FLOATING DRY DOCKS IN THE UNITED STATES. 6i 



the side planking 5-inch and the end planking 6-inch. 6"X 8" deck timbers 

 are worked across the 10" X 10" truss members on top and bottom in such 

 a way that it is possible to get in the i|-inch double tie-rods without boring, 

 and so arranged that they can be replaced at any time. 



The material is merchantable grade of yellow pine lumber throughout 

 and the fastenings are all galvanized. There were required for each of these 

 pontoons 135,000 board feet of lumber. 



The steel wings of this dock are 368 feet long by 30 feet high, 12 feet 

 wide at the bottom, and 8 feet wide at the top. The detailed construction 

 and bracing are shown in Plate 22. The plating varies in thickness from 

 one-quarter inch to one-half inch. Referring to Plate 23, the manner of 

 securing the wings to the pontoons will be seen. This is accomplished 

 by means of a cast-steel shoe secured to the deck of the pontoon and con- 

 nected by a link and taper wedge and similar shoe riveted to the side of 

 the wing. On the outside of the dock, attachment to the pontoon is by a 

 cast-steel strap through-bolted to the side of the pontoon. This device is 

 of exceedingly simple construction and has proved most effective. 



A pontoon has been detached by knocking out the wedges in less than 

 ten minutes. The remainder of the dock is then pumped up, when the 

 detached pontoons can be floated out and dry-docked on the remain- 

 ing pontoons. The total weight of steel work in the wings is 1,100 tons. 

 Attention is called to the fact that all of this steel is normally above the 

 water-line, where it is accessible at all times for examination and repair. 



Contact between the wings and pontoons is made by a raised packing 

 piece, 12 inches wide, surrounding the open top of the pontoons under the 

 wings, it being understood that there is a hole in the bottom of the wing 

 to allow free passage of water from the pontoon to the wing when the 

 pontoon is full. The joint between the pontoon and wing is made with 

 three-ply canvas packing, saturated with red lead, and the wing, at the 

 point of contact, is reinforced with f"Xi2" steel plate to insure against 

 possible corrosion, this being the only part of the- wing, inside or out, which 

 is not accessible when the dock is in commission. 



By referring to Plate 20, showing a general plan of the dock, the method 

 of pumping will be understood. This is by a centrifugal pump in each end 

 of each pontoon, all the pumps on one side being operated by a single 

 electric motor through horizontal line shaft and vertical shaft to the pump. 

 The delivery and entrance of water to the pontoon is through the pump, 

 which has been found to be a very effective method of control. A more 

 complete description of the construction and operation of this dock can be 

 found in "International Marine Engineering" under date of August, 1909. 



