قراءة كتاب The Pioneer Steamship Savannah: A Study for a Scale Model United States National Museum Bulletin 228, 1961, pages 61-80

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The Pioneer Steamship Savannah: A Study for a Scale Model
United States National Museum Bulletin 228, 1961, pages 61-80

The Pioneer Steamship Savannah: A Study for a Scale Model United States National Museum Bulletin 228, 1961, pages 61-80

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دار النشر: Project Gutenberg
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wheels might be farther aft than is proposed in the reconstruction. However, the smokestack could not then be forward of the wheel shaft as shown by Marestier because it would have had to pass through the engine frame, thus interfering with the movement of the large crosshead. If the engine were abaft the wheel shaft, the stack could have been only as shown by Marestier. The boilers might then have been forward of the wheel shaft only if the stack were at the end away from the firebox. However, the length of the boilers as indicated by the Russian description would then have required them to pass through the bows!

Models have been built of the Savannah in which the engine and boilers are forward of the paddle wheel shaft, and the shaft below the main deck. This was accomplished by placing the engine off center so that the stack came through the decks alongside it. This is an impractical arrangement because it would have created an impossible ballasting problem. The weight of the engine, to port in the models, would have to have been counteracted by ballast to starboard. Due to the coal bunkers, and the possibility of two boilers below the engine in the hold, there would not have been room for sufficient ballast. In addition, were such ballasting possible, the combined weights were too far forward to give proper trim, and a great deal more ballast would have been required far aft, a most impractical proceeding.

The position of the wheel shaft was determined as described earlier. The ship was apparently well-advanced in construction at the time of purchase. Her clamps and shelves supporting her upper deck beams, which then would have been in place, were important strength members. In reconstructing, to place the wheel shaft below these members would not only bring the engine nearly level—it is described and shown inclined by Marestier—but also would immerse the paddle blades too deeply for the draft and depth of the hull. To place the shaft below or through the lowest clamp member would require the shaft centerline to be at least 3 feet below the upper deck, and this would contradict Marestier. These questions indicate the importance of a scaled drawing when deciding arrangement in the reconstruction of a ship under the circumstances existing in the Savannah. Some models have been built with the shaft below deck by disregarding the structural and dimensional objections just outlined.

The question of the number of boilers originally was raised by Braynard. A single boiler with double flues was a common boiler design in American steamboats of 1818–1828, and this form of boiler is shown in a number of Marestier's drawings. In general descriptions, "boiler" and "boilers" are often used interchangeably, and this probably came about through confusion over the number of flues. A "single boiler, double flues," would thus become "boilers," apparently. The Russian description specifically states there were two boilers, and gives specific dimensions; though these probably are not exact. Either a single boiler with double flues, or double boilers, each with a single flue, could have been fitted in the reconstruction. However, fuel space is affected and, with double boilers, the cross-sections of the bunkers are reduced to about 20 square feet each; therefore, the bunkers would have to become much longer. It may be said that the boiler capacities in relation to dimensions of the steam cylinder as indicated in the Russian description far exceed those given by Marestier. As a practical matter of ship design, it seems that the single boiler would have been a more logical fitting than double boilers. The boilers were apparently of copper, and expensive. However, this matter does not affect the hull-form and dimensions established for the reconstruction, as the drawings proved. The Russian description does show that the cargo space was extremely small and practically nonexistent, indicating the effect of the large boiler capacity.

All requirements that have been given can be approximated for space necessary in the hull. It is established that the ship carried about 75 tons of coal and 25 cords of wood. The coal would take up from about 1,700 to 1,850 cubic feet of space, and because of its weight it would have to be bunkered alongside the boilers in the lower hold, where there would be ample room, in the reconstruction, for two bunkers, each in excess of 30 square feet in cross section and about 28 feet in length for a single boiler; one third more bunker space, in length, would be required for double boilers. Such bunkers would together hold about the required tonnage or cubic footage. The cord wood would have required, say, two bunkers each of about 60 square feet in cross section and 20 to 24 feet in length. Because of the light weight, the cord wood could have been stowed in the wings on the lower deck. There is room for the required stowage on the lower deck in the reconstructed hull, leaving ample passages under either side of the engine frame.

Marestier shows the location of the stack as being abreast the buckets on the forward side of the paddle wheels, and it has been so placed in the reconstruction. The deckhouse shown in Marestier's sketch extends from a little forward of the mainmast to a little forward of the paddle wheel axle. Probably this house actually covered the main hatch and the crank-connecting-rod hatchway; therefore, Marestier shows it too short. In the reconstruction, the deckhouse works out as between 17 and 18 feet long. Its width can only be guessed at, but it probably would have been as wide as the opening cut in the upper deck for machinery—say 11 feet. Perhaps this house contained the engineer's stateroom and that of his assistant, as well as a ladderway to the engine room. Doors on the sides of the house gave access to these spaces and to the inboard shaft bearings. Bunker hatches were probably forward of the house and outboard; these are taken as being about 2 feet 6 inches wide and 3 feet 6 inches long—large enough to allow coal baskets to be lowered through them, as well as to allow cord wood to be passed below.

A fidley hatch, in which the stack passed through the upper deck, would have been a square hatch forward of the deckhouse. This hatch, about 21/2 to 3 feet square, would have been fitted with an iron or iron-bound fidley grating, with solid cover over. The stack could have been swivelled, to bring the elbow to leeward. The upper portion of the stack probably overlapped the lower portion at least 3 to 4 feet above the fidley coaming, and the upper stack rested on a collar bearing at the bottom of the overlap. Perhaps straps were bolted to the side of the upper stack to take heaving bars athwartships, by which two men could rotate the upper stack to turn the elbow to leeward.

The bearings of the paddle wheel axle were perhaps four in number. Two, one either side of the crank, may have been secured to the engine frame just inside the deckhouse walls. Two were certainly outboard, one on each side, fastened to the topsides, as shown in Marestier's sketch of the wheel construction. The axle, probably square in cross section, turned only at the bearings and wrist pin. It may have been cast in two parts, each with a crank arm, and then joined by the wrist pin, after the latter had been turned.

The wheels, shown in much detail in Marestier's sketches of the engine, had flanged hubs to which the pivoted arms or spokes were bolted. The fixed arms were integral parts of the outer hubs. The inner flanges were cast with the hubs. To fold the blades, the fixed arms were brought parallel to the rail, then the chain span between each pair of the pivoted blades on top of the wheel was disconnected and a pair of the blades, each way, were dropped on top of the fixed arms, or blades, and lashed there. The wheel was then given a half-revolution and the process repeated. The wheel could then have been unshipped from the hub by sliding it off the square shaft end after removing, let us

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