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1901.] MARINE REVIEW. 15 LARGE BALANCED SECTIONAL DRY DOCK. William T. Donnelly, who was in charge of the construction ol a sectional floating dry dock of 10,000 tons lifting capacity at the dock yard of Messrs. Tietjen & Lang, New York, described the work in a recent number of the Engineering News. The dock is capable of handling vessels of 500 ft. length. Mr. Donnelly's description is as follows: The Lang balanced sectional dry dock is composed of five sections, each 110 ft. 10 in. wide, and 80 ft. long. When coupled together they are separated by 20 in. and the section at each end has an overhang of 30 ft., making an over all length of 466 ft. 6 in. The depth at the center is 13 ft. 6 in., and at the waterways 12 ft. 6 in. The height of the wings is 39 ft. 9 in. The draught of the dock, light, is approximately 4 ft. 6 in., the maximum draught which can be lifted 26 ft. and the maximum lifting power 10,000 tons. The available width between wings is 92 ft. The pumping machinery consists of duplicate sets on opposite sides of the dock, each composed of two 125 H.P. vertical boilers, operating engines with cylinders 20 in. diameter and 24 in, stroke, and making 150 revolutions per minute. Each engine drives a line shaft, which runs the entire length of the dock. These operate six pumps on each side of each section, or a total of sixty pumps. The pumps are 16 in. square by 20 in. stroke, and as they are driven by a reduction gear of one to two from the engine shaft, they make seventy-five strokes per minute. This machinery is designed to pump the full capacity of the dock in 45 minutes. The sections are coupled together by what are known as lock- ing logs, which connect the sections together through keepers. These logs are of oak, 40 ft. long and 24 by 28 in. in section. The essential principle embodied in the Lang balanced sectional dry dock and that which has made a floating dock of this size possible, is the manner in which the sections are divided into water tight compartments. The separate sections in the previous sectional dry docks were without transverse bulkheads, and any inclination of a section in a longitudinal direction. would cause the water to flow towards the lower end and increase the difficulty of the unbalanced condition. In the Lang dock this has been overcome by building two transverse bulkheads in each section and providing independent means for pumping each compart- ment. This results in giving to the sectional dry dock the desirable features of the present balanced dock, and at the same time retaining many desirable features of the sectional dock. The choice of machinery for this class of dry dock involved the con- sideration of a great many questions, and results were only arrived at by a series of eliminations. We were fortunate in this instance in having the guidance of all that had been done in and about these waters, and the requirements or conditions that the machinery must meet have been pretty well threshed out. Simplicity and reliability are of the first im- portance, and economy or efficiency which more often heads the list in large engineering work, is here the last thing to be considered. When it is understood that the machinery at the most will be used but one or two hours in the twenty-four, and more often only once in several days, the small importance of steam economy is apparent. Therefore, in selecting the type of engine, we chose the simple, direct-acting, vertical engine of ample power and of great strength and solidity. The boiler question was limited to such types as could be handled in the extremely limited room on the top of each wing, and the upright type with vertical tubes and submerged steam dome was considered to meet the conditions most satisfactorily. The question of pumps is one that is very broad, and after going over the ground carefully, we became thoroughly. con- vinced that that type of pump which has quite generally been used on these docks, and which the Tietjen & Lang Co. used on all of their. other docks, possesses qualities of simplicity and durability that cannot be ex- celled by more modern and perhaps more mechanical appliances. This pump is a square wooden box made of 4 in. oak planking, 16 in. square inside, and about 14 ft. long, or reaching from the bottom of the dock up through the floor of the pump-well a short distance above the deck. There are two of these pumps for every transverse compartment of the dock. They are single acting and each is' provided with a foot valve near the bottom of the pump barrel. The foot valve and plunger are made from the same pattern, and are practically gridiron valves, with a rubber diaphragm. The foot valves drop into a taper seat near the bottom of the pump barrel, and the plunger is attached to the lower end of the pump rod. The packing of the plunger is of 4 in. leather belting secured at its lower edge by rivets and free at its upper edge to press against the pump barrel. These pumps have been found to have exceedingly long life, and the parts to be replaced in case of wear or breakage are very simple and inexpensive. The pump rods are connected to a rocker arm, and on one end of this rocker arm is attached a con- necting rod operated by a crank on the end of a shaft driven from the main line shaft. The pump rods are of 4 in. I-beam, and the connecting rods of 5 in, I-beam. The boxes at the upper end of the pump rod and each end of the connecting rod are of bronze and are duplicates. The crank shaft and line shaft at the point where the reduction of speed is ef- fected are carried in two stands, and the bearings for both line shaft and countershaft are made from the same pattern, and by means of these stands the distances between centers of the gear are accurately main- tained. The object of referring to these details is to show the effort which was made to effect the greatest possible duplication of parts. In proportioning the machinery for the work to be done a large factor of safety was used, as a break in any of the machinery during the lifting of a vessel might involve a loss of much time, an item of the greatest value in the case of large vessels. The great duplication of parts makes it pos- sible to effect any repairs quickly and with very few parts on hand. A special problem was involved in the transmission of power from one section to another. When it is understood that a section may have a relative movement only limited by the locking log, and that this move- ment may be in any direction, it will be apparent that the connection must be both a universal joint and a slip coupling; a universal joint, so that the shaft may turn when out of alignment, and a slip joint so that the sections at this point may come together and separate without inter- fering with the transmission of power. As the slip coupling must oper- ate under the strains of power transmission, it is necessary to provide a thrust bearing to each