62 FLOATING DRY DOCKS IN THE UNITED STATES. 



While this dock is shown and referred to here as a 7,000-ton dock, with 

 eleven pontoons and a length of 368 feet, it was actually built with ten 

 pontoons and a length of 335 feet in the wings, this being the greatest 

 length v/hich would leave room for handling vessels in and out in its present 

 location on the Company's property. The additional pontoon is to be 

 added and the wings extended when the plant is enlarged. 



Referring to Plate 24, there will be seen a general drawing of a 5,000- 

 ton pontoon floating dry dock, in which both pontoons and wings are made 

 of timber. While wooden wings are not practical for the largest size of 

 docks, they are applicable to docks up to 10,000 tons. 



It will be seen from the plans that there is a bulkhead in the wings 

 corresponding to each pontoon and that the construction of the wings may 

 be interrupted at any point. In order to extend the dock, it is only neces- 

 sary to build one or more pontoons, float them in position and extend the 

 wings over them, which can be done without interrupting the use of the dock. 



The machinery and pumping of this dock is similar to the one previously 

 described. 



COMPARISON OP WOOD AND STEEL FOR FLOATING DRY DOCKS AND METHODS 

 FOR THEIR CARE AND PRESERVATION. 



As previously stated, the building of timber floating dry docks in the 

 United States is very old, and there are now in use in the Port of New 

 York sixty-four floating dry docks, all of wood, ranging in tonnage from 

 400 to 12,000 tons, and in the United States there are ninety-one floating 

 dry docks, three of steel and one with steel wings, ranging in tonnage from 

 200 tons to 18,000 tons, having a total tonnage of 228,800 tons and an 

 average tonnage of 2,500 tons. 



The only steel commercial floating dry dock is at the works of the 

 Great Lakes Shipbuilding Co., Detroit, Mich. The only other steel floating 

 dry docks in use in tlie United States are the Algiers dock opposite New 

 Orleans, La., and the steel dock taken by the United States Government 

 from Havana during the Spanish war, now in Pensacola, Fla. The Detroit 

 dock and the Algiers dock are in fresh water, which makes their preser- 

 vation much easier. 



The Tietjen & Lang Dry Dock Co., of Hoboken, has nine floating dry 

 docks, all of timber construction, varying in lifting capacity from 800 tons 

 to 10,000 tons. Their first dock was built in 1884 and is stiU in satisfactory 

 operating condition. No deterioration whatever has taken place in the 

 timber work below water, but extensive repairs from time to time have 



