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THE MARINE RECORD. 7 CRIB WORK FOR PIERS AND BREAKWATERS. % “AS DESIGNED BY COL. JARED A. SMITH. A large section of the cribwork for the new east pier ‘for Cleveland harbor was launched Tuesday by Mr. _ James Donnelly, of Buffalo, who has the contract for rebuilding that structure. The manner of construction is comparatively new, and embraces features of such radical improvement in former methods, in the items of ‘stability, cost, and rapidity of construction, that a clear explanation of the system, which has been touched “upon before in these columns, will be of practical bene- wise have to be thrown out, because of waning edges. For obvious reasons, there is'\no bottom built for this crib, with the exception of a compartment here and there, in which a bottom is put in order that the ballast may be thrown in and the trim of the section maintain- ed after it is in the water and sides and cross-walls have been built up. It must, of course, be understood that because of the great weight of such a section, it must be built up, before launching, only so far as is absolutely necessary to maintain its rigidity of form, and to ensure the character of the work to be perform- SEVERAL CRIBS, JOINED WHILE AFLOAT—BUILDING UP PROCESS BEGUN. fit to many, and of interest to all. The illustrations here presented show some of the crib of the new pier work built at Conneaut harbor, on the same plan, with one exception. The first illustra- tion shows a section of the crib work, about 30 feet in length, or about as large as is convenient for launching. The end of the section is shown in the foreground. For the Conneaut pier the cribs were set on a-rock bot- tom, which had been dredged out a few inches before the cribs were placed in position. On such a founda- tion undermining by water was out of the question. But in the crib work for the Cleveland piers the first row of cross-timbers from the ground project about 6 feet on each side of the crib proper. This leaves 6 to 8 inches of the crib, below those cross-timbers, to sink into the sand foundation; but upon these projections is laid planking, which forms an apron. The usual course of the volume of water thrown up by the sea striking a pier, is to drop vertically along the line of its ascent. In this way it falls with such force as to scoop out a trough if the bottom be of sand or soft mud, and eventually the crib is undermined. This apron is made to receive the impact of these falling volumes of water, -and the undermining is thus prevented With this one exception the method of construction is precisely as at Conneaut. The aprons have already been used with great success at Fairport. The great advantage in the work of construction lies in the absence of dovetailing, which is disapproved for other reasons than expense of building. Col. Smith’s annual report for 1895 states that some old crib work which had been taken out of the water was fourd to be worthless, owing to the tearing away of the dove- tail heads of cross-ties and cross-walls, as well as the ends of timbers framed together at angles and cribs. The water for many years, loaded with mud and sand, had been forced back and forth around these dovetails until they were so worn that the clear space was often as great as two inches, where the timbers should fit very closely to give the requisite strength or stiffness. It was due to the decking which held to the tops of the walls in places, and the fact that the stone inside had become cemented together with hard mud, so that there was no outward pressure, that the cribs had not long before fallen in pieces. The first illustration shows the section, with four courses of timber on the sides, and two on the cross- walls, with six-inch pieces placed between and gains cut for the reception of the longitudinal strengthening timbers. Five cross-walls are shown, and these will be built up solid to the top, as will the side-walls. Thus tour separate apartments are formed, in each corner of which upright square timbers are tightly fitted. Tio these both the cross and longitudinal timbers are tightly bolted. This is what cheapens and strengthens the work, as it is a more than efficient substitute for dove- tailing, and allows the use of timbers that would other- into water. ‘launching till they are placed precisely end to end, and ed while the sections are afloat. ‘The first illustration, therefore, shows the section ready for launching. In the second engraving, several of these sections have been built and floated, and another is ready to go These sections are towed around after then begins the putting on of the timbers of the side walls. These, of course, lap over the ends of the sec- tion, where the first three courses of the side walls butt, and the section is thus made solid. .The cross walls and side walls are then carried up to the requisite height, the structure sinking in the water