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1899.] MARINE REVIEW. 17 STEEL HOPPER DREDGES. TWO IMMENSE VESSELS OF THE BRITISH SUOTION SHA-GOING TYPE WILL BE BUILT FOR A JOB OF DREDGING IN NEW YORK HARBOR INVOLVING THE REMOVAL OF 49,000,000 TONS OF SAND--A WORK FOR WHICH CONGRESS HAS APPROPRIATED $4,000,000. New York harbor's new ship-channel will be dug by two mammoth dredges of the British suction tube type. The contract for the construc- tion of these vessels, which it is estimated will cost $500,000 each, will be awarded to a coast ship building firm in a few days. Congress has appro- priated $4,000,000 for the purpose of making the east channel 40 feet deep and 2,000 feet wide. The length covered by the proposed dredging opera- tions will be fully six miles. Government engineers estimate that it will be necessary to excavate 39,000,000 cubic yards or 49,000,000 tons to make the east channel fit the specifications. Borings have shown that the dredges will encounter nothing but sand and mud, and the contractor, Mr. Andrew Oderdonk, says that the finding of rock is highly improbable. The new dredges will be ocean steamships. They are 320 feet long, 48 feet beam and 21 feet 6 inches deep. The sand which they bring up through their 4-foot suction tube will be delivered into eight large hop- pers, located amidships. These vessels will carry over 3,000 tons of sand each in their hoppers, and they will have a pumping plant on board capable of pumping 6,000 tons of matter per hour. Making allowance for of the hopper. It is ejected in a series of jets from a set of pipes. The pipes receive their supply from the circulating pumps. Gear for control- ling the speed of the sand pumps is in a small house on the steering bridge, where there are also indicators to show the depth'of the nozzle of the main suction tube and the pressure on the hydraulic main. There is an automatic apparatus, by means of which the suction tube is balanced, so that with the ebb of the tide the end of the tube shall rise or fall as the sand is removed. The pumping engine for the hydraulic gear is'a two- cylinder compound engine with double-acting pumps. The vessels are double-enders, with a large rudder at each end, both of which may be worked by steam or hand screw gear. A crew of about forty-five men will be carried on each boat, and first-class accommoda tions for the men are located in the forecastle and poop. A large electric plant with two searchlights, steam windlass, steam winches, steam steer- ing gear, evaporator and other desirable auxiliaries will be fitted, so as to make these vessels the largest and finest ocean-going dredges in the world. NEW CAMDEN SHIP YARD. Active operations in the establishment of the new yard of the New York Ship Building Co. at Camden, N. J., began last Saturday. The tract of land, which, by the way, is valued at $176,000, was staked off and surveyed. Permits have been taken out for the construction of nine buildings and work upon them will being at once. Six of the buildings William Pife , Jun" Designer of the "Shamrock." ---------- ( Shed at Thornycrofts, Chiswick, where the"Shamrock" ete Tig dessa ; PMA Bria ib was fashioned. ~ MAMMA wd LOOM Wy ee ( » ify Va f | tli | | ee Pea ft : a t / i D a | ') | lene nh wee i i i) | Hi i J Samudla's ald yard, Millwall, where the"Shamrock" = 2 i > , \AEY/) \: was lavinched. Sir Thomas Lipton, the Owner. YAOHT SHAMROCK, WITH WHICH SILK THOMAS LIPTON HAS OHALLENGHD FOR THE AMERICA'S CUP. the speed of average working, and for the time required by the big dredges to take their loads eight miles out to sea and dump them, it will take, as a rough estimate, 750 days of twenty-tour hours each to carve out this new waterway. The vessels will be of steel, self-propelling, with twin-screw, triplé-expansion engines, capable of driving them at a speed of ten knots loaded. ; For pumping the sand there are two large centrifugal pumps, having 36-inch suction and delivery/pipe, each worked by a triple-expansion en- gine. The pumps, placed on each side of the center well, draw from a T head at the top of the suction pipe. This T head also serves as a trunion around which the tube can swing, so that it can be raised or lowered at will. Fitted to the suction tube close to the T head is a ball and socket joint; which gives a motion sideways. The nozzle of the pipe has its aperture nearly at right angles to the axis of the tube, and is so arranged that nothing of sufficient size to choke the pumps can pass through it. Each centrifugal pump may be disconnected in case of accident and the other pump may be worked alone. By means of a hydraulic apparatus, the suction tube is raised and lowered. The tube is long enough to enable the vessels to dredge in 47 feet of water. The suction tube is also fastened by chains and other gear, by which it may be lifted in case of accident to the hydraulic apparatus. : E Along two landers, one opposite the delivery of each pump, a mix- ture of sand and water drawn from the channel is discharged into the hoppers. The flow of the mixture is so regulated that the port and star- board hoppers are filled simultaneously. Each hopper has a discharging door. The aperture is closed by a valve which opens upward, and is sur- rounded by a slightly-tapering trunk, which extends upward to the top of the hopper. The sand is cleaned out of the hopper by means of water, which is supplied through the center of the discharging valves. The fluid is thrown out through a round aperture about 9 inches above the bottom are one-story structures of brick and iron construciion, and are of the following dimensions: 92 by 180 feet; 156 by 557 feet; 184 by 557 feet; 412 by 940 feet; 50 by 100 feet, and 115 by 130 feet. The three one-story wooden buildings are 60 by 200 feet; 50 by 150 feet, and 50 by 182 feet. The 940-foot building approximates the length of three ordinary blocks and will probably be the largest building in America devoted to ship building purposes. As has been previously stated in the Review, the tract of land occupied by the new company has an area of 120 acres and a frontage of 3,500 feet on the Delaware river, there being along the entire front a depth of 40 feet at low tide. The Pottstown Bridge Co.'s works at Pottstown, Pa., were purchased some time ago by persons interested in the ship building company and the material for the buildings is being worked up there. More than 7,000 tons of steel for construction has been contracted for and 3,000 tons have already been rolled and delivered at the Pottstown works. About 10,000 piles have been purchased for foun- dation work in the ship yard and delivery of a large consignment has already been made. : ; Capt. Randle, formerly of the American liner St. Louis and now gen- eral superintendent of the New York company, is more than enthusiastic over the prospects. He says that the location is ideal and that the com- pany will have within a year or two the largest ship building plant in the world. In speaking of the location Capt. Randle said: "We have one of the best sites in the world--over 40 feet of water at our launching slips, a clean bed of sand and gravel and not an atom of mud anywhere. We shall have one of the largest dry docks in the world, 860 feet in length, although whether of stone or wood is not yet settled." It is anticipated that more than 1,000 men will be at work at Camden within a few weeks, and the yard when in operation will undertake to build ships of every description.