section. This was accomplished by securing a flanged hub to the shaft and bolting securely to the top of the dock a cast-iron plate or shoe which engages the flange of the hub and prevents longitudinal movement of the shaft. The slip joint was made of a square shaft, and all the parts of this joint and the universal joint are of cast steel. The flood gates of the dock have an opening 12 in. square, and the closing slide is made with a taper at each side of the back, so that when forced down by a rod it will be wedged tightly against its seat. The operating rod runs up through the side of the wing, and the gate is raised and lowered by a wheel operating a bronze nut on the upper end of the gate rod. In operating the dock, the engine and all the pumps are running all the time, and the desired lift to correspond to the weight of a vessel over any compartment of the dock is obtained by a greater or less closing of the floodgate corresponding to that compartment In this class of docks (wing docks) the wings or sides have to be built high to admit of deep-draught vessels over the keel blocks, and to carry the large and heavy machinery used in pumping. Also sufficient displacement or bulk must be given to them to insure the stability of the dock and vessel. To overcome the buoyancy of the dock it is necessary to load it with stone ballast, which is placed in the wings, amounting to 5 tons per- running foot, or 400 tons per section in the dock now under consideration. With these points in mind it may be seen that, starting with the dock down and a vessel over the keel blocks ready for docking, the sequence of conditions is about as follows: First, the interior and exterior levels of the water are about the same, as just enough ballast has been added to sink the dock to this level, and the dock is practically free from strains; second, the flood gates are closed and the pumps lower the interior level of the water, and the vessel is raised to a degree corresponding to the amount of water pumped out, but as the area of the wing is small relatively to the midship area of a vessel corresponding to the maximum lift of the dock, the drop of the interior level of the water will be much more rapid than the rise of the vessel and dock out of the water, and the difference will continue to increase until the wings are pumped out down to the level of the body of the dock, when it will be about 16 ft., which will correspond to a buoyancy or lifting power of 6 tons per running foot of the dock for each wing, or 18 tons for each wing per truss. The condition of the loaded truss would now be 36 tons concentrated load at the center and a counter strain of 18 tons at points about 7 ft. from each end. With the proportions of truss here used, this would give a maximum strain at the center of the lower chord of 72 tons. From this condition there will be a rapid change, as the lowering of the water in the interior of the dock will be over its entire area, and as this is much greater than the area of the water line of the ship, espec- ially as the immersed body of the ship decreases rapidly per foot of elevation, the difference of the interior and exterior levels of the water will rapidly grow less, the ship and dock rising much faster than the level of the interior water is lowered. This change will continue until the dock is entirely pumped out, when, if the lift has been to the maximum capacity, the dock will be just clear of the water, and the load upon it will correspond to the amount of displacement pumped out be- tween the interior and exterior levels of the water at this time, less that necessary to float the dock at this level. AN OCEAN SERVICE DE LUXE! The London Express prints a story that is at least interesting. no matter what may be said of it otherwise, regarding two great ships which Mr. Morgan has planned for the ocean ferry. They are to excel anything that has ever been seen on the water and will be to sea travel what the "limited train" is to the American railway. According to the Express story, an official of a leading American line who has been in consultation with Mr. Morgan at Aix-les-Bains says that he was allowed to see the plans for the two liners de luxe, which are to be constructed for the comfort of that. class which does not have to consider money when luxurious living is concerned. In the first place, these boats, both of which will be five-day vessels, will carry none but first-class passengers. There will be no single cabins, but suites of apartments, consisting of parlor, bedroom, and tiled bathroom. There will be suites with more "rooms, but the majority will have three. The suites will be furnished in the richest fashion and variously decorated. There will be color schemes to suit all fancies, and many styles of furniture will be represented. The passageways will be broad and well lighted. : The public rooms will be magnificent creations, decorated by famous artists. The dining room will have no long general tables, the arrange- ment being one of small tables, similar to that of the restaurant of the Hotel Ritz in Paris. Ingenious devices will be used to prevent upsets in stormy weather, and each table will have two attendants. A pleasant feature will be a grill room. A dairy will be maintained on board, ship quarters being provided, in the space usually devoted to steerage, for a small herd of Jerseys. Along with the cows there will be carried a num- ber of hens. Thus the millionaire can have fresh milk and new laid eggs though 1,000 miles from land. The arrangements for providing and keep- ing food are perfection. The greatest novelty will be a cafe chantant, where an excellent entertainment will be given each evening, the inten- tion being to engage high class artists. A theater supper will be served after the performance. There will be a gymnasium, a large library, a sun room, a full stocked conservatory to provide fresh flowers daily, a skilled medical staff, readers, stenographers, manicures. masseurs and special rooms for dogs. The cheapest passage will be £200. A cablegram Wednesday to Charles Counselman of Chicago, who has built four steel steamers for a trial of through service between Chicago and European ports, announced the arrival at Hamburg of the first of the four vessels that passed down the St. Lawrence canals on the opening of lake navigation. The passage was one of thirty-five days, of which nineteen had been occupied traversing the great lakes and canals before leaving Quebec for the ocean voyage. The Northman, which is a steamer of 1,496 tons net, sailed from Chicago April 30 in command of Capt. Ross, with a general cargo. It sailed from Montreal May 17 and Quebec two days later, and on May 22 it sailed from Sydney, C. B., after coaling. The scheme of going through the canals was to give the vessel the maximum cargo to Buffalo, there partially unload, and then after passing through the canals, reload at Montreal. The round trip is ex- pected to take sixty days.