PRESENT STATUS OF THE CONCRETE SHIP. 

 Bv R. J. Wig, Esq., Visitor. 



[Read at the twenty-sixth general meeting of the Society of Naval Architects and Marine Engineers, held in 



Philadelphia, November 14 and IS, 1918.] 



There is much interest throughout the world in the development of the concrete 

 ship. Ships of concrete are at the present time being built in England, France, 

 Spain, Italy, Germany, Norway, Turkey, China and the United States, but so far 

 as we are informed, there are no concrete ships under construction outside of the 

 United States larger than 3,000 tons deadweight. The United States Government 

 now has under contract 56 concrete ships, varying in size from a few hundred tons 

 to 7,500 tons deadweight, aggregating 300,000 tons total deadweight, in addition to 

 some 34 barges and lighters, and the future position of the concrete ship should be 

 established by the results obtained from these ships which are now under contract 

 and building. 



The use of reinforced concrete for ship construction has been suggested by the 

 structural engineer and not by the naval architect. Like all innovations its develop- 

 ment has been observed by some with much skepticism. The structural engineer has 

 worked under a great handicap in not knowing the premises of ship design, and dur- 

 ing these very busy days of the past two years it has been difficult to obtain the as- 

 sistance of naval architects who could join the structural engineer in adopting this 

 new material to ship structures. 



It is a misnomer to call the concrete ship a "stone" ship. It is essentially a steel 

 ship in which the proper quantities of steel are located where strength is necessary 

 and concrete is used as an envelope and cementing medium with certain contributing 

 strength. 



Unfortunately the structural design of ships in general has not been developed 

 on theoretical grounds, but rather from empirical standards and experience. Rein- 

 forced concrete is such a radically different material from steel and has such dis- 

 similar physical properties that it hcs been necessary to devote much time to theo- 

 retical analysis of the ship structures which is not undertaken at all in steel ship 

 design. 



Reinforced concrete is a structural material which is capable of carrying any 

 structural strains which can be carried by steel alone; therefore, in order to make 

 a concrete ship equal structurally to a steel ship, it is but necessary to make careful 

 analysis of the steel ship both as a whole and in its individual elements, to provide 

 the required quantities of steel as reinforcement in the concrete where tensile strains 

 are involved, and provide the concrete to care for the compression and shear strains 



