METHOD OF CONSTRUCTION OF CONCRETE SHIPS. 23 



important part of the outfitting. Besides the main engine and boilers, it includes all 

 the auxiliaries such as pumps, condensers, stearing gear, refrigerating machinery, 

 generators, capstans, windlass, and cargo winches. 



In the 7,SOO D. W. T. ships, both cargo and tankers, the propelling equipment 

 is the same. The engine is triple-expansion, three-cylinder, vertical inverted direct- 

 acting Stephenson link type, with cylinders 243^2 inches, 415^ inches, and 72 inches 

 in diameter with a 48-inch stroke, and is to develop 2,800 horse-power at 88 revo- 

 lutions per minute (corresponding to a cross-head speed of 700 feet per minute). It 

 is to operate at this speed with 200 pounds steam pressure. Steam for this engine 

 is generated in a battery of three oil-burning Foster water-tube boilers, which are 

 located in a boiler-room just forward of the engine-room. Each has an external 

 heating surface of 3,050 square feet, and is to be built for a working pressure of - 

 225 pounds per square inch. 



Both engine and boilers and all the rest of the outfitting equipment are prac- 

 tically the same as those used on a steel ship of the same size. The only points of 

 difference are in the details used to fasten the various pieces of equipment to the 

 hull. The heavier machinery and the boilers are supported on steel grillage, which 

 is fastened to the frames by means of. bolts set in the concrete. 



At Jacksonville the steel grillage was omitted under the engine, and a concrete 

 foundation was provided to which the engine bed was directly secured by bolts pass- 

 ing through pipe sleeves cast into the concrete. 



The location of these inserts is determined, by means of templets on which 

 the bolt holes are spotted either from the machinery drawings, or, better still, from 

 the base of the machinery itself. For some of the other lighter members such as 

 ladders, etc., the pipe sleeves are sometimes omitted, and a bolt with a large washer 

 is placed directly in the concrete. The deck machinery subject to much vibration, 

 such as cargo winches, windlass and capstan, is set on 2-inch oak bolsters. In the 

 case of some of the smaller equipment, such as mooring bitts, the part is placed in 

 position on the forms before concrete is poured. 



It has been found difficult to place the smaller bolts and inserts so that they 

 would fit the equipment unless they are set with templets taken directly from the 

 casting. The drilling of ship castings and fittings is usually not exact according to 

 drawings. Very little difficulty has been caused on this score, however, for if a 

 bolt does not line up with the hole in the fitting a new hole is easily drilled in the 

 concrete and a new bolt grouted in place. 



The cargo-handling equipment of the 7,500-ton cargo ships is similar to that 

 on a steel ship of the same size. There are two masts (see Fig. 3, Plate 7), each 

 with four 5-ton cargo booms and each serving two hatches. In addition, one 30-ton 

 boom can be rigged to the forward mast if necessary. When this is used it is neces- 

 sary to shore the decks under the boom and to install additional guys, as the regu- 

 lar shrouds will not carry the load. 



On the tankers no such elaborate equipment is necessary. Here most of the 

 cargo is handled by pumps located in special pump-rooms adjacent to the main 



