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126 THE MARINE REVIEW forcing, making a continuous bond with the decks, ribs, bulkheads and beams. The concrete is placed by the best method possible for strength and density. It is proposed in future con- struction that concrete ships shall be built, including all the housing, staterooms, and even to the decora- tions, in one true monolythic bond. Both the. American Register and Lloyd’s will give A-1l rating to con- crete ships constructed from approved plans and specifications. Construction done- for the Emer- gency Fleet corporation includes many specifications which some shipping ex- perts contend are over-cautious. In ordinary reinforced concrete, 1 per cent or 2 per cent of steel rein- forcement in a concrete beam in a building is thought excessive. The shipping board has been experimenting with 5 per cent, 6 per cent and 7 per cent of reinforcement, in order to develop the shearing stresses which their experts consider necessary in order to get a ship that is a com- mercial proposition. Steel arranged both diagonally and vertically has been used. Diagonal steel was used in the Farru. Steel so placed is stressed not only because of the diag- onal tension present, but is also stressed by the longitudinal movements. When the steel is placed vertically, any stresses due to longitudinal bending point are. eliminated. Experts are not agreed which is the better method. Ample Safety Factor The steamer FaitH is said to con- tain more reinforcing than is necessary, and an even greater amount was put in the Attantus. Some experts de- clare that from 5 to 6 times more rein- forcing steel than was necessary was put into these two ships. But it was acknowledged that the Emergency Fleet corporation adopted a safety factor of 4 in the construction of its ships be- cause it was not desired to run the least risk. The extra reinforcing in the - ATLANTUS was placed on the decks and around hatch combings. More _ steel was also distributed throughout the ship. There is about 3 inch thickness to the concrete between the reinforcing and the outside skin. The Farrn has a dead- weight of 5000 tons and a gross of 2650 tons. The ArLantus has a dead- weight of 3500 tons, and her carrying capacity in proportion to her measure- ment is undoubtedly less than that of the FairH. In _ proportion to steel ships, however, it is declared, the speed of the concrete boat is greater for equal engine power because the friction in the water is less. Experiments carried forward in America are solely responsible for this enviable position accorded the special concrete ship design developed here. Great Britain, it is true, is building now some 200 vessels of concrete, and France about 400 of the same ma- terial. Spain has already put into service one 6000-ton concrete ship and plans to build a total of 2,000,- 000 tons of shipping of this material. Italy has a concrete shipbuilding pro- gram under consideration of equal magnitude to that of Spain. And inquiries from Japan, New Zealand, and Australia indicate that the new method of building ships is rapidly spreading around the world. Forms Present Some Troubles In pouring the cement on_ the frames or reinforcing many improve- ments have been projected. Approxi- mately 85 per cent of the trouble encountered in building vessels of concrete, it has been said, is due to forms. The concrete experts, there- fore, are striving to work out a method whereby the vessels can be built without forms. The reinforcing is fabricated and a metal lath is used for the purpose of a form. The cement is then to be placed by use of the cement gun. In this method of construction it would be necessary to have an outside skin of less than 2 inches. In anather case the frames are precast and set into position and the concrete hull built around. Ce- ment barges have been successfully built by this latter method. The ex- perts insist that. it is not necessary that the continuous method of placing the concrete be adopted. One of the best methods of placing the con- crete, both physically and econom- ically, it is said, is that where the concrete is driven by compressed air in batches from the mixture to the destination. Just at the point of dis- charge the pressure is released by air valves or vents, giving any re- quired pressure at the end of the nozzle. When concrete is delivered by the old method in the barrow, the mixture has a moment to settle and it is not delivered at its destination in its freshly mixed condition. The improvements made along these lines are the things which have . done much to convince many shipping peo- ple that concrete shipbuilding is a practical thing. Improvements may be made in other directions, and the dream of a successful stone boat may yet have a practical realization. To give the concrete boat its just consideration, it must be acknow!- edged that concrete shipbuilding in the United States is a new industry. During March, 1918, the Universal Shipbuilding Co., Sturgeon Bay, Wis.., took contracts to build 12 reinforced concrete barges. During May of the March, 1919 same year J. L. Weller, Tonawanda, N: Y= took: a:-contract for 30: tow barges. The Concrete Steel. Ship- building Co., Savannah, Ga., under- took to build a concrete freighter; the S:.° S:=Saxton: Co., Chicago, pro- jected work on five concrete tankers, and the Torcrete Shipbuilding Co., New Orleans, proposed to build oil barges of concrete. The Delta Ship- building Co., New Orleans, was at work on several river barges. It was last August when the ship- ping board became definitely inter- ested in concrete shipbuilding and decided to take over the which had been constructed on private account at San Francisco. Then the Emergency Fleet corporation entered upon its program to construct five agency yards in which large concrete freight boats are to be- built. The agents for these yards are the Lib- erty Shipbuilding Co., Brunswick, Ga., and Wilmington, N. C.; A. Bentley & Sons, Jacksonville, Fla.; Fred T. Ley & Co., Mobile, Ala.;. Scofield Engineering Co., San Diego, Cal., and the San Francisco Shipbuilding Co., San Francisco. Awards Many Contracts The war department also entered the field and obtained bids and awarded many contracts for concrete barges. for the embarkation service. Among the awards made were con- tracts let to the Liberty Shipbuilding & Transportation Co. Cleveland; West Coast Shipbuilding Co., Everett, Wash.; Great Northern Shipbuilding Co., Portland, Oreg.; Samuel Beskin, Peekskill, N. Y.; Ambursen Construc- tion Co., Pagoda, N. J., and Louis L. Brown, Inc., Verplank, N. Y. Many persons went into the concrete boat. building business and an ever in- creasing interest has been shown in the industry. The Houston Bank & Trust Co., Houston, Tex., has had drawn up plans for two 2000-ton passenger ships which are intended to ply between Houston and Phila- delphia. A list of the persons and companies building watercraft of reinforced con- crete today would be extensive. The number of bankers and naval archi- tects, engineers, and other experts who have shown interest in the baby industry is tangible proof of the faith of influential men in the future out- look. No one is prepared to con- tend that a powered concrete vessel of today’s construction equals or ex- ceeds in utility a steel vessel of mod- ern design. It is the fact that the field of developments in concrete shipbuilding is so large and so prom- ising that prompts these people to pin their faith to it. FairH . a 7 J . : a ; ‘ : a hel ‘