Page:Popular Science Monthly Volume 90.djvu/878

 862

��Popular Science Monthly

���How the new wooden ship, capable of carrying five thousand five hundred tons of freight, will look when it is finished. In each ship 1,500,000 board feet of southern yellow pine made up into

��hundreds of such vessels to be built simultaneously at various plants throughout the country. This will increase our ton- nage rapidly — which is what must be ac- complished if we are to aid in circumventing the submarine. It is understood that the recently-created Shipping Board of the United States has placed its stamp of approval on the Donnelly design and that it will supervise the construction of a large number of such vessels for use in our trans-Atlantic trade.

Making the Ship Rigid

In construction, the Donnelly boat differs from all previous shipbuilding prac- tice in that it has a heavy wood longitudinal centerline bulkhead which extends clear from the stem to the rudder post. This bulkhead acts much

Two electric generators

��as a girder in a railroad bridge and provides the greater part of the rigidity which has been lacking in previously-constructed wooden boats of the length of 350 feet. The bulkhead is made up of timbers laid one on top of the other, suitably tied together by vertical members.

Another particular departure from pre- vious wooden shipbuilding practice is the manner in which the frames are made from straight mill stock with no hewn or tapered sections. Note the illustration of typical section of old construction, in which frames are shown tapered from keel to rail. As shown in the accompanying illustration of the new construction, the frames or ribs of the vessel are made up of a straight part extending across the bottom from bilge to bilge and a vertical member forming each side from the turn of the bilge to rail. The

���The use of the center longitudinal bulkhead makes it necessary to have side instead of center hatches or openings through which the cargo is deposited in the hold. No cargo can be shifted once it is in the hold

�� �