Page:Popular Science Monthly Volume 91.djvu/573

 Popular Science Monthly

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��the use of artificial stone opens up a new avenue to the increased production of ships. Even with plans drawn, however, the actual building of such a large concrete vessel and its practicability- after it is built, are entirely different matters. ■ While every one knows of concrete's adapt- ability to almost any .form because it is handled in a plastic or semi-fluid state; of its fire- proofness; of its general use in large office buildings, in private residences, in bridges, docks, sidewalks and in practically all branches of con- struction, there is yet much to be done by naval arch- itects and marine engineers before the five-thousand-ton concrete sea-going vessel is a practical, commercial certainty. This does not mean that such a ship is an im- possibility but that American ingenuity

���orn for wat ballast or fuel oil

��A Typical Concrete Cargo Boat

It has two decks, a double bottom for ballast or fuel, and a double hull between the lower deck and the double bottom. This gives greater strength. The well known principles of concrete building construction are indicated in the form of the hull members and the method of distribution of the steel re-enforcing

���How the Concrete Hull Will Be Made

��Imagine this man standing on the scaffolding alongside a ship, and you will get an idea of how the three layers, of the hull are shot into place by compressed air. The man shown here is building up a some- what similar concrete slab on metal lathing to form the outer wall of a sewerage disposal plant. The cement is shot through a hose

��and enterprise must be brought to bear and problems peculiar to concrete con- struction solved.

The Concrete Vessel Is Not New in Shipbuilding

Concrete vessels have been built in the past. But they have been small barges or the like for inland Water work, with but one or two exceptions. One of these is a three-thousand-ton concrete vessel now under course of con- struction in Moss, Norway. She is ex- pected to be deliv- ered to her owners by the time this arti- .cle appears in print. The first concrete boat really. . dates back to 1849, when M. Lambot, of Carces, ' France, built a small ten- foot rowboat of re-enforced concrete.

While the boat and its: "method of construction were investigated by the French Government, the vessel was evi^ dently far in advance of its time, and its further develop- ment was left in private hands. Almost fifty years later, or in 1899, Carlo Gabellini, of Rome, Italy, built "several < concrete scows and barges, : one of* the latter a one-hundred -fifty-ton vessel for the city of Civita Vecchia. Meantime, small eleven-ton concrete barges had been built in Holland in 1887, and later, a two - hundred -> twenty-ton freight barge in 1909 by German shipbuilders at Frankfort - on - the - Main. In 1910 a similar concrete barge was built for use on the Welland Canal, Canada, while in 191 1\ barges or pontoons made of concrete were successfully built and employed in work at the Panama Canal. In 191 2, Oscar F. Lackey, then harbor engineer of Baltimore, Md., built several five-hundred-ton barges, one of

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