bent and twisted. It wou'd have been necessary to send all of this material to the ship yard to be straightened had itnot been for the use that was mide of Lucigen lights supplied by the Ship Owners Dry Dock Company. These lights were us d to heat the bent and twisted material, thus making an easy task of the work of fairing plates and angles, which might haye been cut out and sent to the ship yard to ke straightened at a great increase in cost. Only twelve of the tinted plates shown in Fig. 2 were removed and straightened at the ship yard. Templating shell plating.--As seen by Fig. 1 there were twenty-six plates broken on the shell, which had to be renewed. One templater and a boy copied twelve plates on six templates, and in the ship yard marked off plates and straps, thus preparing twenty-three pieces and only taking one trip from the dry dock to the ship yard. These templat:s were made in the ship yard be- fore hand, and one of them is shown by Fig. K. One template was put up on the end of C No. 8, and C No. 9 was copied onto it ; another template was put on the end of No. 9 and No. 10 copied onto it, the position of the plate butts being marked on both templates. No.9 was then taken down, turned over and No. 11 copied onto it, the same being done to No. 10 and so on until all the inside plates were copied on the templates, viz., C, 4, 9, 10, 11, 12, 13 and 15, A, 2,6, 7 and 9,and E5. The cutside strakes of plating were treated sim- ilarly, only the positions of the butts were lined on the inside p'ates, so that the two'templates were not puton end of each other, one being marked, turned over, and another plate copied onto it; two templaters and two boys completing the balance of the plates straps and lin:rs in one trip. The usual method of templating these plates is to mark one template, go to the ship yard, reverse it on the plate and get the plate punched, rolled and sent to the dry dock, where it is hung up in its place; then another one goes ihrough the same process, until the job is done, taking fifty-two trips instead of three, without taking the straps and liners into account. The teaming of these twenty-six plates was done in four trips, which certainly was a saving over the one plateat a time method. Riveting and caulking.--As soon as the new pieces were put together, the riveters were puton. A riveting gang consists of a holder on, a boy and two riveters. If the work is well put together the riveting part of it proceeds rap- idly. The rivets are of two kinds, hammered inside and flush on the outside. Caulking is the last stage of the work. The men engaged at caulking follow up the riveters, enough hands being put on to be done shortly after the riveters. Inventions of a Marine Nature. Specially reported from the patent office, Washington, D. C., for the MARINE REVIEW. 508,170--Thrust bearing for propeller shafts, by Moritz Immitsch of Lon- don, England ; filed Noy. 21, 1891. 508,234---Life saving grapnel, by James B. Noble and Charles G. Thomas of Southampton, England ; filed March 28, 1893. 508,260---Ice breaking apparatus, by Erich J. Weederman of Flensburg; Germany ; filed Sept. 17, 1892. 508,271--Drag for steering vessels, by Louis Boucher of West Superior, © Wis.; filed May 11, 1893. 508,324----Propeller, by Frank J. Leisen of Woodbridge, N. J.; filed Dee. 27 kao. 508,334--Propeller or fioating vessel, by Charles F. Osborne of Cape Town, Cape Colony; filed Feb 20, 1893.