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the 'tween decks under the boat deck. The officers' quarters are on the boat deck, and there is a bridge under a short open-bridge deck above the boat deck. Since this vessel is designed solely for the freight service the number of above-deck erections is far smaller than in the case of the combination freight and passenger steamer illustrated in figures 11 and 12 above, and the tonnage considerations are consequently less complex. The profile shows the location of the orlop deck and of those above, of the engine and boiler rooms, and of the deep tank. The vessel is a twin-screw steamer with oil-burning, reciprocating engines. Fuel oil is ordinarily carried in the large, deep tank placed athwart ships forward of the boilers. The double-bottom and peak tanks are ordinarily used for water ballast except when long-distance steaming requires their use for fuel oil.

The type of ship that will doubtless be largely used for the freight service between the eastern seaboard of the United States and the west coast of South America is illustrated by figures 15 and 16. The vessel illustrated by these two figures has a length of 384 feet on the upper deck, a molded breadth of 50 feet and a molded depth to the upper deck of 28 feet 6 inches. The depth to the bridge deck is 36 feet 6 inches. The midship section shows the vessel to have but three full-length decks. There is an upper and a second deck, but the lower deck is dispensed with, except that the orlop deck subdivides the forward cargo hold. It, however, has two partial decks above the upper deck-a bridge deck and an upper bridge deck. The vessel has a double bottom for fuel and water ballast. The framing is made heavy, in order to compensate for the absence of the lower deck and to reduce the number of hold pillars. The wheel and chart houses and the captain's cabin, moreover, are on a very short deck above the upperbridge deck. The various above-deck erections are similar to those of the vessel illustrated in figures 13 and 14 above, as both vessels are designed for freight service through the Panama Canal. The longitudinal profile of the steamer illustrated in figure 16 shows that oil is carried both in the double bottom and in a deep tank, the deep tank being placed forward of the fireroom. The vessel being an oil-burning steamer has a comparatively small boiler room, differing in this respect from many other oil-burning steamers, which are designed to burn both coal and oil, and which therefore have boiler rooms as large as those on coal-burning steamers of the same power.

The three vessels illustrated by figures 11 to 16 represent standard types of vessels that will probably be largely used in the coastwise and foreign commerce of the United States through the canal. They were designed in 1911 and 1912 for the canal service. Naturally, many kinds of vessels will be operated through the canal. A ship chartered for a single trip or for a limited period may be any available vessel capable of performing the transportation service desired by the charterer. Bulk carriers will be operated both as lines and as single vessels for the transportation of bulk cargoes of coal, ore, nitrate, fuel oil, lumber, grain, and similar products. Doubtless many corporations and individuals shipping bulk cargoes will own, or operate under time charters, such vessels as they require for the marketing of their products.

For the transportation of such bulk cargoes as coal, ore, and grain, when shipments are made regularly and in large volume, special types of vessels such as turret and trunk steamers are used to some extent. For shipping oil in bulk, tank steamers are employed. Figures 17, 18, and 19 illustrate the general design of turret and trunk steamers.

The turret ship is so named because of the turret-like erection extending the entire length of the vessel. The upper, or turret, deck, as is shown in figure 17, is narrower than the harbor or main deck. "The sides of the turret are blended into the harbor deck, and the harbor deck into the vertical side plating by well-rounded corners." (Walton's Present Day Shipbuilding, p. 70.) The hatches, superstructures, and accommodations for officers and crew are on the turret deck. The construction of the hull may follow various designs, and the turret ships may differ materially in details of construction. The midship section given in figure 17 shows a deep hold with two rows of hold pillars, and with a lower deck. By strengthening the framing, the lower deck, or, if preferred, both the lower deck and the hold pillars may be dispensed with. In some vessels all decks below the turret deck are done away with, and the interior of the

FIG. 15. MIDSHIP SECTION OF FREIGHT STEAMER, PANAMA CANAL SERVICE.

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