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34 3 | - TAe Marine Review the machinery, the dock was declared ready for testing on June 17, 1905, just one month before the expiration of the contract time of twenty-seven months. from date of award. On June 23, the cruiser Colorado was docked, followed by the. battleship Iowa on June 27, and the preparations were at once begun for the self-docking trials. The article by Mr. Cunningham appearing in this issue, fully describes the successful docking of the Colorado and the Iowa. This article, coming as it does from the officer who. wrote the specifications under which the dock was con- CENTER PONTOON SELF-DOCKED ON END PONTOONS. structed, and who was closely connected with its prelimi- nary design, is of peculiar interest, but, as it covers only the ship-docking tests, it may not+be out of place to add a brief account of the subsequent self-docking- operations. In regard to the desired self-docking qualities of the dock, the specifications provide that it "shall be so designed and -arranged as to be readily self-docked without the aid of divers or auxiliary constructions;" that the working stress of any portion of the dock or its connections shall be limited to "15,000 Ibs. per square inch in self-docking, with a wind pressure of 30 lbs. per square foot of exposed surface;" that "when self-docked all under-water portions shall be raised to a height of not less than 5 ft., and shall be safely and readily accessible for inspection, painting and repairs;" and, that "END PONTOONS SELF-DOCKED ON CENTER PONTOON. with the dock at light-draught line, "all self-docking and strain-transmitting connections shall be above water." It may help to a clearer understanding of the operations to give, briefly, a general outline of the design in so far as it affects the self-docking features before attempting to describe the working tests. The dock is built in three sections. The center section, or pontoon, is 316 ft. in length, with side walls overhanging 80 ft. on either end. Two end pon- toons, each go ft. in length, with low independent side walls, are attached to the center pontoon in such a way that the overhanging side walls of the latter are enclosed between the independent walls of the end pontoons and rest directly on their decks when the sections are connected for docking ships. There are vertical and horizontal connections be- tween the pontoons, the vertical connéctions consisting of seven elements, each made up of forty-four 2-in. bolts; the horizontal, of four elements, one along each edge of the over- hanging side walls, each made up of ninety-six 1% in. bolts, The lower ends of the vertical connections are out of water at light draught. The self-docking is accomplished in two stages. After removing the connection bolts, the.end pontoons are hauled: clear of the overhanging walls of the center pontoon, turned so that the direction of their length is perpendicular to the axis of the. dock, and brought over the deck of the center pontoon and centered on blocking, as in the docking of ships. The center pontoon is then pumped: to the desired freeboard -- by the main pumping engines. The second stage of the operations has for its object the lifting of the center pontoon. The end pontoons are submeregd to a depth giving 12 in. clearance between the blocks and the bottom of the center pontoon at light draught, and are then drawn under either end and centered, after which they are pumped to the desired serene nee es aaa ace et gee 3 reeds estaee ay ' : ; a CENTER PONTOON SELF-DOCKED ON END PONTOONS. freeboard by means of a separate pumping plant installed in the independent side walls, to which steam is furnished by a flexible hose led fyom the forward and after boilers. On Saturday, July 15, 1005, the work of arranging the blocks of the center pontoon for receiving the two ends was finished, and all vertical connection bolts, together with half of the horizontal bolts, were removed. On Monday, cables I and 2 (see accompanying sketch) were slipped from the end pontoon bitts, starboard side, forward, and made fast by hawsers to bitts on the top of the overhanging side walls. On Tuesday, cables 3 and 4, forward, were similarly slipped and belayed on the port side-wall bitts. All horizontal con- nections wererremoved and steel drift pins placed in the bolt holes at intervals of about 25 ft. with men standing by for each pin. At 12:15 p. m. the flood valves of the forward pontoon were opened, and ten minutes later the horizontal connection diaphragms came gently apart. With the aid of a small tug boat, the end pontoon was hauled clear of the . overhanging side walls at 12:53 p. m., and made fast against the starboard side of the center pontoon at 1:35 p. m. Cables 2 and 3 were then slipped from. the tower-deck bitts and