and being main- .tained in its upright position by means of ballast thrown in upon those compartments which have been fitted with floors. The height, or depth, of the cribs is not limited by the height of the corner pieces as shown in the first two illustrations, as they are, it will be no- ticed, of irregular length, so that the splicing of them occurs irregularly and the crib is thus not weakened at any particular depth. It must also be noticed that long iron rods 1% inches in diameter pass through the crib from side to side, at frequent intervals to receive the outward thrust. Wherever longitudinal timbers butt, the rod is provided with an immense washer of iron, to hold the ends of both timbers: The corner timbers are fastened to side and cross walls by means of screw -bolts.. The arrangement is such that the bolts draw the timbers very close together and make the crib be noticed that the alternate compartments are tempor- arily decked over. Before towing the crib out to its final resting place, it is necessary to have accumulated plenty of the stone ballast, and to have it on hand at the site of the proposed pier. The crib is then towed to the desired position, and a quantity of the ballast is thrown upon the temporary decks until the structure rests lightly on the bottom. By hauling on lines, bunt- ing with a tug, and other means at hand, the crib is then easily brought into the exact line desired, so that the structure when completed shall be entirely plun.b, and perfectly straight to the eye in a longitudinal direction. This being completed, the open compart- ments are partially filled with stone from the vessels, and then the ballast at first placed on the decks is thrown in, Itis obvious, of course, that the ballast at first placed on the decks must not be thrown into the compartments at first, as the stone would weigh less in the water than on top of it, and the structure would float out of place; and it would be equally fruitless to throw the ballast into the bottomless compartments until the grillage was finally rested on the bottom. After the open compartments have been filled, the temporary decking is removed, and the intermediate compartments are filled with the ballast. The grillage is then ready for the superstructure. In the Cleveland east pier, now building, this superstructure will be of concrete. This will be made in blocks 9 feet long by 4 feet wide, and 3 feet thick. The crib work will come to 3 feet below the water level, and the concrete blocks will be laid upon this. It will thus require one tier of concrete blocks to bring the structure up to the surface. On the top of the concrete pier the blocks will contain, at short intervals along the edges, large iron mooring wigs, attached to rods which shall have been imbedded in the blocks when in process of moulding. This will be of great benefit to vessels tying up there. The west pier and the breakwater, when constructed, will all be built up on the same general plan, with the slight modifications necessary to meet the objects of the work. It will be seen that this system admits of very rapid work, and removes almost entirely the necessity of working with divers. The finished part, then, will, in a few years present a most handsome appearance, in- stead of the dilapidated showing now made. EEE —eE WILL STAY TILL NEXT WINTER. The tour of duty of Commander Charles D. Sigsbee, the Chief Hydrographer of the Navy, expired on May 31 last, but as there was no commander’s billet vacant he has been retained on duty at the Navy Department. It is expected that he will remain in his present station until the winter, when it is probable that a sea com- mand will become vacant to which he may be assigned. To Commander Sigsbee is due the recent great progress in hydrographic work. He has been an ardent advocate of the proposition to place the coast’ survey under the Navy Department and to make acombined Hydro- SECTION OF CRIB, READY FOR BALLASTING AND SINKING. vastly more rigid and strong than is possible with the old method of dove-tailing. The third illustration shows the crib work practically completed. It has been built to a depth of say 18 or 20 feet, or about the depth of water where it is to be placed. It has been built in sheltered waters, and this is another advantage over some old forms of building, where the construction is of necessity from: the shore outward, and where new work is sometimes destroyed by heavy weather before it can be completed. It will graphic Office, which should be raised to the dignity of a bureau. His failure has been due to inaction by Congress, the Navy Department having earnestly rec- ommended the plan which Commander Sigsbee favored. Considerable speculation is overheard as to his successor. — re The Iron Age has left its old editorial rooms, Nos. 96-102 Reade street, and has removed to new and larger quarters at Nos. 232-238 William street, nearer its me- chanical department. :