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Page:Popular Science Monthly Volume 90.djvu/879

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Popular Science Monthly

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���readily prepared and easily assembled straight pieces of stock will replace 2,300 tons of steel

bilge turn itself is formed of a laminated section strongly connected to the previous members. All the parts are adapted to be entirely finished by machiner\^

Another particular construction differing from the method previously followed is the

^Tvw) fuel oil tanks 250 tons capacity / with 7000 miles cruising radius

���use of what corresponds with the top plate of the double-bottom in a steel ship. This timber, of slightly less size than the frame itself, is firmly bolted to the centerline keelson at the middle and then bent downward at each end on a wedge-shaped block between it and the frame member below the turn of the bilge. The frame member is also bent upward slightly so that both pieces of timber are stressed under tension which gives a much greater degree of rigidity. Similarly the side member of the frame is stressed by being bent in slightly at the top and tied to the same frame on the other side by means of the upper deck beam, and a crosswise deck beam or stiffener is used in the hold to add rigidity to the whole frame.

Careful Loading Is Necessary

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. This means that no cargo can be shifted from one side of the vessel to the other after it is once in the hold. While this necessitates careful loading of the ship to give the proper trim, it offers an additional advantage of providing a cargo space clear of beam posts or pillars.

The development of this unusual design of wood ship has been under way for more than three years, and it was a mere coinci- dence that it was practically completed just at the time of our declaration of war against Germany. Mr. Donnelly is a me- chanical engineer who learned his trade as a pattern maker with a famous printing press builder. He became a consulting engineer on wooden drydocks in 1898. It was this experience which evolved his plan of building wooden ships.

��Two types of ships have been devised, as shown in the dia- grams. Two fuel oil tanks will feed four high speed oil engines, giving a cruising radius of seven thousand miles, as shown above, or a triple expansion steam engine with a coal bunker capa- city of five hundred tons will give a cruising radius of five thousand miles as shown at right

��Coal bunKers 500 tons capacity 'with 5,000 mile cruismg radius \

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��Triple expansion steam engine

��four water-tube boilers

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