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TAE MARINE REVIEW 33 THE ARMORED CRUISER COLORADO, ENTERING DOCK. with the dock unloaded, due to temperature changes, of sev- en-eighths of an inch were noted. The battleship Jozva was docked on June 27, 1905, for a rec- ord test, having a displacement of 11,600 tons at the time, and was carried on the dock for forty-eight hours. The speci- fications required that a 16,000-ton ship should be raised in four hours from the time the ship took the blocks until the 'keel was out of water. For the equivalent of a 16,000-ton ship the dock was pumped to a freeboard of 4% feet. From the. time the Jowa took the blocks until the keel was out of water was I hour and 37 minutes; to the time the dock had a free- board of 4% feet, 2: hours and 42 minutes. During the dock- ing of the Jowa one of the three pumping engines was out of commission for 42 minutes with a slipped eccentric, so that the actual time of operation of the dock is about half that al- lowed by the specification. 'The Iowa was docked by uniform pumiping, as in the case of the Colorado, and carried for forty-eight hours without change of water ballast in the dock. The specification re- quired that when a ship had been docked by uniform pump- ing until the dock had a freeboard of 2 feet, the deflection in the entire 500 feet of length of the dock should not exceed 3% inches. When the dock reached a freeboard of 4% feet with the Iowa, the deflection was about 2 inches. During the first 24 hours, the dock remaining uniformly pumped, the deflec- tion increased to 4 inches in the 500 feet, and during the sec- ond 24 hours showed a recovery to 33% inches. Immediately following the undocking of the Jowa the dock was pumped up to the same depth of water in the .compart- ments as when the ship was docked, which gave a freeboard of 9 feet 6 inches, and. it was found that the -dock had a. 'hog Of ft inch, During. the night this hog disappeared, and early the next morning was a half inch sag. The greatest deflection in the bearing length of the Jowa while carried on the dock was 'about 134 inches.. The deflection observations indicate that there was no permanent set caused by the docking, and that temperature. variations. may cause considerable hog or sag. After the undocking of the Colorado the main and dockide keel blocks were found to be uniformly indented. about. one- sixteenth of an inch with no crushing. No change was made in the blocks for the Jowa, and after undocking 'she was found to have rested even more easily than the Colorado. | With two feet of freeboard and.1 foot of water remaining in the pontoons the carrying capacity of the dock is 18,500 » tons, and a 20,000- ton ship could readily be docked with suf- ficient freeboard to admit of easily working' on, its bottom. The results of the docking tests with the Dewey dock show that it is considerably in excess of the contract requirements in strength, time of operation' and capacity, and is in all re- spects a very noticeable advance on all floating dry docks which have been so far projected or built. The greatest in- novation is the requirement of uniform pumping. This not otily insures safety from careless or unskilled handling, but -- makes it possible to dock nearly all ships with keel straight, or with as much hog or sag as circumstances may render de- sirable, by suitably distributing the water ballast in the dock, The ship may be also hogged or sagged while on the dock; should 'occasion arise for so doing. With 30 feet of water over 4 feet keel blocks the side walls of the dock have a free- board of 11 feet. By taking the keel blocks down to 2 feet and sinking until the side walls have a freeboard of 3 feet, 40 feet of water may be had over the blocks, so that a ship may be taken into the dock in any condition of disablement? Although a heavier ship, the deflections with the Colorada were less than with the Jowa, on account of the much longer bearing length of the Colorado's keel. With the uniform pumping the strains caused by the Jowa were much greater than will be catised by any other ship in the service, projected or built; so that the dock has had the most severe test that can be imposed on 'it. The dock was constructed under the supervision of Civil Engineer Leonard M. Cox, U. S. N,, and tested by a board of naval officers, consisting of Capt. Adolph Marix, senior 4 * ARMORED 'CRUISER COLORADO CENTERED AND READY FOR LIFTING. member; Naval Constructor J. H. Linnard, Commodore J. F. Parker, Com'dr. W. F.. Worthington, Naval Constructor J. H. Rock, Civil Engineer A. C. Cunningham and Assistant Civil Engineer J. S. Shultz. The board was assisted in the tests by Civil Engineer Cox. THE 'SELF DOCKING TESTS OF STEEL FLOATING DRY DOCK : By Civil Engineer Leonard'M. Cox, U. S. hay In the specifications forming a part of the contract between the government and the Maryland Steel Co., for the con- struction of the steel floating dry dock for Cavite, P14 kt is provided that the structure, after completion, shall be given a thorough working test before final acceptance. This test, as provided for in thé contract and its specifications, com- ' prises three distinct operations. time, to a specified freeboard, and with limited deflections of the heaviest type of cruiser; the lifting, under similarly The lifting, within a given specified conditions, of the heaviest battleship; and finally, the lifting of its own hull clear of water. On June 10, 1905, the dock was launched from the butte. ing basin at the manufacturers' works, and was immedi- ately towed to the mouth of the Patuxent river, the site selected for the official tests. After preliminary trials. of *Journal American Society of Naval Engineers